Olá Cicero!
Uma necessidade para funcionar o código apresentado é que exista no pic escolhido dois módulos internos:
1) O módulo CCP (para gerar o PWM correspondente ao som reproduzido).
2) O módulo SSP (para comunicação em alta velocidade com o SD Card, usando o protocolo SPI).
O PIC 16f628a tem módulo CCP mas não tem módulo SSP. O código já não funcionará simplesmente migrando.

Cláudio

Olá Cícero!
Muito obrigado por seu comentário. Vendo o link do colega Moty notei que ele já fornece o que você deseja. Tem versão para 16f877 e 16f690 .Estes não são já fáceis de encontrar? Quais seriam os picos mais fáceis e acessíveis na sua opinião?

Cláudio

#include

__CONFIG(LVPDIS & WDTDIS & UNPROTECT & HS);

#define CS RC0 //chip select input
#define Stop RB0 //stop pushbutton
#define Play RB1 //play PB
#define Rec RB2 //record PB
#define Pause RB3 //pause PB
#define RecLED RB5
#define errorLED RB4

unsigned long loc; //pause location

unsigned char SPI(unsigned char data) // send character over SPI
{
SSPBUF = data; // load character
while (!BF); // sent
return SSPBUF; // received character
}

char Command(unsigned char frame1, unsigned long adrs, unsigned char frame2 )
{
unsigned char i, res;
SPI(0xFF);
SPI((frame1 | 0x40) & 0x7F); //first 2 bits are 01
SPI((adrs & 0xFF000000) >> 24); //first of the 4 bytes address
SPI((adrs & 0x00FF0000) >> 16);
SPI((adrs & 0x0000FF00) >> 8);
SPI(adrs & 0x000000FF);
SPI(frame2 | 1); //CRC and last bit 1

for(i=0;i<10;i++) // wait for received character
{
res = SPI(0xFF);
if(res != 0xFF)break;
}
return res;
}

void InitSD(void)
{
unsigned char i;

for(i=0; i < 10; i++)SPI(0xFF); // min 74 clocks
CS=0; // Enabled for SPI mode

if (Command(0x00,0,0×95) !=1) errorLED = 1; // Reset SD command

while (Command(0x01,0,0xFF) !=0) {} //wait for idle state

SSPM1 = 0; // full speed 2MHz
CS = 1;
}

void WriteSD(void)
{
unsigned int r,i;
CS = 0;
ADON = 1;
RecLED = 1;

r = Command(25,loc,0xFF); //multi sector write
if(r != 0)
{
errorLED = 1;
ADON = 0;
RecLED = 0;
}
SPI(0xFF);
SPI(0xFF);
SPI(0xFF);

while(Stop && Pause)
{
SPI(0xFC); //multi sector token byte
for(i=0;i> 1);
}
SPI(0xFF); // CRC
SPI(0xFF); // CRC

if((r=SPI(0xFF) & 0x0F) == 0x05){ //data accepted = 0101
for(i=10000;i>0;i–){
if(r=SPI(0xFF)) break;
}
}
else{
errorLED = 1;
}
while(SPI(0xFF) != 0xFF); // while busy
loc += 512;
}
SPI(0xFD); //stop transfer token byte

SPI(0xFF);
SPI(0xFF);
while(SPI(0xFF) != 0xFF); // while busy

CS = 1;
ADON = 0;
RecLED = 0;
}

void ReadSD(void)
{
unsigned int i,r;
unsigned char data;
CS = 0;
r = Command(18,loc,0xFF); //read multi-sector
if(r != 0)errorLED = 1; //if command failed

while(Stop && Pause)
{
while(SPI(0xFF) != 0xFE); // wait for first byte
for(i=0;i> 1);
TMR2IF = 0;
}
SPI(0xFF); //discard of CRC
SPI(0xFF);
loc += 512;
}

Command(12,0×00,0xFF); //stop transmit
SPI(0xFF);
SPI(0xFF);
CS = 1;
}

void main(void)
{
// unsigned char Pause = 0;
// unsigned int i;
loc = 512;

// PIC I/O init
TRISC = 0b10010000; // sck rc3, sdo rc5, sdi rc4, CS rc0, rc2 CPP1.
TRISB = 0b1111; // switches
RBPU = 0; //pullup on
RecLED = 0;
errorLED = 0;

//analogue init
CCP1CON = 0B1100; //PWM mode
PR2 = 100; //20KHz
T2CON = 0B100; //prescale 1, post scale 1, timer2 on
ADCON1 = 0B11001110; // Fosc/16, ch1, ref=Vdd, right just.
ADCON0 = 0B1000000; // Fosc/16.

//SPI init
SSPCON = 0B110010; //low speed osc/64(125kHz),enabled,clock idle=H
CS = 1; // disable SD

InitSD();

while(1) {
if(!Rec) WriteSD();
if(!Play) ReadSD();
if(!Stop) loc = 512;

}
}