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Open Hardware Spec
The DIMO Open Hardware Spec is designed to guide manufacturers and device integrators in ensuring that their hardware is compatible with the DIMO platform.
DIMO OPEN HARDWARE SPECIFICATION
REV N/C
December 19 2022
The DIMO Open Hardware Specification is a critical component of the Open Hardware Ecosystem. Prospective manufacturers of DIMO compatible devices are expected to adhere to the below specifications for all aspects of the device’s design. Auditing a device and confirming if the materials, components and design adhere to the below spec is a major aspect approval process for a DIMO compatible device.
Engineers and designers are encouraged to contact DIMO or the DIMO foundation if any questions arise regarding the below specifications.
To be DIMO compatible, devices must meet the following specifications:
- 802.11 b/g/n/ac/ax compatibility: This ensures that the device can connect to modern WiFi networks and communicate with other devices using the latest WiFi standards.
- 2.4 GHz and 5 GHz frequency support: This allows the device to operate on both the 2.4 GHz and 5 GHz frequency bands, which are commonly used by IoT devices.
- WPA2/WPA3 security protocol support: This ensures that the device can securely connect to and communicate over WiFi networks, using the latest security protocols.
- At least 100 Mbps transfer speed: This ensures that the device can transmit and receive data quickly and efficiently over the network.
- Small form factor antenna: This allows the device to be compact and portable, while still maintaining a strong and reliable wireless connection. The antenna can be internal or external.
- Strong signal strength: In addition to having a small form factor antenna, the device should be able to maintain a strong and reliable signal over a reasonable distance. At a distance of 20 feet, the device should have a minimum SNR of 20 dB and a minimum SSI of -70 dBm. This will ensure that the device can effectively communicate with other devices on the network.
Specification Type | Specification |
WiFi | 802.11 b/g/n/ac/ax compatibility |
Frequency | 2.4 GHz, 5 GHz |
Security | WPA2/WPA3 support |
Transfer speed | Minimum 50 Mbps |
Antenna | Small form factor, internal or external |
Signal strength | Minimum SNR of 20 dB and SSI of -70 dBm at a distance of 20 feet |
Tx power | The specific TX power required will depend on the regulatory requirements of the region where the device will be used. In the US, for example, the maximum allowable TX power for 2.4 GHz WiFi devices is 18 dBm. |
DIMO compatible devices with CAN capability must adhere to the following:
- Error detection and correction: A robust CAN bus interface must be able to detect and correct errors in the data transmission, in order to maintain the integrity of the data. For example, the interface may have an error detection rate of at least 95%, and an error correction rate of at least 90%.
- High data rate: A robust CAN bus interface must be able to support high data rates, in order to transfer large amounts of data quickly and efficiently. For example, the interface may have a data rate of at least 1 Mbps. The maximum length of a CAN message is 8 bytes for standard messages and 64 bytes for extended messages.
- Fault tolerance: A robust CAN bus interface must be able to tolerate faults, such as short circuits or open circuits, without affecting the operation of the bus.
- High noise immunity: The CAN bus interface must be able to operate reliably in the presence of electromagnetic interference, in order to maintain the integrity of the data transmission. The Interface may have a noise immunity of at least 30 V/m.
- The physical layer for the CAN devices must use differential signaling with a signaling voltage of 2.5V. The maximum bus length must not exceed 5 meters, and the maximum number of nodes on the bus is 128.
- Compliance with relevant standards: The CAN bus interface must comply with relevant standards, such as ISO 11898 and SAE J1939, which specify requirements for the design and performance of CAN bus interfaces in automotive applications. For example, the interface may be designed to meet the requirements of ISO 11898 and SAE J1939.
- Automotive grade CAN devices for CAN controllers and a CAN transceivers. They must also have additional features, such as support for fault-tolerant systems and fail-safe mechanisms.
Specification Type | Specification |
Error detection and correction | Error detection rate of at least 95%, error correction rate of at least 90% |
Data rate | Data rate of at least 1 Mbps, maximum message length of 8 bytes (standard) or 64 bytes (extended) |
Fault tolerance | Tolerance to faults such as short circuits or open circuits without affecting bus operation |
High noise immunity | Noise immunity of at least 30 V/m |
Physical layer | Differential signaling with 2.5V signaling voltage |
Bus length | Maximum length of 5 meters |
Number of nodes | Maximum of 128 nodes |
Compliance with standards | ISO 11898 and SAE J1939 compliance |
Additional features | Support for fault-tolerant systems and fail-safe mechanisms |
To be DIMO compatible with Bluetooth enabled, devices must meet the following specifications:
- Bluetooth 5.0 or later compatibility: Ensures that the device can connect to and communicate with other Bluetooth devices using the latest Bluetooth standard. Previous Bluetooth standards are not supported.
- Low Energy (BLE) support: Allows the device to use Bluetooth LE for low-power communication with other devices.
- At least 1 Mbps transfer speed: Ensures that the device can transmit and receive data quickly and efficiently over Bluetooth.
- Secure Simple Pairing (SSP) support for below Bluetooth 5.2. : Ensures that the device can securely connect to and communicate with other Bluetooth devices using SSP.
- Small form factor antenna, internal or external: Allows the device to be compact and portable, while still maintaining a strong and reliable Bluetooth connection.
- Low power consumption for battery-powered devices: Ensures that the device can operate efficiently and for an extended period of time on battery power.
- Strong signal strength for reliable communication over a 10-foot range: Ensures that the device can maintain a strong and reliable Bluetooth signal over a distance of 10 feet. Refer to SIG standards https://www.bluetooth.com/specifications/specs/
- TX power of 18 dBm or lower for compliance with regulatory requirements: Ensures that the device complies with regulatory requirements for Bluetooth transmission power. Refer to SIG standards https://www.bluetooth.com/specifications/specs/
- Support for Bluetooth profiles such as HFP, HSP, A2DP, and AVRCP: Ensures that the device can connect to and communicate with a range of devices and applications using common Bluetooth profiles. Refer to SIG standards https://www.bluetooth.com/specifications/specs/
Specification Type | Specification |
Bluetooth | 5.2 or later compatibility |
Energy | Low Energy (LE) support |
Data rate | Enhanced Data Rate (EDR) support |
Transfer speed | At least 1 Mbps |
Security | Secure Simple Pairing (SSP) support |
Antenna | Small form factor, internal or external |
Power consumption | Low power for battery-powered devices |
Signal strength | Minimum SNR of 20 dB and SSI of -70 dBm at a distance of 10 feet |
TX power | 18 dBm or lower |
Bluetooth profiles | HFP, HSP, A2DP, and AVRCP support |
NFC designed in a DIMO compatible device must comply with the following: \
- The NFC device operates at the 13.56 MHz frequency and is compatible with the ISO/IEC 14443 and ISO/IEC 15693 standards, which are commonly used in NFC systems. \
- The NFC device supports the NFC Forum Type 2 and Type 4 tags, which are standardized NFC tag types used for a variety of applications. \
- The NFC device has a transfer speed of at least 212 kbps, which is the minimum speed required for fast and efficient data transfer over NFC. \
- The NFC device supports the FeliCa and MIFARE protocols, which are widely used in NFC systems for various applications such as access control and payment. \
- The NFC device has a small form factor internal NFC antenna, which allows it to be easily integrated into a variety of devices with limited space. \
- The NFC device has low power consumption, making it suitable for use in battery-powered devices. \
- The NFC device has strong signal strength**, ensuring reliable communication over a reasonable distance. \
- The NFC device supports NFC-based security protocols such as WPA2-Enterprise and FIDO U2F, which provide additional security measures to protect against unauthorized access.
** The signal strength values for SNR (Signal-to-Noise Ratio) and SSI (Signal Strength Indicator) in NFC are measured in decibels (dB). The specific values can vary depending on the specific NFC standard, the type of NFC tags being used, and the distance between the NFC reader and the NFC tags.
For NFC devices operating at the 13.56 MHz frequency and compliant with the ISO/IEC 14443 and ISO/IEC 15693 standards, the following signal strength values may be used as a general reference:
SNR: -20 dB to -30 dB
SSI: -70 dBm to -80 dBm
Keep in mind that these are just general reference values and the actual signal strength values may vary depending on the specific NFC system and configuration. It is also important to note that the signal strength values for SNR and SSI are not directly comparable, as they measure different aspects of the NFC signal.
SNR measures the ratio of the NFC signal to the noise level in the system, while SSI measures the power of the NFC signal. A higher SNR value indicates a stronger signal with less noise, while a higher SSI value indicates a stronger signal. In general, higher SNR and SSI values are desirable for reliable NFC communication.
Specification Type | Specification |
Operating frequency | 13.56 MHz |
Compatible standards | ISO/IEC 14443, ISO/IEC 15693 |
Supported tag types | NFC Forum Type 2, Type 4 |
Data transfer rate | 212 kbps or higher |
Supported protocols | FeliCa, MIFARE |
Antenna | Small form factor internal NFC antenna |
Power consumption | Low power consumption |
Signal strength | Strong signal strength (SNR: -20 dB to -30 dB, SSI: -70 dBm to -80 dBm) |
Security protocols | WPA2-Enterprise, FIDO U2F |
DIMO Compatible IoT Hardware Device specification using USB:
- All USB connectors must be USB-C type and protected against ESD (electrostatic discharge).
- Durability: The device must be able to withstand rough handling and extreme environmental conditions (such as temperature, humidity, and vibration).
- Charging capacity: The device must be able to charge efficiently and quickly, with a maximum charging speed of 3.0A. Any additional USB charging specifications are not a requirement.
- Data speeds: The device must support data transfer speeds of at least USB 2.0 standard (480Mbps).
- Compatibility: The device must be compatible with a wide range of operating systems, including but not limited to Windows, MacOS, Linux, and Android.
- Security: The device must implement secure data transfer and storage, including encryption and authentication measures.
- Ease of use: The device must be user-friendly, with a clear and intuitive interface.
- Voltage: The voltage of any USB ports must be 5.0V +/- 5% according to USB specifications.
- Certifications: The device must meet all relevant industry certifications and standards, including FCC and CE.
- USB cables: All included USB cables must be shielded, of high quality, and be USB 3.2 compatible (even if only for charging, the cable must be capable of data transmission to a USB 3.2 standard).
This specification outlines the requirements for DIMO compatible LoRaWAN devices that operate on the Helium network and other networks.
- DIMO compatible LoRaWAN devices should support the following frequencies based on the region they are deployed in:North America: 902-928 MHzEurope: 862-870 MHzChina: 470-510 MHzAustralia: 915-928 MHzData Transfer Rate:DIMO compatible LoRaWAN devices should support a minimum data transfer rate of 27 kbps. Higher rates may be supported depending on the specific device and the network it is connected to.
- DIMO compatible LoRaWAN devices should support the LoRaWAN protocol, as well as any additional requirements by the intended network.
- Antenna requirements for DIMO compatible LoRaWAN devices may vary depending on the specific device and its intended use, but generally an internal antenna is preferred for compact devices and an external antenna is preferred for devices with larger coverage requirements.
- Power consumption for DIMO compatible LoRaWAN devices should be as low as possible, with a recommended maximum of around 1.5 mW in sleep mode and 20 mW in active mode.
- Compatible LoRaWAN devices should have a minimum signal-to-noise ratio (SNR) of around -6 dB and a minimum signal strength indicator (SSI) of around -105 dBm in order to ensure reliable communication.
Specification Type | Specification |
Frequency | North America: 902-928 MHz, Europe: 862-870 MHz, China: 470-510 MHz, Australia: 915-928 MHz |
Data Transfer Rate | Minimum of 0.3 kbps |
Protocols | LoRaWAN, additional protocols may be required by the network |
Antenna Requirements | Internal antenna preferred for compact devices, external antenna preferred for larger coverage requirements |
Power Consumption | Maximum of 1.5 mW in sleep mode, 100 mW in active mode |
Signal Strength | Minimum SNR of -6 dB, minimum SSI of -105 dBm |
All DIMO compatible OBDII devices must comply with the ISO 15765 standard for communication over the Controller Area Network (CAN) bus.
This includes complying with the following standards:
J1962 – Defines the physical connector used for the OBD-II interface.
J1850 – Defines a serial data protocol.
J1978 – Defines minimal operating standards for OBD-II scan tools
J1979 – Defines standards for diagnostic test modes
J2012 – Defines standards trouble codes and definitions.
J2178-1 – Network message header formats and physical address assignments
J2178-2 – Gives data parameter definitions
J2178-3 – Defines standards for network message frame IDs for single byte headers
J2178-4 – Defines standards for network messages with three byte headers*
J2284-3 – Defines 500K CAN physical and data link layer
J2411 – Describes the GMLAN (Single-Wire CAN) protocol, used in newer GM vehicles.
In addition to ISO 15765, it is strongly encouraged that DIMO compatible devices also support the following protocols:
- ISO 14230-4 (KWP2000): The Keyword Protocol 2000 is commonly used in 2003+ cars in Asia and other regions.
- ISO 9141-2: This protocol is used in EU, Chrysler, and Asian cars from 2000-2004.
- SAE J1850 (VPW): This protocol is primarily used in older GM vehicles.
- SAE J1850 (PWM): This protocol is primarily used in older Ford vehicles.
**Connector Pinout
**Here is a list of the OBD2 pinout and a brief description of each pin:
1 - Manufacturer discretion
2 - Bus positive line of SAE J1850 PWM and VPW
3 - Manufacturer discretion
4 - Chassis ground
5 - Signal ground
6 - CAN high (ISO 15765-4 and SAE J2284)
7 - K-line of ISO 9141-2 and ISO 14230-4
8 - Manufacturer discretion
9 - Manufacturer discretion
10 - Bus negative line of SAE J1850 PWM only (not SAE 1850 VPW)
11 - Manufacturer discretion
12 - Not connected
13 - Manufacturer discretion
14 - CAN low (ISO 15765-4 and SAE J2284)
15 - L-line of ISO 9141-2 and ISO 14230-4
16 - Battery power (supplied when ignition is off)
It's important to note that not all OBD2 connectors will have all of these pins, as the pinout can vary depending on the specific communication protocol being used. Additionally, some manufacturers may have their own proprietary protocols that use different pins.
For DIMO compatible devices, LTE/5G communication must comply with all relevant regional laws and certification standards. This includes, but is not limited to, standards such as 3GPP Release 8, 9, 10, 11, 12, 13, 14, 15, 16, and any additional standards required by the specific region in which the device will be used.
In addition to complying with regional laws and certification standards, DIMO compatible devices should also support multi-carrier IoT network providers and SIMs. This allows for greater flexibility and increased reliability, as a vehicle may need to connect to multiple carriers and networks if necessary on a single trip.
Support for multi-carrier IoT network providers and SIMs also allows for easier deployment and management of the device, as it can be used with multiple carriers and networks without the need for additional hardware or software modifications. This can save time and cost in the deployment and management of the device, and can increase its overall reliability and uptime.
Overall, the support for multi-carrier IoT network providers and SIMs is an important specification for DIMO compatible devices, as it ensures that the device can be used effectively in a variety of different regions and environments.
The LTE/5G internal antenna requirements for the US and Europe may include the following:
- Frequency range: The antenna should be designed to operate over the relevant frequency bands for LTE/5G in the region that the device will be deployed.
- Gain and efficiency: The antenna should provide a sufficient gain and efficiency to ensure reliable communication and support the required data rates for LTE/5G. This may vary depending on the specific frequency bands and operating conditions. \
- Size and form factor: The antenna should be compact and have a suitable form factor for integration into the device. This may require careful consideration of the antenna geometry, materials, and placement within the device if the antenna is custom for the device.
- Compatibility with other wireless technologies: The antenna should be compatible with other wireless technologies, such as WiFi and Bluetooth, to avoid interference and ensure coexistence with other wireless devices.
- Compliance with regulatory standards: The antenna should meet the relevant regulatory standards, such as FCC Part 15 and ETSI EN 301 489, to ensure compliance with the legal requirements for wireless devices in the US and Europe.
Overall, the LTE/5G internal antenna requirements should balance performance, size, compatibility, and compliance to support reliable and efficient communication in these regions. For other regions, please consult the DIMO Foundation
GNSS \
The DIMO GPS receiver specification is intended to guide manufacturers in designing IoT devices with GPS capabilities. It is important for manufacturers to ensure that their devices comply with regional requirements in order to ensure that they can be used in different parts of the world.
For the US, the following requirements must be met:
- A GPS receiver must be able to receive signals from at least four GPS satellites simultaneously. This is necessary in order to provide accurate positioning information.
- The receiver must be able to receive signals from the L1 and L2 frequency bands. These are the frequencies used by GPS satellites, and a receiver must be able to receive signals from both in order to provide accurate positioning information.
- The receiver must be able to receive signals at a minimum strength of -130 dBm. This is necessary in order to ensure that the receiver can function properly in a variety of environments.
- Relevant standards for GPS devices in the US include ISO 17123-1, ANSI C63.4, and FCC Part 15. Manufacturers must ensure that their devices comply with these standards in order to be used in the US.
If a manufacturer is designing a device for a region outside of the US, it is recommended that they consult the DIMO foundation for further guidance on regional requirements.
This is a specification for DIMO compatible hardware devices that utilize displays that are capable of outdoor use and are specifically designed for automotive purposes. Only OLED and paperwhite display types are permitted on DIMO compatible devices.
- Resolution: 1080p (Full HD) or higher
- Aspect ratio: 16:9 or higher
- Refresh rate: 60 Hz or higher
- Brightness: 500 nits or higher
- Contrast ratio: 1000:1 or higher
- Durability: resistant to sunlight, extreme temperatures, and moisture
- Touch: capacitive touch only
- Drop testing: meets or exceeds automotive industry standards (e.g. SAE J1211)
- Automotive specifications: meets or exceeds relevant automotive industry standards (e.g. SAE J1455, SAE J1292)
- Resolution: 300 dpi or higher
- Aspect ratio: 4:3 or higher
- Refresh rate: N/A (static display)
- Brightness: 300 nits or higher
- Contrast ratio: N/A (static display)
- Durability: resistant to sunlight, extreme temperatures, and moisture
- Touch: capacitive touch only
- Drop testing: meets or exceeds automotive industry standards (e.g. SAE J1211)
- Automotive specifications: meets or exceeds relevant automotive industry standards (e.g. SAE J1455, SAE J1292)
Note: The above specifications are general guidelines and may vary depending on the specific application and use case. It is important to carefully consider the needs and requirements of the device and the environment in which it will be used when selecting the appropriate display.
In-cabin Cameras for DIMO Compatible Devices \
DIMO compatible devices that utilize cameras for in-cabin use for dashcam, driver monitoring, rearview, or sentry mode must comply with the following requirements:
- Resolution: The camera should have a minimum resolution of 1080p (1920 x 1080 pixels) in order to capture clear and detailed images.
- Optical zoom: The camera should have a minimum optical zoom of 2x in order to allow for some flexibility in adjusting the focus and framing of the image.
- Autofocus: The camera should have a fast and reliable autofocus system in order to quickly and accurately adjust the focus of the image.
- Temperature: The camera should be able to operate within a temperature range of -40°C to 80°C (-40°F to 176°F) in order to function properly in a range of environmental conditions.
- Frame rate: The camera should have a minimum frame rate of 30 frames per second (fps) in order to capture smooth and fluid motion.
- Field of view: The camera should have a minimum field of view of 120 degrees in order to capture a wide area within the passenger compartment.
- Lens distortion: The camera should have minimal lens distortion in order to produce accurate and undistorted images.
- Image sensor: The camera should use a CMOS image sensor with a minimum pixel size of 2.8 micrometers in order to capture high-quality images.
- Infrared/night vision: The camera should have the capability to capture images in low light conditions and at night using infrared illumination.
- Shutter speed: The camera should have a minimum shutter speed of 1/30th of a second in order to freeze motion and reduce blur in images.
- Shutter type: The camera should use a rolling shutter in order to minimize motion blur and reduce power consumption.
In terms of automotive specifications, the camera should be able to withstand the vibrations and stresses of driving, and should be resistant to water, dust, and other environmental factors. It should also be able to operate at a wide range of voltages and have a low power consumption in order to be suitable for use in a vehicle. Some specific automotive specifications that may apply to in-cabin camera use include:
- SAE J1211, which covers the performance and testing of driver monitoring systems
- ISO 26262, which covers functional safety for road vehicles.
Overall, the camera should be able to capture high-quality images and video, with minimal distortion and noise, and be able to operate in a range of environmental conditions. It should also have a fast and reliable autofocus system, and be resistant to the stresses of driving and environmental factors, in order to be suitable for use in IoT devices in an automotive setting.
DIMO requires automotive grade microcontrollers for DIMO approved devices, and have the following technical requirements:
- AEC-Q100 qualification: The microcontroller should be qualified according to the Automotive Electronics Council (AEC) Q100 standard, which defines the quality and reliability requirements for automotive electronics. This standard covers a wide range of automotive applications, including engine control, powertrain control, and safety-critical systems.
- Temperature range: The microcontroller should be able to operate over a wide temperature range, typically from -40°C to +125°C, to ensure reliable performance in extreme environments.
- High-speed communication interfaces: The microcontroller should support high-speed communication interfaces, to enable efficient data transfer within the vehicle.
- Hardware security features: The microcontroller should include hardware security features, such as secure boot, to protect against unauthorized access and tampering.
- Robust packaging: The microcontroller should be packaged in a robust and durable package, such as a quad flat no-leads (QFN) or ball grid array (BGA), to withstand the mechanical and thermal stresses of the automotive environment.
Overall, automotive grade microcontrollers should meet the relevant industrial specifications and standards, such as AEC-Q100 and ISO 26262, to ensure reliability, safety, and performance in automotive applications.
Manufacturer requirements for processors and micro-controllers used in DIMO compatible devices:
- All processors and micro-controllers used in DIMO compatible devices must be authentic and from a reputable manufacturer. Proof of authenticity, such as a certificate or invoice, must be provided.
- The following manufacturers are approved for use in DIMO compatible devices:
- Intel
- AMD
- ARM
- Microchip
- Atmel
- NXP
- Texas Instruments
- Renesas
- Nordic Semiconductors
- NVIDIA
- STM
- Infineon
- Onsemi
- Any processors or micro-controllers used must be automotive grade.
- Any processors or micro-controllers used must not be manufactured in China.
- All microcontrollers and processors used will be examined using a cat scan or electron microscope to ensure authenticity.
- In order for a DIMO compatible device to be approved, sufficient quantity of parts must be available from the manufacturer.
- Any processors or micro-controllers that do not meet these specifications will not be approved for use in DIMO compatible devices.
- Compact size: The speakers should be small enough to fit in the allotted space within the vehicle without causing any interference with other components.
- Noise level: The noise level of the speakers should be low enough to be inaudible to the occupants of the vehicle, with a noise level for buzzers even lower.
- Frequency range: The speakers should be able to reproduce frequencies from 20 Hz to 20,000 Hz (20 kHz) to provide a full and balanced sound.
- Sensitivity: The microphone should have a sensitivity of at least -45 dBV/Pa.
- Size: The microphone should be small enough to fit in the allotted space within the vehicle without causing any interference with other components.
- Frequency range: The microphone should be able to accurately pick up frequencies from 50 Hz to 16,000 Hz (16 kHz) in order to capture the full range of speech and other sounds.
- Noise (electronic): The microphone should have an electronic noise level of less than 60 dBV.
- Sound pressure level wake-up (SPL): The microphone should be able to detect a sound
- pressure level of at least 70 dB SPL in order to activate voice recognition or other features.
- I2S: The microphone should support the Inter-IC Sound (I2S) protocol for digital audio transmission.
- Durable: The headphone jack should be able to withstand at least 10,000 insertion and removal cycles.
- ESD protected: The headphone jack should be able to withstand an electrostatic discharge of at least 5 kV.
- Secure contact: The contact points within the headphone jack should have a retention force of at least 50 N.
- Connector type: The 3.5mm headphone jack should be the only accepted method for wired audio connection to ensure compatibility with a wide range of devices.
In terms of automotive standards, the audio devices should comply with:
- ISO 10487, which specifies the general requirements for connectors for in-vehicle audio systems.
- ISO 7736, which specifies the general requirements for in-vehicle audio head units.
- SAE J553, which specifies the general requirements for in-vehicle audio amplifiers
- SAE J1850, which specifies the requirements for in-vehicle audio data buses.
DIMO compatible devices with accelerometers must adhere to the following specifications:
- Measurement Range: This refers to the range of acceleration that the accelerometer is able to measure, typically specified in g's (units of gravitational acceleration). The measurement range of the accelerometer must be at least +/- 16g.
- Operating Temperature: This refers to the temperature range over which the accelerometer can operate correctly. It is typically specified in degrees Celsius. The operating temperature range of the accelerometer must be at least -40 to +125°C.
- Accelerometer Sensitivity: This refers to the output of the accelerometer per unit of acceleration. It is typically specified in mV/g or pC/g. A higher sensitivity value means that the accelerometer will produce a larger output signal for a given acceleration. The nonlinearity of the accelerometer must be no more than 1% of the full-scale range.
- Nonlinearity: This refers to the deviation of the accelerometer's output from a linear relationship with acceleration. It is typically specified as a percentage of the full-scale range. A lower nonlinearity value indicates better performance.
- Package Alignment Error: This refers to the error introduced by misalignment between the accelerometer package and the sensitive axis. It is typically specified in degrees and should be as low as possible. The package alignment error of the accelerometer must be no more than 0.5°.
- Orthogonal Alignment Error: This refers to the error introduced by misalignment between the sensitive axis of the accelerometer and the direction of acceleration. It is typically specified in degrees and should be as low as possible. The alignment error of the accelerometer must be no more than 0.5°.
- Cross-Axis Sensitivity: This refers to the sensitivity of the accelerometer to acceleration in a direction other than the sensitive axis. It is typically specified as a percentage of the sensitivity in the sensitive axis direction. A lower cross-axis sensitivity value indicates better performance. The cross-axis sensitivity of the accelerometer must be no more than 5% of the sensitivity in the sensitive axis direction.
- Zero-g Bias Level: This refers to the output of the accelerometer when it is not subjected to any acceleration. It is typically specified in mV or pC and should be as low as possible. The zero-g bias level of the accelerometer must be no more than 50 µV.
- Accelerometer Noise Density: This refers to the root mean square (RMS) value of the noise present in the accelerometer output, typically specified in µg/√Hz. A lower noise density value indicates better performance. The accelerometer noise density must be no more than 50 µg/√Hz.
- Total Noise: This refers to the RMS value of the total noise present in the accelerometer output, including both noise density and random noise. It is typically specified in µg and should be as low as possible. The total noise of the accelerometer must be no more than 250 µg.
- Compliance with relevant standards: An automotive-grade IMU must comply with relevant standards, such as ISO 26262 and SAE J3061, which specify requirements for the safety and performance of automotive electronics. For example, the IMU may be designed to meet the functional safety requirements of ISO 26262, with a failure rate of less than 1 FIT (failures in time).
Specification Type | Specification |
Measurement Range | +/- 16g |
Operating Temperature | -40 to +125°C |
Accelerometer Sensitivity | 1% of the full-scale range |
Nonlinearity | < 1% of the full-scale range |
Package Alignment Error | < 0.5° |
Orthogonal Alignment Error | < 0.5° |
Cross-Axis Sensitivity | < 5% of the sensitivity in the sensitive axis direction |
Zero-g Bias Level | < 50 µV |
Accelerometer Noise Density | < 50 µg/√Hz |
Total Noise | < 250 µg |
Compliance with Relevant Standards | ISO 26262, SAE J3061, with a failure rate of less than 1 FIT |
If in a region outside of the US, please consult the DIMO foundation.
Here is a possible specification for a small electronic gyroscope integrated circuit for use in DIMO compatible IoT devices with the appropriate values for an automotive grade gyroscope:
- Angular / Rotary Axes: 3-axis (X, Y, Z) - This specification refers to the number of rotational axes that the gyroscope can measure. In this case, the gyroscope is a 3-axis gyroscope, meaning it can measure rotational motion in 3 dimensions: the X axis, the Y axis, and the Z axis.
- Angular Rate Range: ±1000°/s - This specification refers to the range of angular rates that the gyroscope can measure. The angular rate is a measure of the speed at which an object is rotating around an axis, expressed in degrees per second (°/s). In this case, the gyroscope has an angular rate range of ±1000°/s, meaning it can measure angular rates from -1000°/s to +1000°/s.
- Linearity: ±1% - This specification refers to the accuracy with which the gyroscope can measure angular rate. Linearity is a measure of how closely the output of the gyroscope matches the input over a range of angular rates. In this case, the gyroscope has a linearity of ±1%, meaning that its output should be within 1% of the actual input over a range of angular rates.
- Angular Transverse Sensitivity: <0.01% - This specification refers to the sensitivity of the gyroscope to angular motion in a direction perpendicular to the axis of rotation. Angular transverse sensitivity is a measure of how much the output of the gyroscope is affected by angular motion in a direction other than the axis of rotation. In this case, the gyroscope has an angular transverse sensitivity of less than 0.01%, meaning that it is highly resistant to angular motion in directions other than the axis of rotation.
- Bias Stability: <0.005°/s - This specification refers to the stability of the gyroscope's zero-rate output, or "bias." The bias is the output of the gyroscope when it is not experiencing any angular motion. Bias stability is a measure of how stable the bias is over time. In this case, the gyroscope has a bias stability of less than 0.005°/s, meaning that the bias should remain stable and within a small range of values over time.
- Random Walk: <0.005°/s/√hr - This specification refers to the accuracy of the gyroscope over long periods of time. Random walk is a measure of how much the output of the gyroscope drifts over time due to random errors. In this case, the gyroscope has a random walk of less than 0.005°/s/√hr, meaning that the output should remain accurate over long periods of time despite the presence of random errors
- Operating temperature range: The gyroscope should be able to operate within a temperature range that is suitable for the automotive environment, such as -40°C to +125°C.
- shock and vibration resistance: The gyroscope should be able to withstand the shock and vibration typically encountered in an automotive environment..
- Rate-integrating Gyro: Yes - This specification refers to the type of gyroscope being used. A rate-integrating gyro is a type of gyroscope that integrates the angular rate over time to provide a measure of the angular displacement, or change in angle, of an object. In this case, the gyroscope is a rate-integrating gyro, meaning it can measure both angular rate and angular
Specification Type | Specification |
Anular/Rotary Axes | 3-axis (X, Y, Z) |
Angular Rate Range | ±1000°/s |
Linearity | ±1% |
Angular Transverse Sensitivity | <0.01% |
Bias Stability | <0.005°/s |
Random Walk | <0.005°/s/√hr |
Operating Temperature Range | -40°C to +125°C |
Shock and Vibration Resistance | N/A |
Rate-Integrating Gyro | Yes |
All gyroscopes used (either separate or integrated in an IMU) must be automotive grade.
Magnetometer integrated circuits for use in DIMO compatible devices must adhere to the following.
Operating Temperature: The magnetometer has an operating temperature range of -40°C to +125°C, which is suitable for the automotive environment.
Full-scale range: This specification refers to the range of magnetic fields that the magnetometer can measure. The full-scale range is the maximum magnetic field that the magnetometer can detect, and is typically expressed in units of Gauss. DIMO compatible devices must have a full scale range of 2 Gauss
Sensitivity: Refers to the sensitivity of the magnetometer to magnetic fields. Sensitivity is a measure of how small of a magnetic field the magnetometer can detect, and is typically expressed in units of microtesla per digit. The magnetometer must have a sensitivity of 0.1 microtesla per digit.
Noise: This specification refers to the noise level of the magnetometer. Noise is a measure of the random errors in the output of the magnetometer, and is typically expressed in units of microtesla. The magnetometer must have a 0.01 microtesla.
Output Data Rate: This specification refers to the rate at which the magnetometer produces output data. The output data rate is a measure of how frequently the magnetometer produces new readings, and is typically expressed in units of samples per second. In this case, the magnetometer has an output data rate of 100 samples per second
Magnetic field range: Refers to the range of magnetic fields that the magnetometer can measure. The magnetic field range is the range of values over which the magnetometer can provide accurate readings, and is typically expressed in units of Gauss. In this case, the magnetometer can measure magnetic fields within a range of ±2 Gauss.
Compass heading accuracy: This specification refers to the accuracy of the magnetometer when used as a compass. Compass heading accuracy is a measure of how accurately the magnetometer can determine the direction of the earth's magnetic field, and is typically expressed in units of degrees. In this case, the magnetometer has a compass heading accuracy of 1 degree.
Hard Iron/Soft Iron sensitivity: This specification refers to the magnetometer's sensitivity to hard iron and soft iron interference. Hard iron interference is caused by permanent magnets or ferromagnetic materials, while soft iron interference is caused by materials that become magnetized in the presence of a magnetic field. The hard iron/soft iron sensitivity is a measure of how much these sources of interference affect the output of the magnetometer, and is typically expressed in units of Gauss. In this case, the magnetometer has a hard iron/soft iron sensitivity of 0.5 Gauss
Specification Type | Specification |
Operating Temperature | -40°C to +125°C |
Full-scale range | 2 Gauss |
Sensitivity | 0.1 microtesla per digit |
Noise | 0.01 microtesla |
Output Data Rate | 100 samples per second |
Magnetic field range | ±2 Gauss |
Compass heading accuracy | 1 degree |
Hard Iron/Soft Iron sensitivity | 0.5 Ga |
Robust power supply requirements may include the following:
- Wide range of input voltage: The power supply should be able to accept a wide range of Vehicle DC voltages.
- High efficiency: The power supply should be designed for high efficiency to reduce power loss and minimize heat generation. This can be achieved through the use of high-quality components and advanced power management techniques.
- Overvoltage and overcurrent protection: The power supply should be equipped with protective measures to prevent damage from overvoltage and overcurrent events. This can include features such as overvoltage protection, overcurrent protection, and short circuit protection.
- EMC compliance: The power supply should meet the relevant electromagnetic compatibility (EMC) standards to ensure that it does not generate excessive electromagnetic interference that can affect other electronic devices.
- Durability and reliability: The power supply should be designed to withstand the rigors of everyday use and be reliable over time. This can include features such as high-quality components, robust construction, and extensive testing.
- Overall, consumer electronics power supply requirements should balance performance, safety, and compliance to provide a robust and reliable power source for the device.
For a device that draws 12V power from an OBDII port should include the following:
- The input voltage range: The OBDII port is typically designed to provide power at a voltage of 12V, with a tolerance range of +/- 8%. Therefore, the input voltage range for the device should be at minimum 12.96V.
- The input current requirement: The maximum current that can be drawn from an OBDII port is typically limited to 6A. Therefore, the device should be designed to draw no more than 5A of current from the OBDII port.
- The output voltage: The device should be designed to provide a regulated output voltage of <11V to power its internal components.
- The output current capability: The device should have sufficient output current capability to power all of its internal components. The exact amount of current required will depend on the specific components used in the device.
- Protection features: The power supply should include protection features such as overvoltage, overcurrent, and short-circuit protection to prevent damage to the device and the OBDII port in case of fault conditions.
- Ability to switch off the power supply at its source during vehicle shutdown.
- EMI/EMC compliance: The power supply should be designed to comply with relevant EMI/EMC standards to ensure that it does not interfere with the operation of the vehicle's electronic systems.
DIMO compatible devices with batteries must have sufficient capacity to ensure prolonged and reliable operation:
- The battery must be able to power the device in sleep mode for a period of greater than 1 year.
- The battery must be able to maintain at least 95% of its capacity after 500 full charge and discharge cycles.
- The battery must be able to operate within a temperature range of -40 to 85 degrees Celsius.
- The battery must meet all relevant safety and performance standards, including but not limited to UL 1642, IEC 62133, and UN 38.3. \
- The battery must be compatible with the device's charging system and meet all relevant electrical and mechanical requirements.
Please note that actual requirements for the battery capacity may vary depending on the specific needs of the device and application. It is important to carefully consider the battery's performance and safety requirements in order to ensure reliable and safe operation of the DIMO device.
Type
Here is a sample specification for battery types for DIMo compatible IoT devices:
- The chemistry and configuration of the battery is not as important as long as the charging circuitry accommodates the chemistry and configuration.
- All batteries must be replaceable with easy to use connectors.
- The part number for the battery must be visible somewhere on the battery or the product.
- The battery must be able to operate within a temperature range of -40 to 85 degrees Celsius.
- Any RTC (real-time clock) backup batteries must be automotive grade and allow for an RTC to be powered for a minimum of 5 years.
- The battery must meet all relevant safety and performance standards, including but not limited to UL 1642, IEC 62133, and UN 38.3.
- The battery must be compatible with the device's charging system and meet all relevant electrical and mechanical requirements.
- Any lithium-based batteries must adhere to all relevant regulations for shipping, including but not limited to the regulations of the state in which they will be shipped.
DIMO compatible devices must comply with the following:
- High discharge rate if required: Backup batteries in electronic devices must be able to discharge a large amount of current quickly if the application requires it, in order to support the high power demands of the device.
- High capacity and long life: Backup batteries in DIMO devices must be able to sustain the device in sleep mode for a period of 1 year.
- Low self-discharge: Backup batteries in electronic devices must have a low self-discharge rate, in order to maintain their charge over time. For example, the battery may have a self-discharge rate of less than 5% per year.
- High temperature tolerance: Backup batteries in electronic devices must be able to withstand high temperatures, in order to operate reliably in the harsh environment of a vehicle. DIMO devices with backup batteries must be able to operate at temperatures ranging from -40 to 85 degrees Celsius.
Note: It is important to ensure that the chosen material is capable of withstanding the operating environment of the IoT device and has the necessary properties for anti-ESD (Electrostatic Discharge) applications. It may also be helpful to consider the inclusion of additional features such as UV resistance, chemical resistance, and impact resistance, depending on the specific requirements of the device.
The device’s dimensions should not be excessive, but include enough space for any electronics and cooling.
Not to exceed 500g if plugged directly into an OBDII port. If a device is greater than 1KG, mounting brackets must be provided.
DIMO compatible devices must be injection molded where possible. Acceptable materials for injection molding include:
ABS (Acrylonitrile Butadiene Styrene)
PC (Polycarbonate)
PA (Polyamide/Nylon)
For devices that are CNC machined, the above plastics are still preferred. Aluminum 7075-T6 is to be used for any enclosures that require metal. \
Any color!
The temperature spec of a device refers to the range of temperatures at which it can operate safely and effectively. The International Organization for Standardization (ISO) has established the standard ISO 16750-4 for electronic temperature ratings, which defines the methods for determining and indicating the temperature range at which an electronic device can operate.
DIMO compatible must adhere to this standard, ensuring that they can operate within a specified temperature range without experiencing degradation or failure.
Mounting location | Engine compartment |
To body | I, K |
To frame | G |
On the flexible plenum chamber, not rigidly attached | I, K |
In the flexible plenum chamber, not rigidly attached | I, K |
On the engine | K, M |
In the engine | K, M |
On the transmission/retarder | M |
In the transmission/retarder | M |
Passenger compartment | |
without special requirements | D |
exposed to direct solar radiation | G |
exposed to radiated heat | H |
Code | Minimum operating temperature (°C) | Maximum operating temperature (°C) |
|---|---|---|
A | -20 | 65 |
B | -30 | 65 |
C | -40 | 65 |
D | -40 | 70 |
E | -40 | 75 |
F | -40 | 80 |
G | -40 | 85 |
H | -40 | 90 |
I | -40 | 95 |
J | -40 | 100 |
K | -40 | 105 |
L | -40 | 110 |
M | -40 | 115 |
N | -40 | 120 |
O | -40 | 125 |
P | -40 | 130 |
Q | -40 | 140 |
R | -40 | 150 |
S | -40 | 155 |
T | -40 | 160 |
Z | -40 | as agreed upon |
DIMO compatible devices must adhere to and demonstrate compliance to one of the below Automotive vibrations classifications:
- GM3172: This standard specifies requirements for vibration testing of automotive products, including the test frequency range, test duration, and acceptance criteria.
- JIS D 1601: This standard specifies requirements for vibration testing of electrical and electronic products, including the test frequency range, test duration, and acceptance criteria.
- SAE J1211: This standard specifies requirements for vibration testing of electrical and electronic products, including the test frequency range, test duration, and acceptance criteria.
- ISO 10326-1:2016: This standard provides guidance for vibration testing of electrical and electronic products, including the test frequency range, test duration, and acceptance criteria. It also provides guidance on the design and execution of vibration tests, as well as the interpretation of test results.
All DIMO compatible devices must adhere to IP65 standards for dust and water intrusion.
https://en.wikipedia.org/wiki/IP_code
IP65 is a standard that specifies the requirements for an electrical enclosure to provide protection against the intrusion of dust and water. A device that meets this standard must be designed and constructed in such a way that it is completely protected against the intrusion of dust, and can withstand low-pressure jets of water from any direction without any harmful effects. To meet this standard, the device must be designed and constructed with the following requirements in mind:
- The enclosure must be designed to prevent the ingress of dust, and any openings or gaps must be sealed to prevent the entry of dust.
- The enclosure must be able to withstand low-pressure jets of water from any direction without any harmful effects. This may require the use of special seals and gaskets, as well as water-resistant materials and coatings.
- The enclosure must be sturdy and durable, and able to withstand the mechanical stresses and vibrations that may be encountered during normal use.
- The enclosure must be easy to clean and maintain, and any removable parts or panels must be designed to be securely attached and easy to remove and replace.
- The enclosure must be designed and constructed to meet any other relevant safety and performance standards, such as those related to electrical safety, electromagnetic compatibility, and environmental conditions.
ESD COMPATIBILITY
Electrostatic discharge (ESD) immunity refers to a device's ability to operate properly when exposed to electrostatic discharges, such as those that can occur when a person touches the device or when the device is exposed to charged objects or surfaces. ESD can cause damage to electronic devices, so it is important for devices to be immune to ESD in order to ensure their proper functioning.
The tolerances for ESD immunity in automotive grade electronic devices will depend on the specific requirements of the relevant EMC standards and regulations. In general, automotive grade electronic devices are expected to be able to withstand ESD discharges of up to several kilovolts, depending on the specific application and the potential sources of ESD in the operating environment. For example, an automotive grade electronic device that is intended for use in the passenger compartment of a vehicle may be required to have a higher level of ESD immunity than a device that is intended for use in the engine compartment.
In addition to the specific requirements for ESD immunity, automotive grade electronic devices are also typically required to meet other EMC standards and requirements, such as those related to electromagnetic emissions and immunity to other forms of EMI. These requirements are typically detailed in the relevant EMC standards and regulations, and they may vary depending on the intended use and operating environment of the device.
When designing a robust electrostatic discharge (ESD) for DIMO compatible devices, there are several key steps to consider:
- 1.Conduct a thorough analysis of the device's intended environment and use case to identify potential sources of ESD and the potential effects on the device.
- 2.Design the device's hardware and software with ESD resilience in mind, using appropriate shielding, filtering, and other techniques to minimize the susceptibility of the device to ESD.
- 3.Conduct testing to verify that the device meets the relevant ESD standards and requirements. This typically involves performing ESD immunity tests to ensure that the device is able to withstand the levels of ESD that may be encountered in its intended environment.
- 4.Obtain certification from an accredited laboratory or certification body to demonstrate that the device meets the relevant ESD standards and requirements.
- 5.Implement appropriate measures to maintain the device's ESD resilience over its lifespan, including regular testing and updates to the hardware and software as needed.
In general, the goal of designing a robust ESD resilient electronic device is to ensure that the device can function properly in its intended environment without being damaged by ESD. This requires a thorough understanding of the potential sources of ESD and the appropriate design and testing techniques to minimize and mitigate these effects.
ELECTROMAGNETIC COMPATIBILITY
DIMO devices must be EMC compatible, there are several key steps to consider for a device to be approved on the DIMO network.
- Conduct a thorough analysis of the device's intended environment and use case to identify potential sources of electromagnetic interference (EMI) and the potential effects on the device.
- Design the device's hardware and software with EMC in mind, using appropriate shielding, filtering, and other techniques to minimize the generation of EMI and to ensure that the device is immune to external EMI.
- Conduct testing to verify that the device meets the relevant EMC standards and requirements. This typically involves performing both emission and immunity tests to ensure that the device does not interfere with other devices and is not affected by external EMI.
- Obtain certification from an accredited laboratory or certification body to demonstrate that the device meets the relevant EMC standards and requirements.
- Implement appropriate measures to maintain the device's EMC compliance over its lifespan, including regular testing and updates to the hardware and software as needed.
- In general, the goal of designing and certifying an EMC compatible device is to ensure that the device can function properly in its intended environment without interfering with other devices or being affected by external EMI. This requires a thorough understanding of the potential sources of EMI and the appropriate design and testing techniques to minimize and mitigate these effects.
The main tests that are used to certify a device as being electromagnetic compatibility (EMC) compliant are emission tests and immunity tests.
Emission tests are used to measure the amount of electromagnetic interference (EMI) that is generated by the device under test (DUT). These tests typically involve exposing the DUT to various electromagnetic fields and measuring the levels of EMI that are emitted by the DUT. The results of the emission tests are compared to the relevant EMC standards to determine if the DUT meets the required limits for EMI emissions.
Immunity tests are used to measure the device's ability to operate properly in the presence of external EMI. These tests typically involve exposing the DUT to various electromagnetic fields and measuring its performance and functionality under these conditions. The results of the immunity tests are compared to the relevant EMC standards to determine if the DUT is immune to external EMI.
In general, emission and immunity tests are used together to ensure that a device is both a good electromagnetic citizen (i.e. it does not generate excessive EMI) and is able to operate properly in the presence of external EMI. Depending on the specific application and intended environment for the DUT, other tests may also be performed, such as surge tests, conducted immunity tests, and radiated immunity tests.
The standards that specify the requirements for emission and immunity tests are called electromagnetic compatibility (EMC) standards. These standards are developed by various organizations, such as the International Electrotechnical Commission (IEC), the European Committee for Electrotechnical Standardization (CENELEC), and the Federal Communications Commission (FCC) in the United States.
The specific standards that apply to a given device will depend on the device's intended use and environment, as well as the applicable regulations in the region where the device will be used. For example, there are different EMC standards for medical devices, industrial equipment, and consumer electronics, and these standards may vary between different countries or regions.
In general, EMC standards specify the limits for EMI emissions and the levels of external EMI that a device must be able to withstand in order to be considered compliant. These standards may also specify the testing methods and procedures that must be used to perform emission and immunity tests, as well as the requirements for certification and labeling of compliant devices.
There are several key electrical design aspects that must be adhered to for DIMO compatible devices. All devices manufactured on the DIMO network must be ICT tested. These include:
- Test points: The device should include test points that allow for easy access to the device's circuit board for testing purposes. These test points should be clearly labeled and easy to access.
- Grounding: The device's circuit board should be properly grounded to ensure that electrical signals are accurately measured during ICT testing.
- Power supply: The device should have a stable and reliable power supply that can support the electrical demands of ICT testing.
- Signal integrity: The device's circuit board should be designed to maintain signal integrity during ICT testing to ensure accurate test results. This can include the use of high-quality components, careful routing of signals, and other design techniques.
- Compatibility with test equipment: The device should be compatible with the ICT test equipment that will be used during testing, including any necessary connectors and interfaces.
- Ease of access: The device's circuit board and components should be easy to access for testing purposes, without requiring the disassembly of the entire device. This can include the use of removable panels or other access points. \
A test plan must be established and approved for each DIMO compatible device, and the results from each individual device ICT test should be made available to the DIMO network.