EVC Autonomous - Electrical

Autonomous Project electrical stack code

State Machine

CAN messages

• ID = 0x100 - Control commands (RX)
  • Byte 0-1: throttle ERPM (uint16_t, little endian), 0-AUTONOMOUS_ERPM_MAX (0 = full stop, AUTONOMOUS_ERPM_MAX = max speed)
  • Byte 2-3: steering representation (uint16_t, little endian), 0-1000, where 500 = straight, 0 = full left, 1000 = full right
  • Byte 4-7: reserved / future use
• ID = 0x101 - Status update (TX)
  • Byte 0: state machine mode + rc mode
    • Bits0-3 = state machine mode (see logic.h::logic_mode_t)
    • Bit4-5 = Mode (0 = RC, 1 = autonomous, 2 = idle)
    • Bits6-7 = reserved
  • Byte 1-2: throttle PWM (uint16_t, little endian), the actual PWM value being sent to the ESC for throttle (1000-2000)
  • Byte 3-4: steering PWM (uint16_t, little endian), the actual PWM value being sent to the servo for steering (1000-2000)
  • Byte 5-7: reserved / future use
• ID = 0x102 - E_Comms heartbeat (RX)
  • Byte 0: E_Comms heartbeat counter (uint8_t)
  • Byte 1-7: reserved / future use
• ID = CAN_VESC_MSG_NUM_TO_EXT_ID(3 = CAN_VESC_SET_RPM_MSG_NUM) (ext id) - VESC set (E)RPM (TX)
  • Byte 0-3: desired VESC ERPM (BE)
  • Byte 4-7: reserved
• ID = CAN_VESC_MSG_NUM_TO_EXT_ID(9 = CAN_VESC_STATUS_1_MSG_NUM) (ext id) - VESC status 1 (RX)
  • Byte 0-3: VESC ERPM (BE)
  • Byte 4-5: VESC current (in 0.1A, so 100 = 10A) (BE)
  • Byte 6-7: VESC duty cycle (in 0.001, so 1000 = 100%) (BE)

Note: CAN_VESC_ID is set to 7.

RC configuration

• Throttle
  • Channel: 2 (index 1)
  • At idle (center position): 1500 microseconds pulse width
  • At full throttle forward: 2000 microseconds pulse width
  • At full throttle reverse: 1000 microseconds pulse width
• Steering
  • Channel: 4 (index 3)
  • At center position: 1500 microseconds pulse width
  • At full right: 2000 microseconds pulse width
  • At full left: 1000 microseconds pulse width
• Mode switch (3 position switch)
  • Channel: 5 (index 4)
  • In RC mode: 1000 microseconds pulse width (not activated posistion)
  • In autonomous mode: 1500 microseconds pulse width (middle position)
  • In IDLE mode: 2000 microseconds pulse width (activated position)
• E-Stop switch
  • Channel: 6 (index 5)
  • Not pressed: 1000 microseconds pulse width (not activated position)
  • Pressed: 2000 microseconds pulse width (activated position)

Pin Definitions

• CAN Bus (CAN2):

  • RX: PB5
  • TX: PB6
  • CAN_S (Silent): PB7
    • LOW to enable transmitter
    • HIGH to disable transmitter

• VESC COMMS (UART5):

  • RX: PD2
  • TX: PC12

• RC Reciever (USART3)

  • RX: PB11
  • TX: PB10

• USB (Bootloader):

  • DM: PA11
  • DP: PA12

• STEERING OUT (PWM):

  • TIM1 (CH1/CH1N): PE9

• THROTTLE OUT (PWM):

  • TIM11 (CH1): PB9

• GPIOs:

  • CAN_S: PB7
  • Main Coil EN: PE5
  • Precharge EN: PE6
  • LED OUT: PE8

• System / Debug:

  • SWDIO: PA13
  • SWCLK: PA14
  • OSC_IN/OUT: PH0 / PH1 (8MHz HSE)