I have a project i’m wanting to start and i have no idea where to begin.
I’d like to send data from a proxmark3 easy via cable to an esp32 and then from bluetooth on the esp32 to an app on android or iphone
end goal is to use a proxmark with a phone app with full functionality
where should i start and what should i research?
You’d need the esp32 to have full USB host capabilities. I’m not sure any do. You’d also need all the software to be on the esp32 and that for sure won’t work. I’d recommend using a pi0 w instead. It’s about the same size but has all the software already working.
I know it’s not what you’re looking for but if you want bypass the build check out the RDV4+BlueShark. It’s a nice bit of kit!
Yeah as @Ben_bionic mentioned, it would be easier to have the “reading device” be something like Raspberry PI or something similar where you can run a UNIX system. The rest should be trivial. But hey, if you got a lot of time on your hands, I think you should be able to connect ESP32 to Proxmark3 via USB USB Device Stack - ESP32-S2 - — ESP-IDF Programming Guide latest documentation
If you are in no rush and don’t need the Proxmark3 integration specifically, I’m working on integrating ESP32 with PN532, which should be able to do the same things as you would with Proxmark3, and I’ll be releasing this as open source. Just no ETA on that 
Did you end up succeeding in this project? Because I am looking into doing the same thing. I was thinking to solder the esp32 and the proxmark3 but unfortunately I don’t have much experience in that area.
Not yet, i have about 30 other projects on my list.
The ESP32-S3 looks like it’d work well, it has USB UART capabilities.
I’ll be picking up an ESP32-S3 hopefully on 30 June or 1 July so i might pick up this project again.
It’d likely be: pm3 usb → usb UART on ESP32-S3 → Bluetooth I/O → mobile terminal app.