Hi
My Pioneer KEH-P7800R it's tape player, and after remove cassette mechanism doesn't give any errors.

It's ugly but working

I can't attach photos

This is my "Minimum hardware MP3 Player".
ATMega162 (CPU )
VS1001k (mp3 decoder)
LM2575 (voltage regulator)
Photos:

How I can scroll text on display?

Now working .
In my project emulator is directly conected to Pioneer CPU. I must make litle change in code:
[code:1]
void send_bit_1(void)
{
   sbi(DATAOUT_DDR, DATAOUT);      // DATA_OUT pin set to output and this be = 1 on IP-Bus

   sbi(DATAOUT_PORT,DATAOUT);    // this I add

   delay1(20);   //17-23
   cbi(DATAOUT_DDR, DATAOUT);      // DATA_OUT pin set to input
   delay1(16);   //12-21
}
[/code:1]

and in send_bit_0, read_acknowledge, send_acknowledge procedures.

And I use diferent compilator: CodeVision AVR and my code looks diferent.

I don't need invert any signals.

After many problems my emulator now working. In next week I put some photos of my project it's MP3 player mounted in Pioneer KEH-P7800R head unit.

or software invert TX pin?

0 Volt without any data on RX and TX pins.
If PD4975B acknowledge transfer on TX pin is aprox. 5V 35us pulse.
This pulse is after send 0x88, 0x68, 0x00 with parity bits, it's ok.
Next emulator send 4 bit high pulse, 0 parity pulse, after this data PD4975B not ackowledge.

My Pioneer after connect power send on TX pin only 2 aprox. 5us pulses, and nothing else.
It's correct?

Hi. Sorry for my English.
I send service manual on You e-mail Vitat.

I make emulator, but I have a problem.
My Atmel procesor is connected directly to RX TX pins Pioneer PD4975B procesor.
In send_message procedure emulator send to HU:

send_start_bit();
send_byte_with_checksum(CD_ID_1,0,8);
send_byte_with_checksum(CD_ID_2,1,8);
send_byte_with_checksum(CD_ID_3,1,8);
if (read_acknowledge () == false) goto Restart_Send_Message; (acknowledge==TRUE)
send_byte_with_checksum(0xF0,0,4);
if (read_acknowledge () == false) goto Restart_Send_Message;(acknowledge==FALSE)

My program looping in this place.
Help.

I dont now why, but I can't attach this file  

See this: Pioneer KEH-P7800R service manual.

Yes, I think. But not sure.
(Sorry for my English.)

Oryginal IP-Bus driver it's HA12187FP from Hitahi.
It's used in my Pioneer KEH-P7800R.