Cheap trackers for OpenHayStack

[sonictruth]

Hi,

I bought two cheap trackers from Ali.
The first one has a chip marked as RM1200 and pads labeled RX, TX, and GND exposed (maybe it's a serial interface).

Second is marked as ST17H65B and pads labeled as P9 P10

My question is whether any of these trackers are usable with OpenHaystack. I can't find anything about the RM1200. For the Lanze one, I found the Biemster firmware, but it's for the ST17H66. Would it work on the ST17H65B? Can I use the P9 and P10 to write the firmware? I can't find any details.

Thank you.

[fz6]

https://github.com/pix/heystack-nrf5x

Has Ali links for trackers with firmware

[Systm21]

biemster/FindMy#74

This should help you, there are experts, that have a lot of knowledge.

Somewhere i read, that the st17h65B can be flashed like the 66B.

[carloalbertogiordano]

I hit the exact same wall with an RM1200-based tag. Managed to get further though. Full writeup + tools + firmware dump here: https://github.com/carloalbertogiordano/xytag-rm1230-teardown

Short version: SWD pins are SWCLK=pad6, SWDIO=pad7, RESET on a third pad (needed a pulse before the debug port responded at all, cost me most of the time). Got a clean 512KB flash dump and CPU halt/resume working over SWD, but the actual pairing/advertising logic doesn't seem to be in that flash at all, PC sampling caught execution running from an external ROM around 0x10000000 that I never got to dump. Also turned out this specific tag needs a real Apple Find My pairing handshake (manual says to use the Apple app) rather than just broadcasting on its own, so no iPhone = dead end for me without going further into that ROM.

Stopping here for now. Repo has the pinout, wiring, tools, and full notes if anyone wants to pick it up, the SWD/halt tooling should get someone else a lot further, a lot faster, than starting from scratch.