Revision as of 22:08, 19 March 2020

Introduction

TireX is a powerful and versatile multi-zone tire temperature sensor designed for motorsports applications.

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Features

High Performance

TireX can be configured to report up to 16 temperature zones, supporting sample rates up to 64Hz via CAN bus with the powerful embedded 32 bit processor.

Rugged and Compact

TireX features a rugged, low profile design with a wide field of view for space constrained environments.

Flexible Setup

Temperature zones and sensor calibration is customizable by the end user
Orientation can be inverted for consistent data reporting between left and right sides of vehicle by assigning a position to the sensor
CAN bus can be set for 500 or 1MB (default is 500K)

Specifications

Specifications are preliminary and subject to change

Feature	Description
Sensor type	Thermal array
Object temperature range	0 - 127.5C
Field of view	120 degrees
Accuracy	1C
Temperature zones	1 / 2 / 4 / 8 / 16
Sample rate	0.5 - 64Hz
Processing Engine	32 bit
Configurable positions	4 (Left-Front, Right-Front, Left-Rear, Right-Rear); Reversible orientation
Emissivity	Configurable (0.95 default)
Temperature compensation	Automatic
Electrical
Interface	CAN 2.0
Supply voltage	6 - 12v
Power	200mW
Harness	M8 4P Male, 250mm length
CAN bus
CAN baud rate	500K and 1M, jumper configurable (500K default)
Address space	4 separate address spaces (configurable via jumper)
Termination	No Termination (configurable via jumper)
Physical / Environmental
Construction	CNC aluminum
Dimensions	64 x 46 x 12.5mm
Weight	10 grams
Operating temperature	-40 - 85C
IP rating	IP65

Dimensions / Mounting

Electrical / CAN connection

Connection is provided by a standard industrial M8 4P male plug.

Pin	Connecton
Pin 1	CAN Low
Pin 2	Voltage supply (6-12v)
Pin 3	CAN High
Pin 4	Ground

CAN bus protocol

Overview

The CAN bus API provides the configuration and control interface for TireX

Conventions

Formula

Conversion formulas are expressed as converting the CAN encoded value to real-world value.

Example:
- Encoded value in CAN message: 95
- Formula: A / 100
- Real-world value: 0.95

Data encoding

Endian

16 and 32 bit values are encoded as little endian.

Single and mulit-byte values

Value	Symbol Reference
8 Bit values	A
16 bit values	A (low byte) / B (high byte)
32 Bit values	A (low byte) / B / C / D (high byte)

CAN Baud rate

500K and 1MB rates are supported.

500K is enabled by default; cut the jumper labeled BAUD on the bottom of TireX to enable 1MB rate.

CAN base ID

A configured TireX sensor will have a CAN base address that is a combination of the Main Base ID + Position Offset based on the installed position of the sensor on the vehicle. This combination creates a final Sensor Base ID

All broadcast and configuration CAN messages is offset from the final calculated Sensor Base ID.

Default Main Base ID

Default Main CAN base ID is 0xA100 (41216)

Adjusting Main Base ID

The base address is determined by the state of the ADR1 and ADR2 jumpers. By default, the jumpers are closed (bridged); the jumper can be opened by cutting the trace between the pads. To re-close the jumper, add a small amount of solder to bridge the gap between the pads you want to close.

Note: In the vast majority of the cases you can use the default Main Base ID of 0xA100.

ADR2 Jumper	ADR1 Jumper	Address
Closed	Closed	0xA100 (41216)
Closed	Open	0xB100 (45312)
Open	Closed	0xC100 (49408)
Open	Open	0xD100 (53504)

Opening the jumper ADR1 will add (0x1000) 4096 to the base ID
Opening the jumper ADR2 will add (0x2000) 8192 to the base ID
Opening both jumpers ADR1 and ADR2 will add (0x3000) 12288 to the base ID.

Sensor Position Offset

The sensor position will offset the Main Base ID by the position of the sensor as defined in the table, to set the final Sensor Base ID

Position ID	Sensor Position	Offset
0	Left-Front	0x0 (0)
1	Right-Front	0x100 (256)
2	Left-Rear	0x200 (512)
3	Right-Rear	0x300 (768)

Example: default base address (0xA100)

Sensor Position	Final Sensor Base ID
Left-Front	0xA100
Right-Front	0xA200
Left-Rear	0xA300
Right-Rear	0xA400

CAN Messages

The announcement message is broadcast by TireX once per second for 10 seconds upon power up.

Address

CAN ID: Sensor Base ID + 0

Offset	What	Data Type	Formula	Value
0	Sample Rate	unsigned	A * 1	Sample Rate (Hz)
1	Temperature Zones	unsigned	A * 1	Number of configured temperature zones (1 / 2 / 4 / 8 / 16)
2	Sensor Position	Unsigned	A * 1	Configured sensor position (0=Left-Front / 1=Right-Front / 2=Left-Rear / 3=Right-Rear)
3	Reserved
4	Reserved
5	Major Version	unsigned	A * 1	Firmware Major Version Number
6	Minor Version	unsigned	A * 1	Firmware Minor Version Number
7	Patch Version	unsigned	A * 1	Firmware Patch version number

Statistics

Broadcast by TireX every 10 seconds.

Address

CAN ID: Sensor Base ID + 2

Offset	What	Data Type	Formula	Value
0	Current Sample Rate	unsigned	A * 1	0.5 - 64Hz (0 = 0.5Hz)
1	Reserved
2	Reserved
3	Reserved
4	Reserved
5	Major Version	unsigned	A * 1	Firmware Major Version Number
6	Minor Version	unsigned	A * 1	Firmware Minor Version Number
7	Patch Version	unsigned	A * 1	Firmware Patch version number

Configuration Preferences

This message is broadcasted to TireX to configure the sensor's preferences.

Address

CAN ID: Sensor Base ID + 3

Offset	What	Data Type	Formula	Value
0	Sample Rate	unsigned	A * 1	Rate to report sensor values ( 0.5 - 64Hz). Valid sample rates: 0 (0.5Hz) / 1 (1Hz) / 2 (2Hz) / 4 (4Hz) / 8 (8Hz) / 16 (16Hz) / 32 (32Hz) / 64 (64Hz). Specifying an invalid value will select the default value of 16
1	Temperature zones	unsigned	A * 1	Number of temperature zones. Valid zones: 1 / 2 / 4 / 8 / 16. Specifying an invalid value will select the default value of 4.
2	Sensor Position	unsigned	A * 1	Location of the sensor on the vehicle. This position adjusts the Sensor Base ID. Valid Positions 0 (Left-Front) / 1 (Right-Front) / 2 (Left-Rear) / 3 (Right-Rear). Specifying an invalid value will select the default value of 0 (Left-Front). Note: The sensor position affects the orientation of the sensor zones. Sensor Position 1 and 3 will report temperature zones left - right; Position 0 and 2 will report temperature zones right - left.
3	Reserved
4	Reserved
5	Reserved
6	Reserved
7	Reserved

Calibration Preferences

This message is broadcasted to TireX to configure the sensor's calibration.

Address

CAN ID: Sensor Base ID + 4

Offset	What	Data Type	Formula	Value
0	Emissivity	unsigned	A / 100	Emissivity of the target. Default is 0.95
1	Reserved
2	Reserved
3	Reserved
4	Reserved
5	Reserved
6	Reserved
7	Reserved