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ESP32 LoRa Gateway

ESP32 with dual LoRa modules

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ESP32 with dual LoRa modules

Over the last ~3 years I've been on and off maintainer of the arduino-LoRA library which has received multiple requests to 'officially' support multiple radios. While in theory it does, I never had hardware on hand to test it. Additionally around the #Disaster Radio - LoRa Mesh project there has been some discussions of potential benefits of dual radios. One idea floated is that one radio is always assigned to network management, with it's Spreading Factor and Bandwidth settings chosen to maximize range while the other radio chooses settings on the fly (negotiated over the 'network link') to maximize data through-put for user data.

loranet2.pdf

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Adobe Portable Document Format - 66.73 kB - 07/13/2021 at 17:20

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  • Bring-up part two: The Workening (mostly)

    morgan3 days ago 2 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.

  • Assembly and Bring-up

    morgan07/13/2021 at 17:19 0 comments


    Assembly went fine, the usual problems were problems. The CP2102N requires the *perfect* amount of solder paste else it'll bridge and bubble. I never can seems to get USB connectors on the first try... but otherwise nothing too surprising. USB enumerated fine but I cannot seem to get it to flash without manual intervention. With power on, checking the EN and IO0 pins they both have 3.3V and I can watch them wiggle when trying to flash with esptool. But flashing will always fail unless I use a jumper wire to pull IO0 down. I've gone over the reset circuit, resoldering each component but I cannot seem to find anything wrong. Going to mull this over for the day and either continue debugging this one or assemble another if nothing obvious sticks out.

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