Thanks Philip and Grant

Problem is definitely not BAUD RATE. I manage to sent simple MIDI message correctly, but receive problem persists.

HERE IS WORKING MIDI OUT CODE:

#include <reg52.h>
#define uchar unsigned char

void wait(uint i)
{
while(i--);
}

void Init (void)
{
TMOD = 0x20;
TL1 = 0xff;
TH1 = 0xff;
TCON = 0x50;
SCON = 0x70;
TR1 =1;
}

void main (void)
{
Init();
while(1)
{
SBUF=0x90;
while(!TI);
TI=0;
SBUF=0x30;
while(!TI);
TI=0;
SBUF=0x64;
while(!TI);
TI=0;
wait(60000);
}
}

This code will send midi note on periodicaly ( 90h 30h 64h ) on 8051(52) derivative with 12 Mhz XTAL. TX is directly connected to MIDI IN.

HERE IS NON WORKING MIDI LOOPBACK CODE:

#include <reg52.h>
#define uchar unsigned char

void Init (void)
{
TMOD = 0x20;
TL1 = 0xff;
TH1 = 0xff;
TCON = 0x50;
SCON = 0x70;
TR1 =1;
ES=1;
EA=1;
}

void main (void)
{
Init();
while(1);
}

void serial_IT(void) interrupt 4
{
uchar echo;
if(RI)
{
echo=SBUF;
RI=0;
SBUF=echo;
while(!TI);
TI=0;
}
}

The result of this code is when midi note On message is sent from MIDIOX on midi input appears four bytes ( 00h 00h 00h FEh), and for midi Off mesage returned result is (00h 00h 00h)

this FEh byte was byte i detected with previous code, on P2 as last received byte on RX

Hardware before RX input is Optoisolator with pullup resistor, start bit is fallig edge, i can not see what is wrong.



Until some new results,
thanks for consrtuctive advices and help