Recoil Documentation

Initialization

We have a bunch of stuff to initialize. The most important aspect is the sequence of these initializations ---- there are some dependencies, and violating them creates a very serious safety hazard.

0.

For a new chip, we need to set up Flash option bytes first. This is marked by the FIRST_TIME_BOOTUP macro flag.

When the flag is set, we run the APP_initFlashOption() function, which sets the boot method to boot from Flash.

After setting up, we set the LED to indicate the operation is finished, and then halt into an infinite loop to wait for firmware reflash.

1.

Otherwise, we enter the normal MotorController_init() routine.

It will first set mode to MODE_ERROR with error code ERROR_INITIALIZE_ERROR. This is in case anything interrupts the initialization, then the system won't start. It will also load the CAN_ID and FIRMWARE_VERSION.

2.

Then, we initialize all the components. Here, we will use initialize all the volatile variables to appropriate values, and set non-volatile variables to some user values. The idea is that if LOAD_CONFIG_FROM_FLASH or LOAD_CALIBRATION_FROM_FLASH is set, then the flash loader will override these user values for the selected fields. Otherwise it will use these preset values.

LOAD_CALIBRATION_FROM_FLASH controls whether the controller uses the Motor.flux_angle_offset from flash.

LOAD_CONFIG_FROM_FLASH controls whether the controller uses other parameters from flash.

If any one of the flags is not set, then we also write the Flash with the most up to date settings.

3.

Then we start with initializing the CAN communication and setting up CAN filters.

CAN interrupt will be available.

The device will start to be responsive to CAN comm, and device status will be MODE_ERROR and ERROR_INITIALIZE_ERROR.

4.

Start opamp and ADC. The conversion will not start yet, because it is triggered by PowerStage timer.

6.

Start periphery timers. PowerStage timer is NOT enabled at this stage.

Because watchdog timer is started, the CAN bus communication watchdog will start ticking from here.

Watchdog timer interrupt will be available.

7.

Configure default LED state.

The LED will be constant white.

8.

Start PowerStage timer.

9.

Calibrate current sampling offset.

10.

Set mode to MODE_IDLE, and error code to ERROR_NO_ERROR. Exit initialization.

State Machine

Currently we support the following modes:

Disabled (sleep)

In this mode, the PowerStage will not be enabled (ENABLE pin pulled low for DRV835x, and PWM disabled for BESC). Only communication will be running. The motor controller will boot up in this mode. After initialization, the mode will be set to IDLE by the initialize() function.

This is a safe mode.

Note: Disabled is NOT used as a user mode for now.

Idle

PWM no output, all FETs are disabled, the motor is in floating mode.

This is a safe mode.

Damping

PWM output LOW, all lower FETs are open, the motor is in damping mode.

Calibration

This is the only blocking mode that is executed by the main routine.

Current

Closed-loop current control. User sets the desired value using iq_target and id_target

Torque

Closed-loop torque control. User sets the desired value using torque_target.

State Switching

On bootup, the controller will be in DISABLED mode (by default the variable initialized to 0, which is DISABLED; the first line of initialize() will also reset this to ensure this state).

If no error occured during initialization, the state will be changed to IDLE by the last line of initialize().

State switching is handled by the commutation loop running at 20kHz. The minimal safety requirement is that the commutation loop should always be executed in time and cannot be halted. Otherwise, the state cannot be switched correctly, risking error signal passed to PowerStage.

We chose to do this "synchronous" state switch mainly because there's a bunch of variables that need to be reset for some state switches. An alternate way is to keep track of current state and the state we are going to switch to every time we call setMode().

Update (Commutation) Routine

Communication Packet Format

uint16_t joint_id

remap from joint_id to transport_id and device_id

uint16_t function_id

uint32_t data*