CommunityForumWikiBlogLearn
Go Back
Direct-drive Servo Motor

Reference

This article details the communication protocols for operating motors, including UART interface parameters, command structures, operation steps, and protection regulations to ensure safe and efficient motor operation.

Communication Protocol Description

Basic Protocol Parameters

Interface Baud rate Data bit Stop bit Parity bit Data length
UART 115200 8bit 1bit None 10byte

Key Specifications

Response format: One question and one answer

Rate: Up to 500Hz

In speed loop mode: -2100 ~ 2100 corresponds to -210rpm ~ 210rpm, data type is signed 16 bits

In position loop mode: 0 ~ 32767 corresponds to 0° ~ 360°, data type is unsigned 16 bits

Operation steps:

①Set motor ID (save when power off)

②Set motor mode (open loop, speed loop, position loop, default is speed loop)

③Send given value

Detailed Communication Commands

1. Drive the motor to rotate

Send to the motor:

Data domain DATA[0] DATA[1] DATA[2] DATA[3] DATA[4] DATA[5] DATA[6] DATA[7] DATA[8] DATA[9]
Content ID 0x64 Speed/position given high 8 bits Speed/position given low 8 bits 0 0 Acceleration time Braking 0 CRC8

Motor feedback:

Data domain DATA[0] DATA[1] DATA[2] DATA[3] DATA[4] DATA[5] DATA[6] DATA[7] DATA[8] DATA[9]
Content ID 0x64 Speed high 8 bits Speed low 8 bits Current high 8 bits Current low 8 bits Acceleration time Temperature Fault code CRC8

Acceleration time: valid in speed loop mode, acceleration time per 1rpm, unit is 1ms, when set to 1, acceleration time per 1rpm is 1ms, when set to 10, acceleration time per 1rpm is 10*1ms=10ms, when set to 0, the default is 1, acceleration time per 1rpm is 1ms

Winding temperature: unit ℃

Brake: 0XFF Other values do not brake, valid in speed loop mode

CRC8 value:

The value after CRC8 check of DATA[0]~DATA[8].

CRC algorithm: CRC-8/MAXIM

Polynomial: x8 + x5 + x4 +1

You can calculate the check digit through this website: https://crccalc.com/

For example: 01 64 01 F4 00 00 00 00 00 C3 (50rpm)

Check Graph

2. Get other feedback

Send to the motor:

Data Field DATA[0] DATA[1] DATA[2] DATA[3] DATA[4] DATA[5] DATA[6] DATA[7] DATA[8] DATA[9]
Content ID 0x74 0 0 0 0 0 0 0 CRC8

Motor feedback:

Data field DATA[0] DATA[1] DATA[2] DATA[3] DATA[4] DATA[5] DATA[6] DATA[7] DATA[8] DATA[9]
Content ID 0x74 Mileage lap high 8 bits Mileage lap second high 8 bits Mileage lap second low 8 bits Mileage lap low 8 bits Position high 8 bits Position low 8 bits Fault code CRC8

Mileage lap: lap range - 2,147,483,647 to 2,147,483,647, reset to 0 after power on

Position value: 0 ~ 32767 corresponds to 0 ~ 360°

Fault code:

Fault code BIT7 BIT6 BIT5 BIT4 BIT3 BIT2 BIT1 BIT0
Content Reserved Over/under voltage fault Reserved Overtemperature fault Stall fault Reserved Overcurrent fault Hall fault

For example, the fault code is: 0x02, which is 0b00000010, indicating an overcurrent fault

3. Motor mode switching

Sent to the motor:

Data domain DATA[0] DATA[1] DATA[2] DATA[3] DATA[4] DATA[5] DATA[6] DATA[7] DATA[8] DATA[9]
Content ID 0xA0 Mode value 0 0 0 0 0 0 CRC8

Motor feedback:

Data domain DATA[0] DATA[1] DATA[2] DATA[3] DATA[4] DATA[5] DATA[6] DATA[7] DATA[8] DATA[9]
Content ID 0xA0 Mode value 0 0 0 0 0 0 CRC8

Mode value:

0x00: Set to open loop

0x02: Set to speed loop

0x03: Set to position loop

4. Motor ID setting

Send to motor:

Data field DATA[0] DATA[1] DATA[2] DATA[3] DATA[4] DATA[5] DATA[6] DATA[7] DATA[8] DATA[9]
Content 0xAA 0x55 0x53 ID 0 0 0 0 0 CRC8

Motor feedback:

Data field DATA[0] DATA[1] DATA[2] DATA[3] DATA[4] DATA[5] DATA[6] DATA[7] DATA[8] DATA[9]
Content ID 0x64 0 0 0 0 0 0 0 CRC8

Note: When setting the ID, please ensure that there is only one motor on the bus. Only one setting is allowed per power-on. The motor will be set after receiving 5 ID setting instructions.

5. Get mode feedback

Send to motor:

Data field DATA[0] DATA[1] DATA[2] DATA[3] DATA[4] DATA[5] DATA[6] DATA[7] DATA[8] DATA[9]
Content ID 0x75 0 0 0 0 0 0 0 CRC8

Motor feedback:

Data field DATA[0] DATA[1] DATA[2] DATA[3] DATA[4] DATA[5] DATA[6] DATA[7] DATA[8] DATA[9]
Content ID 0x75 Mode value 0 0 0 0 0 0 CRC8

0x00: Open loop

0x02: Speed loop

0x03: Position loop

6. Get version number feedback

Send to motor:

Data field DATA[0] DATA[1] DATA[2] DATA[3] DATA[4] DATA[5] DATA[6] DATA[7] DATA[8] DATA[9]
Content ID 0xFD 0 0 0 0 0 0 0 CRC8

Motor feedback:

Data field DATA[0] DATA[1] DATA[2] DATA[3] DATA[4] DATA[5] DATA[6] DATA[7] DATA[8] DATA[9]
Content ID 0xFD Year Month Day Motor Model Software Version Hardware Version Reserved CRC8

Year/Month/Day: By default, 20 of 20XX is omitted, for example: 2021 is 0x15, November is 0x0B, and the 28th is 0x1C

UART Instruction Set

  1. Switch speed loop (02), this instruction has no feedback
    01 A0 02 00 00 00 00 00 00 E4
  2. Get motor mode
    01 75 00 00 00 00 00 00 00 47
  3. Brake command, valid in speed loop mode
    01 64 00 00 00 00 00 FF 00 D1
  4. ID setting (01), send this command five times in a row
    AA 55 53 01 00 00 00 00 00 00
  5. ID query
    C8 64 00 00 00 00 00 00 00 DE
  6. Speed loop command (-2100 ~ 2100 corresponds to -210~210 rpm)
    01 64 FE 0C 00 00 00 00 00 16 (-50rpm) // Calculation method: FFFF-01F4+1=FE0C, reverse other speeds and so on
    01 64 FC 18 00 00 00 00 00 EB (-100rpm)
    01 64 F8 30 00 00 00 00 00 08 (-200rpm)
    01 64 00 00 00 00 00 00 00 50 (0rpm)
    01 64 01 F4 00 00 00 00 00 C3 (50rpm) //Calculation method: 50rpm=500=01F4, and the same applies to other speeds in forward rotation
    01 64 03 E8 00 00 00 00 00 9F (100rpm)
    01 64 07 D0 00 00 00 00 00 27 (200rpm)
  7. Position loop command (0-32767 corresponds to 0-360°)
    01 64 00 00 00 00 00 00 00 50 （0°）
    01 64 20 00 00 00 00 00 00 BF （90°）//Calculation method: 90°=32767/360*90= ( Integer ) 8192（0x2000）, and the same applies to other angles
    01 64 40 00 00 00 00 00 00 97 （180°）
    01 64 60 00 00 00 00 00 00 78 （270°）
    01 64 7F FF 00 00 00 00 00 97 （360°）

Protection regulations

  1. Bus overcurrent protection threshold: 2.8A, overcurrent duration exceeds 5S to trigger shutdown protection, and is released after 5S

  2. Motor overtemperature protection threshold:

    • 80℃, shutdown protection is triggered when the temperature is higher than 80℃, and protection is automatically released when it is lower than the threshold by 5℃
    • -25℃, shutdown protection is triggered when the temperature is lower than -25℃, and protection is automatically released when it is higher than the threshold by 5℃

  3. Stall protection: protection is triggered when the stall duration exceeds 5S, and is released after 5S

  4. Overvoltage protection threshold:

    • 28V, shutdown protection is triggered when the voltage is higher than 28V, and protection is automatically released when it is lower than the threshold by 0.5V
    • 9V, shutdown protection is triggered when the voltage is lower than 9V, and protection is automatically released when it is higher than the threshold by 0.5V

Was this article helpful?

ON THIS PAGE

TOP