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a focus on LoRa and tiny pins Wednesday, June 26 2024
I took a recreational 150mg dose of pseudoephedrine this morning to help me crank through a project that had gotten the best of me in the past: figuring out enough LoRa technology to at least get to where I can visualize how to implement a LoRa-GPS tracker to put on a dog. In the past I'd only ever managed to get two Heltec devices (these happened to have displays as well as LoRa technology) to work, though they'd worked pretty well, successfully transmitting small amounts of text the half mile length of the Farm Road. The data I want to be transmitting is latitude and longitude values from a small GPS unit. I have such units, and I even have several devices that combines LoRa with GPS, though I'd never managed to get them to work.
Today I initially focused on a pair of ESP32-powered LoRa boards. There was no documentation on them whatsoever, and they didn't even have markings on them that I could Google. I was forced to find the pinout for the tiny surface-mount ESP32 processor and the pinout for the tiny surface-mount SX1278 LoRa module and then use the continuity tester function of my multimeter to see which tiny pins on one connected to tiny pins on the other. With devices this small, I had to use a magnifying glass to make sure the tip of my probe was on the correct pins, as only the roundness of the probe's tip made it possible to avoid touching more than one pin at once. Doing this, I worked out how the two devices were connected together and could use that information to tweak the code for receiving and transmitting LoRa packets. I'd then try something, it wouldn't work, and then I'd do some more testing and further refine the pin information in the code. In the process, I discovered that some of the terminals on the board had been mislabeled. I also strongly suspect that some of the pins on the ESP32 on one of the boards are shorted together by botched surface-mount soldering job. I never got either of the two boards working and eventually had to give up on them, something I was hoping I wouldn't have to do.
I did, however, finally have luck getting two of the big Lilygo TTGO TBeams communicating with each other. These are the devices with built-in GPS that I'd originally hoped to make into dog trackers, though they're a little big for that application. Strangely, though, even when the devices were all set to work on the same frequency, the TBeams and the Heltecs (those are the LoRa boards with screens that I got to work back in 2021) could not send packets to one another, and there was no obvious reason why.
At around 5:00pm, I heard our neighbor A and her boyfriend J walking with A's kid and dog Henry past our house up the Farm Road towards Georges' pool (Georges allows Gretchen and A to swim in it). Earlier today Gretchen had send me a message saying that they might drop by and have me show them my stone wall. But they never actually came down to the house, and I didn't run out to wave them over either. Meanwhile our dogs Neville and Charlotte were delighted to see them and ran up to join the party, and though Neville soon returned, Charlotte was gone long enough to suggest she'd hung out with them while they were swimming.
Gretchen was doing something after work, so I didn't have to make dinner. Instead I took a luke-warm bath (as the day had been rather hot).
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