kitten playing with trackersfirst contender: nrf51822 (like almost all the boards), with an incorporated SHT30 temperature and humidity sensor, using a CR2032 battery
this one is my favorite for the moment, both because of the neat small form factor, and because the seller provides the pinout for the board... except mine doesn't match any of the ones they provide..but I asked them, see if they can provide it.
kitten playing with trackersthe second, another nrf51822, this time by itself, and this time using a CR2477 battery
this one... is not looking good. it's just too big, and that's with half the PCB empty. besides, the case has no way of attaching it to anything
it does have an upside though: I found the datasheet in the internet, with the pinout. not only that, it has 4 available digital I/O pins, which means: potential
kitten playing with trackersand the last one! this one I bought to see if anything could be done with it, but it's not an nrf51822, so I don't know if I will be able to flash it. it has a st17h65b chip
I bought it for two reasons: it's factory compatible with both Apple's FindMy network and Google's Find Hub, and it has an integrated speaker that can beep! the form factor is also very nice