I2C bus protocol for BL-Ctrl

This describes the I2C-Protocol for the brushless controller

The I2C-protocol is compatible to BL-Versions 2&3

Setpoint

  • Setpoint: just write the setpoint (0-255) to the BL-Ctrl
  • if you use higher resolution (11bit = 2048), just send the lower bits as second byte:

    • first, the High-Byte = SetPoint / 8;

    • second, the Low-Byte = SetPoint % 8; // note-> only the lower 3 bits are used

    • please leave the other bits in the Low-Byte to zero

BL-addresses

  • 1 = 0x50
  • 2 = 0x52
  • 3 = 0x54
  • 4...

reading

If you read from the BLs:

Read from BL-addresses (0x51, 0x53, 0x55, ...) -> the lower bit means: read now

The data comes in this order

  • current (see below)
  • state
  • Temperature in °C
  • rpm (BL V3 only)

  • voltage (BL V3 only) Note: only low-byte -> if lower than 60, just add 255 -> '5' would be 25,5V+5 = 26,0V

current

  • Value <= 200 Current reading is in 0,1A (123 = 12,3A)

  • Value > 200 Current reading is in 1A with 20A Offset (234 = 20 + 34 = 54,0A) 

unsigned int BL3_Current(unsigned char who) // in 0,1A 
{
 if(Motor[who].Current == 255) return(0); // invalid
 if(Motor[who].Current <= 200) return(Motor[who].Current); else return(200 + 10 * ((unsigned int)Motor[who].Current-200));
}

state

For the state:

  • 255 = motor running
  • 254 = motor running and operating in redundant mode
  • 250 = BL V2 ready for operation (not running)
  • 248-249 = BL V3 ready for operation (not running)
  • 50-247 = Motor running, but MaxPWM is limited (overtemperature or overcurrent)
  • 40 = starting motor
  • 39 = motor start failed
  • 1-20 = error in selftest

{i} note: the Status is sometimes also called "MaxPWM" in the sourcecodes