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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/
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