TireX

From Autosport Labs
Jump to: navigation, search

Introduction

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

Upcoming Product

TireX pre-orders are starting soon: sign up to get notified when pre-orders launch
Tirex 3quarter.jpg

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
  • Sensor position can be assigned to provide consistent data reporting between left and right sides of vehicle.
  • 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
Sensor Resolution 16 x 12 (196 pixels)
Object temperature range 0 - 127.5C (tire temperature mode) / 0 - 255C (full frame mode)
Field of view 110 x 75 degrees
Accuracy 1C
Temperature zones (tire) 1 / 2 / 4 / 8 / 16
Sample rate 0.5 - 64Hz (Tire temperature mode) 0.5 - 10Hz (Full frame mode)
Processing Engine 32 bit
Configurable positions 4 (Left-Front, Right-Front, Left-Rear, Right-Rear); Reversible orientation
Emissivity Configurable (0.95 default)
Ambient temperature compensation Automatic (adjustable offset)
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

TireX dimensions.png

Mounting Distance

TireX has a wide aspect ratio of 110 degrees, so you can use some trigonometry to calculate the distance. Here are some examples:

  • 205 width = 71mm
  • 225 width = 79mm
  • 235 width = 82mm
  • 245 width = 85mm
  • 255 width = 89mm
  • 275 width = 96mm
  • 315 width = 110mm

Here's a convenient online calculator

Tip: you can mount TireX at a further distance if you use the middle channels. Example:

  • if only using 8 channel, you can mount 2x the distance
  • If only using 4 channels, you can mout 4x the distance
  • Note: 4 channels is often the resolution of choice to reduce the bulk of data generated, and gives perfectly adequate results for determining tire performance.

Electrical / CAN connection

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

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

Zone Configuration

Up to 16 configurable temperature zones

TireX can be configured to report up to 16 temperature zones across the sensor's entire field of vision.

When configured for 2 or more zones, temperature for zones are reported in the order of inside through outside edge.

Zones Coverage
1 Averaged across the entire field of vision
2 Each zone averaged across 1/2 the field of vision
4 Each zone averaged across 1/4 the field of vision
8 Each zone averaged across 1/8 the field of vision

Reversible orientation based on sensor position

TireX zones are reversed based on the configured sensor position (left vs right side) to allow identical physical sensor mounting orientation between sides. TireX zones.jpg

CAN bus protocol

Overview

The CAN bus API provides the configuration, control and sensor broadcast 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.

Announcement

CAN ID: Sensor Base ID + 0

Offset What Data Type Formula Value
0 Sample Rate unsigned A * 1 0.5 - 64Hz (0 = 0.5Hz)
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.

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.

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 Frame mode unsigned A * 1 0 = Standard (Tire Temperature) mode; 1 = Full Frame mode
4 Reserved
5 Reserved
6 Reserved
7 Reserved

Calibration Preferences

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

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 Ambient temperature compensation unsigned A * 1 Value in C
2 Sensor Resolution unsigned 16-19 Sensor ADC resolution, in bits
3 Reserved
4 Reserved
5 Reserved
6 Reserved
7 Reserved

Sensor Temperature Value Broadcast

The following messages will contain the temperature values based on the number of temperature zones configured, broadcast at the currently configured sample rate.

  • Note: The sensor position affects the orientation of the sensor zones:
    • Position 1 and 3 will report temperature zones left - right;
    • Position 0 and 2 will report temperature zones right - left.

1 Zone

CAN ID: Sensor Base ID + 0x20 (32)

Offset What Data Type Formula Value
0 Zone 1 value unsigned A / 2 0 - 127.5C

2 Zones

CAN ID: Sensor Base ID + 0x20 (32)

Offset What Data Type Formula Value
0 Zone 1 value unsigned A / 2 0 - 127.5C
1 Zone 2 value unsigned A / 2 0 - 127.5C

4 Zones

CAN ID: Sensor Base ID + 0x20 (32)

Offset What Data Type Formula Value
0 Zone 1 value unsigned A / 2 0 - 127.5C
1 Zone 2 value unsigned A / 2 0 - 127.5C
2 Zone 3 value unsigned A / 2 0 - 127.5C
3 Zone 4 value unsigned A / 2 0 - 127.5C

8 Zones

CAN ID: Sensor Base ID + 0x20 (32)

Offset What Data Type Formula Value
0 Zone 1 value unsigned A / 2 0 - 127.5C
1 Zone 2 value unsigned A / 2 0 - 127.5C
2 Zone 3 value unsigned A / 2 0 - 127.5C
3 Zone 4 value unsigned A / 2 0 - 127.5C
4 Zone 5 value unsigned A / 2 0 - 127.5C
5 Zone 6 value unsigned A / 2 0 - 127.5C
6 Zone 7 value unsigned A / 2 0 - 127.5C
7 Zone 8 value unsigned A / 2 0 - 127.5C

16 Zones

CAN ID: Sensor Base ID + 0x20 (32)

Offset What Data Type Formula Value
0 Zone 1 value unsigned A / 2 0 - 127.5C
1 Zone 2 value unsigned A / 2 0 - 127.5C
2 Zone 3 value unsigned A / 2 0 - 127.5C
3 Zone 4 value unsigned A / 2 0 - 127.5C
4 Zone 5 value unsigned A / 2 0 - 127.5C
5 Zone 6 value unsigned A / 2 0 - 127.5C
6 Zone 7 value unsigned A / 2 0 - 127.5C
7 Zone 8 value unsigned A / 2 0 - 127.5C

CAN ID: Sensor Base ID + 0x21 (33)

Offset What Data Type Formula Value
0 Zone 9 value unsigned A / 2 0 - 127.5C
1 Zone 10 value unsigned A / 2 0 - 127.5C
2 Zone 11 value unsigned A / 2 0 - 127.5C
3 Zone 12 value unsigned A / 2 0 - 127.5C
4 Zone 13 value unsigned A / 2 0 - 127.5C
5 Zone 14 value unsigned A / 2 0 - 127.5C
6 Zone 15 value unsigned A / 2 0 - 127.5C
7 Zone 16 value unsigned A / 2 0 - 127.5C

Full Frame Mode

CAN ID: Sensor Base ID + 0x40 (64)

  • Note: Pixels increment linearly by row x column
Offset What Data Type Formula Value
0 Pixel 0 value unsigned A 0 - 255C
... ... ... ... ...
191 Pixel 191 value unsigned A 0 - 255C