CAN IDs
This document describes the messages used to transport sensor and actuator information over the ConceptCar CAN Bus. All information regarding the CAN Messages such as IDs, data width, payload and semantics are defined in this document.
CAN IDs and Description
In this section the CAN IDs used by the concept car are defined and a brief description of them is given. Later on the semantics of each message is defined.
| CAN ID | Identifier | Description |
|---|---|---|
| 0x08 | CANid_WheelSpeedFL | Wheel speed average |
| 0x09 | CANid_WheelSpeedFR | Wheel speed average |
| 0x0a | CANid_WheelSpeedRL | Wheel speed average |
| 0x0b | CANid_WheelSpeedRR | Wheel speed average |
| 0x0d | CANid_Voltage | Board supply voltage |
| 0x0e | CANid_ResetCounter | Reset logger counter |
| 0x10 | CANid_Inertial_X | Inertial System acceleration X axis |
| 0x11 | CANid_Inertial_Y | Inertial System acceleration Y axis |
| 0x12 | CANid_Inertial_Yaw | Inertial System yaw rate |
| 0x20 | CANid_SelectJumper | Select between original or generated |
| 0x22 | CANid_Steering | PWM signal for steering (transmitter signal) |
| 0x25 | CANid_Throttle | PWM signal for throttle (transmitter signal) |
| 0x32 | CANid_Steering_new | PWM signal for steering (generated) |
| 0x35 | CANid_Throttle_new | PWM signal for throttle (generated) |
| 0x400 | CANid_ErrorController | Controller error 5 (Table 5) |
| 0x402 | CANid_EmergencyKey | Emergency key pressed (Table 6) |
Semantics of CAN Messages
In this section the semantics of each CAN Message is described. Some of the messages have special quality descriptors attached to them, which are also described here. The first important definition about the CAN Messages is their size. All of the CAN Messages going over the ConceptCar CAN Bus are 32bit long. While this is not unchangeable, it is necessary to change the code to allow messages bigger than 32bits.
CANid_WheelSpeedXX
Information about wheel speed coming from the wheel speed sensors. The wheel speed is calculated using the time interval between two measures done by the speed sensor. Messages informing the vehicle speed are sent every 20ms. If no measurement is accomplished during the 20ms time slot, no speed information is available. For this reason the semantic of the messages and measurements are defined. A quality descriptor is inserted into the message to describe the quality of the information provided by the message payload, so listeners of this messages can decide what to do with the information. The speed is calculated using the average of measures obtained within the 20ms time slot. When several readings occur during the time slot, the value 2 is said to have a high quality. If the time between measures take longer than 20ms, the quality of the information is decayed and follows equation 1.
