Started looking at standalone node ideas and came across these STEM toys. Each set includes materials to build 2 units, and the community has already done a great job with porting Meshtastic support. They’re a bit pricey to buy direct, and v2.1 is redesigned to make repurposing more difficult, but I was able to pick up this pair of v2.0s off eBay for less than $40.
Stock it has a few known issues, mainly the radio. OOTB these cannot operate on LF, Medium Slow or faster is necessary. There is documentation in the GitHub discussion to make LF operation possible, but my area is switching to MF in a week so I’m just going to not worry about that for now.
It also operates using 3 AAAs, with a USBC port that can provide power but only during programming only be used for programming. It cannot supply charge to whatever batteries are used, but it can be done. Unfortunately, even with the screen off the batteries drain +40% overnight. So to avoid changing batteries every other day, I’ll be adding some pieces to it. I plan to add a 1200mAh LiPo battery and a LiPo Amigo Pro from PiShop to supply power. This could definitely be done a few different ways but I wanted to keep things clean and simple with jtag.
Using the GitHub discussion for this device, I’m also going to look at adding a GPS unit through the 4 header pins on the right side. For ease, I’m planning to attach a ublox M10 with the pigtail crimped for a 4 pin DuPont connector. Apparently these have no power mgmt for GPS, so it’ll be always on. With this approach I figure I can save battery by just unplugging the GPS when necessary.
To keep everything clean and better protected a friend and I are going to modify this case/backplate to fit the LiPo and add a hole for the USBC on the Amigo and a place for the GPS wires to feed into the battery bump for safe storage of that board.
Just got the LiPos! The excited kid in me couldn’t wait so I hooked one up to the unit I already assembled and the drain is already better. With the AAAs I could easily see a 5-10% taking the node out of sleep or communicating with another node. So far only 1% has been used after putting the node to sleep, waking it, and running a trace route to another node of mine 🙌 now that I have these I’m going to see how it drains the 74% charge the LiPo already had and start trying my hand at editing the backplate/case file.
EDIT: looks like i’ll need to get a module to boost the LiPo power up to ~5v. as-is, the board will fail to Rx/Tx and during my last test it rebooted when trying to send a test message.
Turns out the boost wasn’t necessary yet (we’ll see when the M10 GPS arrives) the devices runs fine on the LiPo alone. The Rx rebooting issue for DMs went away after I changed the RTTTL that was being used.