Bebop/BLDC
General
The BLDC of the Bebop is the Brushless Driver Controller that controls all 4 brushless motors from the Bebop. This BLDC contains a closed loop RPM controller, and also reads out the battery voltage.
Protocol
- 0x02 SET_REF_SPEED
- 0x20 GET_OBS_DATA
- 0x40 START_PROP
- 0x4D TOGGLE_GPIO
- 0x60 STOP_PROP
- 0x80 CLEAR_ERROR
- 0x82 PLAY_SOUND
- 0xA0 GET_INFO
SET_REF_SPEED (0x02)
Sets the RPM reference of the motors.
Arguments: 9 bytes
- 0-1: RPM reference Left Front motor (uint16)
- 2-3: RPM reference Right Front motor (uint16)
- 4-5: RPM reference Right Back motor (uint16)
- 6-7: RPM reference Left Back motor (uint16)
- 8: Reserved (0x00)
GET_OBS_DATA (0x20)
Gets the observed data from the motors and battery.
Arguments: 0 bytes Receive: 8 bytes or 13 bytes
- 0-1: RPM observed Left Front motor (uint16)*
- 2-3: RPM observed Right Front motor (uint16)*
- 4-5: RPM observed Right Back motor (uint16)*
- 6-7: RPM observed Left Back motor (uint16)*
- 8-9: Battery voltage in mV (uint16)
- 10: Status (uint8)
- 11: Errno (uint8)
- 12: Temperature in degrees Celcius (uint8)
* Bit 15 is reserved for detecting maximum RPM (depending on voltage and altitude)
Status
- 0: Init
- 1: Idle
- 2: Ramping
- 3/4: Spinning
- 5: Stopping
- 6: Suicided
Errno
- 0: No error
- 2: Motor stalled
- 3: Propeller security
- 4: Communication lost
- 9: Battery voltage too low
START_PROP (0x40)
Starts the propellers. The propellers will not start when the current error is not cleared.
Arguments: 0 bytes or 1 byte
- 0: Motor bitmask (0000ABCD, A:Left Upper, B:Right Upper, C: Right Back, D: Left Back) where 1 is clockwise and 0 is counterclockwise
Receive: 0 bytes
TOGGLE_GPIO (0x4D)
Toggle GPIO outputs. The reset will put the BLDC into bootloader mode.
Arguments: 1 byte
- 0: GPIO bitmask (bit 0: Reset, bit 1: Red LED, bit 2: Green LED)
Receive: 0 bytes
STOP_PROP (0x60)
Stop the propellers when turning.
Arguments: 0 bytes Receive: 0 bytes
CLEAR_ERROR (0x80)
Clear the current error.
Arguments: 0 bytes Receive: 0 bytes
PLAY_SOUND (0x82)
Play a sound. A negative number will loop the sound.
Arguments: 1 byte
- 0: Sound number (0: None, 1: Short beep, 2: Boot beep, 3: Be-Bop-Ah-Lula, negative: repeat) (int8)
Receive: 0 bytes
GET_INFO (0xA0)
Get information about the BLDC.
Arguments: 0 bytes Receive: 4 bytes or 13 bytes
- 0: Software version (major)
- 1: Software version (minor)
- 2: Software type
- 3: Number of motors
- 4-5: Number of flights (uint16)
- 4-5: Time last flight (uint16)
- 6-9: Full flight time (uint32)
- 10: Last error code
Checksum
For all the packets with arguments or where we receive bytes there is a checksum byte at the end. This checksum is a simple XOR algorithm including the first command byte.
checksum = CMD_BYTE;
for(int i = 0; i < packet_size; i++)
checksum = checksum ^ packet[i];
Credits to Christophe de Wagter for figuring out the Checksum.