So, after getting serial working on a PC, I decided to see if it would work with and Android phone, and it does, at least with one, a Motorola X4; and should work on any device that supports USB-OTG
HW AND SW:
- Phone capable of USB-OTG (On-the-go, gives a USB host mode). There are apps on the play store to test whether your phone can do USB-OTG; some phones may have to be rooted for this to work, but not the X4.
- USB-OTG adapter from Micro or USB-C male to a USB A Female socket, as needed by phone.
- Serial USB Terminal software, such as https://play.google.com/store/apps/deta ... b_terminal
- USB-Serial converter, the app above lists supported chipsets, I used a generic CP2102 device from Amazon https://www.amazon.com/gp/product/B072K3Z3TL that can do 3.3v
- Pin 1 = GND
- Pin 3 = VCC (3V3)
- Pin 4 = TXD (not strictly needed, since counter doesn't take input?)
- Pin 5 = RXD
You should see something like the following. No, it's not GeigerBot, but it'll do for my simple needs of not counting CPS and CPM manually.