Imported from GitHub: wjklimek1/CAN_motor_controller · commit 8830bf3 · license MIT

Description

H-bridge for DC motor controlled by CAN or PWM

README

CAN motor controller

This project is a device that allows control of DC motor by commands on CAN bus. It is based on STM32F103 microcontroller that interprets CAN messages and drives motor using two BTN8982 half-bridges configured as a single H-bridge.

Motor driving capabilities

DC motor is controlled with 21kHz PWM signal with 0-100% duty. PWM can be regulated in 0.1% steps - from 0 to 1000. Theoretically max current that MOSFETs can handle is 55A, but it can be futher limited by traces width and connectors. It was tested up to 10A, but should handle much more without any problems. Power supply voltage range is 5-24V.

Parameter	Min	Max
voltage	5V	24V
motor current		55A (10A tested)

Motor is accelerated slowly by changing PWM duty. If received command orders to immediately set PWM to 100% from 0%, duty is increased slowly in default 10ms intervals. Therefore spinning motor to top speed will take 10s. This property can be disabled by setting "motor inertia" parameter to 0 (see CAN commands table).

CAN configuration

CAN bus in STM32F103 runs on 250kb/s by default. It can be set to other, hard coded value in the initialization function. Other supported baudrates are 500kb/s and 1Mb/s.

Heartbeat

Device emits "heartbeat" frame every 1s. It is an empty frame with ID = 0x444. Heartbeat can be disabled or it's period can be changed in 1s steps up to 255s.

CAN message structure

Device utilizes two identifiers - 0x444 for commands and 0x445 for requesting data. This values are hard coded too, but can be changed in canbus.h file. DLC of CAN messages is not really important, but it cannot be shorter than expected. In both commands and data requests first byte of message is code of command or data request. In commands next bytes represent values of command parameters. When data request is received by device, it will respond with frame of the same ID and data request code. Next bytes will contain requested data.

Commands

Following table shows available commands:

Command	frame ID	DLC	byte 0 (command code)	byte 1	byte 2	byte 3
Set speed	0x444	4	1	rotation direction (0 or 1)	MSB of speed	LSB of speed
Set max temperature internal	0x444	2	2	max internal temperature (uint8_t) in Celcius	-	-
Set max temperature external	0x444	2	3	max external temperature (uint8_t) in Celcius	-	-
Set max current	0x444	4	4	MSB of max current (mA)	LSB of max current (mA)	-
Emergency stop	0x444	1	5	-	-	-
Set inertia	0x444	2	6	Inertia (ms delay between changing PWM duty)	-	-
Set heartbeat	0x444	2	7	heartbeat interval (0 for disabled)	-	-

Data requests

To request data, frame of ID = 0x445 and first byte containing data request code can be sent. Device will respond with similar frame, but containing data in next bytes.

Following table shows available data requests:

Data request	frame ID	DLC	byte 0 (data request code)	byte 1	byte 2	byte 3	byte 4	byte 5
Internal temperature	0x445	2	1	Internal temperature (uint8_t) in	Celcius	-	-	-
External temperature	0x445	2	2	External temperature (uint8_t) in	Celcius	-	-	-
Power supply voltage	0x445	3	3	MSB of voltage in mV	LSB of voltage in mV	-	-	-
Motor current	0x445	3	4	MSB of current in mA	LSB of current in mA	-	-	-
Speed	0x445	4	5	rotation direction (0 or 1)	MSB of speed	LSB of speed	-	-
Target speed	0x445	4	6	rotation direction (0 or 1)	MSB of speed	LSB of speed	-	-
Errors	0x445	5	7	MOSFET fault	overcurrent	overtemperature internal	overtemperature external	emergency stop