Using D24 for PWM on Maple Mini

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Using D24 for PWM on Maple Mini

(6 posts) (2 voices)

Started 2 years ago by jonatan.olofsson
Latest reply from ala42

jonatan.olofsson
Member

Hi,

I'm trying to get PWM working on pin D24 on my Maple Mini. In the docs, it is suggested to call USBSerial::end() before activating pwm on this pin, since it is usually occupied by the USB_DM signal. However, in my local libmaple/wirish, I have actively tried to remove all inclusion and instantiation of usb-related code, so SerialUSB is never initialized. Since it still doesn't work, i figure i have missed one of the following;

1) Some part of usb is still being configured, grabbing control over the D24 pin.
2) The initial setup for D24 differs due to its default use, so it isn't initialized as it's sibling gpio/pwm ports.

I relly would appreciate any pointers to where to look!

Best regards,
Jonatan

Posted 2 years ago #
ala42
Member

Did you also disable setupUSB() ?

Posted 2 years ago #
jonatan.olofsson
Member

Both the libmaple/usb or wirish/usb_serial.cpp are commented out in the Makefile and rules.mk respectively, and BOARD_HAVE_USB and STM32_HAVE_USB are set to false. Also, USB_DM and USB_DP have been removed from the maple_mini/board.cpp (and 24 added to the PWM list in the same file). Also BOARD_USB_* in board/board.h have been commented out.

Posted 2 years ago #
ala42
Member

Try if you can access the pin when using a modified bootloader that uses no USB. Well, you should be able to flash using a different method...

Posted 2 years ago #
jonatan.olofsson
Member

It seems to me that the bootloader should not affect the availability of the pin once the elf has been started..

I had an idea that the pc may pull DM low, but I have the same results with the usb fully disconnected..

Still out of ideas on this though.. Have anyone used D24 for PWM previously, using e.g. USBSerial.end()?

Posted 2 years ago #
ala42
Member

>It seems to me that the bootloader should not affect the availability of the pin once the elf has been started..
'Seem' and 'should' do not solve problems. The bootloader initializes USB and if it is not correctly shut down it still blocks the port.
I can use PA11 on my FreeFlight board as PWM driven motor output, do not use a boot loader and do not touch USB at all. I have no special code to use PA11 as usual port.

Posted 2 years ago #

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