Kettler YM6723L Giro C3 computer

[tom001]

Hi
I own a Giro C3 exercise bike and I'd like read data from this device with Arduino (mostly likely ESP8266 because it's small and cheap)
Is there anybody who successfully hacked or tried to hack this device?
This version is without bluetooth module so the only option I see is the 4 pinned magical undocumented "Write" connector at the back side of the device. This connector has 4 pins which pin 1 looks like ground and pin 4 is +4V. So my guess is there's a TTL UART there.

[groundFungus]

You could buy a cheap logic analyzer to check the supposed UART pins or use an oscilloscope.

The Pulseview software (free download) that runs the logic analyzer has a UART serial decoder that might help you to find out if it is serial output and decode what it is saying.

[tom001]

I'm a newbie here. I'm trying to upload photos but my last attempt ended with "too big" error.

[tom001]

Now it works. The "Write" connector is visible at the 5th. photo. It's electrically isolated from the rest of PCB and it looks like it's connected to R5F212BC/SNFP. Datasheet is here. This MCU contains two UARTs.

R5F212BCSNFP Datasheet(PDF) - Renesas Technology Corp

[tom001]

Here's one interesting link describing communication protocol of similar device from the same manufacturer
https://www.async.fi/2012/03/kettler-ergometer-serial-protocol/

[valeri_k]

tom001:
Now it works. The "Write" connector is visible at the 5th. photo. It's electrically isolated from the rest of PCB and it looks like it's connected to R5F212BC/SNFP. Datasheet is here. This MCU contains two UARTs.
R5F212BCSNFP Datasheet(PDF) - Renesas Technology Corp

Hi, If it works can you share pinout of "Write" connector?