STN1110 Multiprotocol OBD-II to UART Interpreter IC

On-Board Diagnostics, Second Generation (OBD-II) is a set of standards for implementing a computer based system to control emissions from vehicles. It was first introduced in the United States in 1994, and became a requirement on all 1996 and newer US vehicles. Other countries, including Canada, parts of the European Union, Japan, Australia, and Brazil adopted similar legislation. A large portion of the modern vehicle fleet supports OBD-II or one of its regional flavors.

Among other things, OBD-II requires that each compliant vehicle be equipped with a standard diagnostic connector (DLC) and describes a standard way of communicating with the vehicle’s computer, also known as the ECU (Electronic Control Unit). A wealth of information can be obtained by tapping into the OBD bus, including the status of the malfunction indicator light (MIL), diagnostic trouble codes (DTCs), inspection and maintenance (I/M) information, freeze frames, VIN, hundreds of real-time parameters, and more.

STN1110 is an OBD to UART interpreter that can be used to convert messages between any of the OBD-II protocols currently in use, and UART. It is fully compatible with the de facto industry standard ELM327 command set. Based on a 16-bit processor core, the STN1110 offers more features and better performance than any other ELM327 compatible IC.

Feature Highlights

• Fully compatible with the ELM327 AT command set
• Extended ST command set
• UART interface (baud rates from 38 bps to 10 Mbps)
• Secure bootloader for easy firmware updates
• Superior automatic protocol detection algorithm
• Large memory buffer
• Voltage input for battery monitoring
• Available in SPDIP, SOIC and QFN-S packages
• RoHS compliant

Stability

• Solid, field-tested software. STN1110 runs the same proven code that powers the popular OBDLink family of PC-based OBD interfaces. Thanks to its large user base, any problems are discovered and corrected quickly.
• Large OBD message buffer. STN1110 has over five times as much RAM as its nearest competitor, virtually eliminating BUFFER OVERFLOW errors.
• Automatic protocol detection algorithm is continuously fine-tuned to insure that STN1110 will connect to the widest array of vehicles, even those that do not fully conform to the OBD standard.

PowerSave Sleep/Wakeup Triggers

The diagram shows the various triggers available in the STN11xx family of ICs. Please refer to the STN11xx PowerSave Functionality documentation for more details.

• All legislated OBD II protocols:
  • ISO 15765-4 (CAN 250/500 kbps, 11/29 bit)
  • ISO 14230-4 (Keyword Protocol 2000)
  • ISO 9141-2 (Asian, European, Chrysler)
  • SAE J1850 VPW (GM)
  • SAE J1850 PWM (Ford)
• Non-legislated OBD protocols:
  • ISO 15765
  • ISO 11898 (raw CAN)
• SAE J1939 OBD protocol used in heavy-duty vehicles

STN IC Comparison Chart

	STN1110	STN1170	STN2100	STN2120
UART interface
Compatible with ELM327 AT command set
Extended ST command set
PowerSave™ sleep/wake triggers
Secure bootloader
Automatic protocol detection algorithm
RAM	8k	8k	32k	32k
Flash	128k	128k	256k	256k
Performance (MIPS)	40	40	70	70
Suppors all legislated OBD-II protocols
GM Single-Wire CAN (SW-CAN)
Medium-Speed CAN (MS-CAN)
J1939
Advanced security options
Recommended for new designs
Unit pricing (10k pieces; USD)	$6.80	$7.78	$6.80	$7.78