have model RR signaling code running on an ezSbc board but the board won't run with the a common anode LED connected to GPIO12, pin-28. Board runs fine after pulling then re-inserting LED into board
GPIO_NUM_12 is the TDI pin of a ESP32 WROOM.
The TDI pin can cause issues when the pin state change is messed with during boot and or program load.
GPIO_NUM_14 is the TMS pin and can cause similar issues.
My opinion, after looking at the pinout from post#1 that is not a very well laid out developer module.
what do you mean by messed up?
not booting. not taking a program. The TD0, TMS, TCK, and TDI pins are supposed to be allowed to change state during boot and program load as per the boot loader. If the pin state changes are messed with during boot or program load then odd things can happen.
Example putting a GPS device on GPIO_NUM_13 and GPIO_NUM12 doing program load. The GPS unit sends signals Irregardless of connection. The sending of data by the GPS changes the pin state during program load and booting. This can cause the ESP32 to not do as expected.
It's in the docs,
https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/index.html
somewhere.
these pins are connected to LEDs with the other end of the LED connected to Vcc. so these pins are pulled high when power is applied to the chip.
do they need to be held LOW during startup or could reset just be delayed?
If those things connected to those pins are removed does the board "work"?
above
I'd put in one or 2, test the board to see if it's OK. Add 2 more till the issue shoes back up and now you've got the GPIO_NUM causing the issue.
seem to work fine at home with the LEDs using USB for power. i couldn't reproduce the problem
but at the club, where it's powered off a 12V bus thru a 7805, it didn't come up until, as i said, i pulled the wire out the gpio12 pin of the solderless connector being used and re-inserted it.
seems clear to me that that pin is the cause of the problem
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