Sunday, August 11, 2019

Reverse Engineering Smart Wristband LM707

Recently bought a couple of "Smart bracelets"  LM707

to try RE so that I can put my own Firmware.
They have some nice features such as:
1. Color IPS LCD 80x160
2. Accelerometer
3. Pulse sensor
4. fast CPU...
5. BLE
6. Motor

I read some of articles about this and they usually have a NRF51/52 micro with BLE.
Sometimes they have the TLRS8266 by Telink.
So I thought get one open it up, see whats inside, *RE*, profit!

Got mine, opened it up and this what I got.
That weird chip is the MCU with markings 05PUN2 and a date code, and nothing else.

I had no idea what type of micro that is (still don't).
I've RE the APK that comes with it (luckily it was not protected), the app supports different types of 
MCUs (about 49 models), some are based on TELINK MCUs there are a mentions in the code.
and something called MAXSCEND, and this is what it's based on. 
No SDK no Datasheets, not info whatsoever, I have a method of uploading Firmware over OTP
(D/L of all the firmwares from the site). but they are of unknown Architecture so no idea.
I'm stuck, if anybody has any info, write in comments.

R.