Page Comparison

...

• DShot code converted from STM32L5 development board to STM32L4 CAN ESC adapter board STM32 project, meaning that the CAN ESC adapter board can control an ESC with DShot.

• efs-canard integrated with DShot code, so CAN ESC adapter board can receive throttle inputs from flight controller and mission planner through CAN (see video abovebelow).

Protocols

• The flight controller communicates with the ESC CAN adapter through CAN (STM32L4 does not support FDCAN).

  • this is implemented with efs-canard. The board accepts throttle values from CAN messages and calls DShot functions to control the ESC.

• The CAN ESC adapter controls the ESC over DShot.

  • implemented with memory to peripheral DMA in dshot.c

  • a complementary timer pin (e.g. TIM1 CH1N) was used for DShot output generation due to the wiring of the board. This is the same as a normal timer output except HAL_TIME_*() was replaced with HAL_TIMEx_*() function calls.

  • DShot is currently normal DShot 150 (not bidirectional).

...

• Debugging

  • printf() does not work if you are using a ST-link v2 (blue usb adapter). This is because there is no SWO output pin, and thus we cannot create a SWV.

    • As an alternative, we can use SWD by clicking the “Debug“ button in STM32CUBEIDE, which allows us to step through the code and view memory and variable values (see https://uwarg-docs.atlassian.net/wiki/x/EYADdw).

  • Error No ST-LINK with the specified serial number detected: sometimes a project is linked to a specific debugger serial number, and you can unlink it from the debug configuration menu.

• MCU Configuration

  • Timer

    • No timer/DShot output

      • See latest working commit in firmware repository for valid configurations (specifically the .ioc file). The important parameters include: ARR/CCR, counter period, DMA (direction, mode, increment address, data width, ids), timer mode, timer tree (HSE output)

    • Inverted timer output: see PWM mode 1 vs PWM mode 2

  • CAN

    • CAN interrupt not triggering

      • Make sure CAN is initialized properly (HAL_CAN_*)

      • See latest working commit in firmware repository for valid configurations (specifically the .ioc file). The important parameters include:

        • NVIC CAN interrupt, GPIO pullup, prescaler, time quanta

• Timing Issues

  • DShot output timing is off

    • The function for setting DShot throttle values needs to be called continuous in an infinite while loop, and any delay in between could affect time timing. At the time of writing, the current implementation exposes a global throttle value that gets changed whenever a CAN message is handled by the CAN interrupt. This way, the DShot function call in the continuous while look loop continues to run indefinitely.

    • There also needs to be a slight delay after calling the DShot write function each time it is called, currently the delay is set to 1000ms. Removing this delay causes unknown behavior in the DShot output.

• ArduPilot not sending CAN messages

  • See how to configure Mission Planner to control ESCs over CAN: https://uwarg-docs.atlassian.net/wiki/spaces/ZP/pages/2868346921/EFS+CAN-DShot+ESC+Adapter+Board+Firmware#Flight-Controller-Configuration-in-Mission-Planner

• Motors not spinning with correct Dshot output

  • Most DShot ESCs require a throttle value of 0 to be set for some time (e.g. 300ms) before it starts accepting non-zero throttle values. See https://brushlesswhoop.com/dshot-and-bidirectional-dshot/

...