Hi again... I became very bored with the system, so I had to make other types of verification... So I coded the microcontroller to be just a midi thru... connected the problematic yamaha piano keyboard to uC's midi in... connected my computer to uC's midi out... PC running a midi monitor and uC running this:

ORG 00H
JMP START

ORG 000BH               ;TIMER ZERO OVERFLOW
JMP TIM0

ORG 0023H
JMP SERI



START:  MOV PCON,#0
        MOV TMOD,#00100001B ;T1 8bit autoreload/T0 16bit
        MOV TL1,#255        ;Set load/reload
        MOV TH1,#255        ;
        MOV TL0,#0
        MOV TH0,#0
        SETB TR1
        SETB TR0
        MOV SCON,#01010010B
        
        MOV P2,#0
        
        SETB EA
        SETB ES
     



RUN:
        JMP RUN




SERI:
        JB TI,MIDIEnd
        CPL P0.1
        MOV A,SBUF
        MOV SBUF,A
        
Midiend:
        CLR TI
        CLR RI
        
        RETI



TIM0:
        RETI

END

 

The computer was receiving normal the real time commands from keyboard... but when I press the keys it becames very estrange... notes arrives changed and changed channels, also velocity, sometimes arrives as pitchbend (keyboard dont even has a pitch bend), aftertouch, channel pressure... (crazy?)

Keyboard connected directly to the computer works normally... also I'm shure there's no phisical problem between PC and uC.