I had another look at the mcu that I removed from my 2nd version of the car reversing kit and saw it had chip markings on the underside. (N.B 2 pictures shown as for some reason the light obscures one or other dependent on angle )The markings say:
However I couldn't find anything useful by googling that!
Here also are some closeups of the two footprints on the 2 different car reversing kit boards I have.
mcu footprint of first kit1 I bought
mcu footprint of second kit I bought
Here is why I think it might be a PIC12
The original MCU pinout ( based on the 8 pin footprint, but for both boards) v PIC12 footprint. I have only quickly studied the PIC12 datasheet and the pcb so data may be inaccurate!
|pin number||PCB MCU function||PIC12F function|
|Pin2||Transducer address out bit0||RA5|
|Pin4||Pulse envelope detect||RA3. T1G Timer1 (16 bit timer) gate, so could accurately capture flight time|
|Pin5||monitor power? monitor Clk?||RA2 SCL? |
|Pin6 ||monitor data IO ?||RA1 SDA? |
|Pin7||Transducer address out bit1||RA0|