Spark-Max-CAN-Testing

Notes about CAN (Controller area network)

General

• Broadcast type bus. Every message is broadcast to every node on the bus. messages are filtered by identifier at start.
• Older version of CAN (1.0) only had a 11 bit identifier but new version (2.0) has 29 bit identifier. We will be using CAN 2.0.
• 3 types of frames
  • Data: Put data onto the CAN bus for everyone else.
  • Remote: Asks for some data with a specific label. Someone else on the CAN bus should respond.
  • Error: An error was detected. This frame violates framing rules so everyone on the bus will also produce an error frame.
  • Type of frame is differentiated by remote transmission request(RTR) bit.
• Each message(frame) has a maximum utility load of 94 bits
  • 29 bit identifier
  • 0-8 byte data
  • 1 bit RTR

Arbitration

• Done using the 29 bit identifier field. The lowest number has the highest priority.

Notes about interfacing with Spark Max

• SPARK Max Configuration Parameters
• FRC CAN standard

Identifier Structure

Device Type	Manufacturer	API Class	API Index	Device ID
28:24	23:16	15:10	9:6	5:0
Motor Controller: 2	REV: 5	Look below	Look below	Spark Max ID

API Class

• Speed Control Mode: 1
• Voltage Compensation Mode: 2
• Position Control Mode: 3
• Current Control Mode: 4
• Status: 5
• Periodic Status: 6
• Configuration: 7
• Ack: 8

API Index

• Enable Control: 0
• Disable Control: 1
• Set Setpoint: 2
• P Constant: 3
• I Constant: 4
• D Constant: 5
• Set Reference: 6
• Trusted Enable: 7
• Trusted Set No Ack: 8
• Trusted Set Setpoint No Ack: 10
• Set Setpoint No Ack: 11

Use external CAN controller?

Good controller MCP251863 Library acan2517fd