I wrote last year about the demise of NextThing.co, the maker of the CHIP computer inside the gruephone. I thought that meant that all future gruephones would be based on the Raspberry Pi series, mostly the Raspberry Pi 3B or 3B+.
So I was astounded to discover that you can still buy chip computers, though for double to triple the original $9 price. (I have speculated that low price was the downfall of the company.) I immediately bought 2 for about as much as I would have spent on a single Pi 3B+. I have since discovered that you can even get them on Amazon, though I suspect it’s the same company. I think they’re just selling old stock though, so when those are gone CHIPs may be scarce again. It’s an open-source design, so in theory some company could make more of them, but it doesn’t seem likely.
Don’t get me wrong, the Raspberry Pi is an amazing little computer, and for under $50. It’s got twice the RAM of the CHIP, and over 4 times the processing power, plus multiple USB ports and an ethernet jack. However, there are several things that make it less attractive for an embedded system like the gruephone. It also has a considerably higher power draw at idle, and combined with the lack of battery management on-board, makes it a bit more challenging to work with than the CHIP was. Also, when you plug the CHIP into a usb port, it not only charges the battery, but also provides a serial terminal, which is invaluable in debugging WiFi settings and such. The Pi is also relatively large as single board computers go, which is important when you’re trying to shoehorn it into a phone.
All those shortcomings are not fatal, but there are trade-offs. The larger footprint is made even larger by the (fairly flaky) GeekWorm UPS hat for battery power and management[*]. The higher idle current means that I only get around 6-8 hours of battery life using a 2500 mAh lipo for my Pi based computers, vs. about 15 hours for the CHIP. (I’ve since replaced the 2500 mAh pack with a monster 6600 mAh pack, and that makes the CHIP almost 2 days.) The bigger footprint also means that I’ve focused so far on building the chest phones, which I thought would have more room, (though that might not be the case.)
Since I will soon have 2 more CHIPs, I plan on building the multi-line phone using one of them. We’ll see how that goes. One of the downsides of the CHIP computer is that it has fewer general purpose GPIO lines. It has plenty of pins, but they’re mostly reserved for the HDMI and VGA daughter cards, and those are useless to me. There are only 8 general purpose GPIO lines vs. over 20 on the Pi. Another major downside is that the CHIP only has 4G of flash storage, and that’s soldered to the board. When that FLASH memory finally dies, I can’t just swap in a new sd card the way you can with a Pi.
[*] Though I’ve bought 4 Geekworm UPS hats, I really can’t recommend it. 3 of the 4 have broken down in some way, though at least one of those was my fault–plugged it in offset by one set of pins, which shorted the power to ground. The other two have a problem where the microcontroller that manages the charge/discharge stuff becomes wedged, so that once you start discharging it, it has to drain all the way down until the protection circuitry kicks in and turns off the battery–which that causes the charge controller to reset and then it will charge again. It doesn’t cause the Pi to reboot, so I live with it, but it’s less than ideal in many ways.