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Bring-up part two: The Workening (mostly)

A project log for ESP32 LoRa Gateway

ESP32 with dual LoRa modules

morganmorgan 07/22/2021 at 05:152 Comments

I have got it reliably flashing now after  double checking some of the soldering. As mentioned in the last post, the CP2102N soldering has to be perfect or at best it won't work at worst it gets very hot and grumpy. From the outside the solder joints all looked good but when I hit it with hot air and pressed down I got a significant solder bubble that bridged two pads. I also swapped the transistors in the reset circuit because I wasn't confidant the bag was labeled correctly.  With those swapped and the cleaned up solder flashing worked right away, flashing at 2M baud, the fasted the ESP32 supports. While flashing did work correctly the ESP isn't resetting correctly after flashing. There could still be something wrong with the reset circuit but this reminds me of a known hardware bug in older CP2102N chips. There is a chance I accidentally grabbed, it was a random single in a bag, quite annoyingly I'm missing a couple of reels from moving at the end of last year, including the newer CP2102N.

Plugging along I verified the LoRa modules where wired up correctly and it appears to be in good shape. This is the first time I've implemented two devices on shared SPI lines and it seems to have worked out.  I'll be continuing to rewrite the esp32-lora driver to better handle multiple devices. This will mostly entail moving away from using sdkconfig to determine pin configuration and instead pass that onto the user or application to define.

Discussions

morgan wrote 07/22/2021 at 23:53 point

Found a workaround, it's annoying but less so than replugging the cable...

run `idf.py build` on it's own.

run `esptool.py .... --after no_reset`

run `idf.py monitor`

it works but I'm not unconvinced this is esptools fault.

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morgan wrote 07/22/2021 at 22:29 point

I finally found the missing parts and swapped out the CP2102N for a known good part and the post flash reset is still not working. Manually resetting the device does nothing, I still don't get output over the serial port unless I physically disconnect/reconnect the USB cable. *harumph*

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