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M680 with aftermarket headunit

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Hi. Maybe it is useful for someone like me. 


I swapped headunit on 996 with PCM1, DSP and M680 (nokia) amplifier. Then i found out amplifier does not work without proper signal from headunit.

I made simple hardware that tells amplifier to turn on max volume. That allows to use aftermarket headunit with line out.


For hardware i used attiny85 board - digispark ( probably chinese clone as there are no proper markings on board ). It is 5V microcontroller. Amplifier expects 5v serial signal ( 9bits + 1stop bit 19200baud rate )


Full code - https://pastebin.com/N3PG4Rqe

Hex firmware for attiny85 attached.


Can be done with different mcu. Bytes to send are visible in source.


WhatsApp Image 2020-08-13 at 22.02.24 (3).jpeg

WhatsApp Image 2020-08-13 at 22.02.24 (2).jpeg


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Hello, I made a renntech account specifically to respond to this post.

I have the same issue, installed an aftermarket head unit and have an M680 amplifier. I am new to microcontrollers but am willing to give this a shot. Could you elaborate on how the microcontroller was installed?

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