Designing a Fast & Secure
OBD Scan System using Mistral i.MX6 Nano SOM
Application Note
Overview
On-Board Diagnostic systems were introduced by
Automotive OEMS in late '70s & early 1980's enabling
electronic means to control engine functions and
diagnose engine problems. Though OBD systems are
primarily intended to meet EPA emission standards,
with the introduction of OBD-II, on-board diagnostic
systems have become more sophisticated, providing
almost complete engine control & monitoring for parts
of the chassis, body and accessory devices, as well as
the control network of the car. OBD-II became a
universal inspection and diagnosis method for vehicle
diagnostics and most recent automobiles are OBD-II
compliant providing a standard interface to collect data
from engine sensors, using a Scantool. Fast & secure
boot-up, small form-factor and quick processing and
dissemination of data are few crucial parameters
expected from an OBD Scantool.
This application note gives a technical perspective on
how Mistral i.MX6 Nano SOM can be adapted to meet
the technical and functional requirements, along with
an OBD-to-RS232 Interpreter [ELM327] for designing
the core architecture of an OBD Scantool.
i.MX6 Nano SOM -
The Nano SOM from Mistral is a small form factor, high
performance, low cost, ready-to-use System on Module
(SOM) built around the powerful 800MHz Quad/Dual
Core i.MX6 SoC from NXP. The i.MX6 offers extensive
integration capability such as dual camera, LCD, PCIe,
HDMI output, NOR flash, Ethernet, Audio and an easily
deployable architecture that favours fast time-to-market.
Features
Hardware
! i.MX6D/Q800MHz ARM Cortex- A9 processor
! 1GB LPDDR2 PoP memory
! Wi-Fi + BT 4.0 Module
! 8GB eMMC
! Can be operated by powering up from a battery
! Weighs 8 Grams
Software
! Linux Kernel 4.1
! Android
! Yocto BSP
! u-Boot 2015.04
Basic Configuration
Design Considerations
Let's now look at the elements that need attention while
designing the electronics sub-system for an OBD-II
Scantool. The latest trend being miniaturisation and giving
maximum power to handheld scan devices, the electronic
sub-system of a Scantool needs to be very compact in
size, light-weight, battery operated while having high
processing capability. The i.MX6 Nano SOM is a high-
performance unit which meets the above mentioned
essential parameters. The recommended OBD-to-RS-
232 interpreter ELM327 is designed to act as a bridge
between the On-Board Diagnostics (OBD) ports of the
vehicle and the standard serial interface of the Scantool.
Additionally, in order to automatically detect and interpret
nine OBD protocols, the ELM327 also provides support
for high-speed communication, a low power sleep mode,
and the J1939 truck and bus standard. ELM327
communicates with the Nano SOM over RS232 serial
connection. Using terminal programs you can
send/receive data from the interpreter.
The Nano SOM has i.MX6D/Q core processor, which
provides high processing power and Wi-Fi/BT module
through which the interpreted data can be streamed.
ELM327 detects and captures data from the automobile
unit, which is interpreted, processed and converted into
packet data and transferred to i.MX6 Nano SOM. Data
received from ELM327 is fine-processed and send to a
LCD display powered by the Nano SOM or streamed over
WiFi/BT to suit the client application.
Software Design & Integration
The Linux based Yocto Jethro runs on the i.MX6 Nano
SOM, evokes a multithreaded environment to speed the
task execution. Yocto Jethro with its low latency and high
accuracy supports near real-time access to rapidly
changing data. Yocto Jethro can be customized according
to the Scantool requirements in order to improve the
overall throughput of the device.
The information gathered is analysed and displayed in the
LCD display mounted on the device. The low level system
software read the data from vehicle through OBD
connector using OBD-II PIDs, decodes the data as per the
OBD-II standards. Once the PID is entered, the scan tool
sends it to the vehicle's controller–area network (CAN)-
bus. A device on the bus recognizes the PID and reports
the value for that PID to the bus. The scan tool reads the
response, and displays it over the LCD or streams the
data to Mobile Application over Wi-Fi or Bluetooth to the
technician or car owner. The results can also be viewed on
custom application running on PC's and Mobiles.
A user-friendly GUI is key to the commercial success of
the Scantool. The developer can design intuitive Qt based
application that provides a user friendly interface for
Scantool. Qt provides the flexibility to develop integrated
applications for embedded, mobile, desktop and
touchscreen devices.
Product Implementation Approach
The diagram below showcases the fundamental
architecture of the Scantool using Nano SOM. The Nano
SOM by default has all the key functional components
required for the faster dissemination of data to client in its
original design. This is a huge advantage for the
developer, save time and cost as no customisation is
warranted on the Nano SOM to meet the system
requirement.
i.MX6D/Q
LPDDR2
(PoP)
Wireless module
Wi-Fi/BT
Storage-
eMMC
PMIC
Expansion Connectors
Nano SOM Architecture
The carrier board that carries the core architecture of the
Scantool needs to be custom designed. The carrier
module should comprise Display, Audio and Video,
Ethernet, Wireless and other interfaces as required.
Preferred interfaces on the carrier module:
! Display interfaces such as LVDS and touch interface,
MIPI DSI display with Touch control
! Audio interfaces for Voice Alerts
! MicroSD connector for expandable memory
! USB2.0 Host
! Ethernet & Wireless
! Debug Support
The i.MX6 Nano SOM comes with the following
software functionalities
! Linux Kernel with support for various interfaces like
I2C, MIPI, CSI, GPIO, SPI, UART, SD/MMC, Ethernet,
Display Sub-system, USB Host and USB OTG
! Support for WLAN and Bluetooth Stack
! Support for 9-axis sensor
! Support for SD and eMMC boot
! QT support for application development
! Security features which can be enabled to
protect data.
Transfer of Car Engine Data to i.MX6 Nano SOM thru ELM 327
Benefits to the customer by using
Nano SOM
! Powerful Quad/Dual Core ARM Cortex-A9 Processor
ensures fast & secure boot up
! Comes with sufficient memory and power required
for getting the OS and peripheral functionalities
mapped
! Wi-Fi IEEE802.11 a/b/g/n paves way for video
streaming
! BT4.0 for short range communications
! Small form factor (44mm x 26mm) & Light-weight
module weighing just 7.0 grams enables the
customer design relatively small & user-friendly
devices
Quick to Market - Leverage over Mistral
VISE Board
Mistral VISE board is a powerful i.MX6 development platform
built around the i.MX6 Nano SOM. Product developers can
accelerate their OBD Scantool development by developing the
custom software and applications on the VISE Board while the
custom carrier board is getting built. This will help complete the
product development and testing faster, saving cost and time.
About Mistral
Mistral is a technology design and systems engineering company providing end-to-end solutions for product
design and application deployment. Mistral is focused in three business domains: Product Engineering
Services, Aerospace & Defense and Homeland Security. Mistral provides total solutions for a given
requirement, which may include hardware design, embedded software development, systems integration and
customized turnkey solutions. Mistral's strategic partnerships with leading technology companies help provide
customers with a comprehensive package of end-to-end solutions.
Mistral's Product Engineering Services are delivered through a proven development process, designed for
embedded product development. Mistral's hardware and software team works together in a seamless manner
providing expert product designs covering board and FPGA Designs, BSP & Firmware developments,
Embedded Application developments, integration of 3rd party solutions, Verification/Validation, Product
prototyping, Production coordination and Product Sustenance services.w
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Mistral's Expertise
Mistral can provide development services to the clients to build a custom carrier board around Nano SOM
and assimilate ELM327. Board can be designed to suit the end product basis the clients need. Mistral offers
System software and application development services considering the various applications of the device.
Mistral's expert team of engineers have helped several customers realize their Product designs with the
development of smart, compact and power efficient electronics systems and the related software for the
same (BSP and Apps). Mistral's expertise in Product Development includes embedded applications,
software design and development, multi-sensor integration, wireless connectivity, power and battery
management, design of hardware for small form factor and multi-board designs, cloud/web application
development services and FCC, CE, UL Certification.