Extend Your Pi - Raspberry Pi Hacks - page 310

writeCommand(Y);
for(i=0;i < dat;i++){
writeData(ptr[i]);
}
}
void writeCommand(int CMD){
int H_data,L_data;
H_data = CMD;
H_data &= 0xf0;
L_data = CMD;
L_data &= 0x0f;
L_data <<= 4;
writeByte(0xf8);
writeByte(H_data);
writeByte(L_data);
}
void writeData(int CMD){
int H_data,L_data;
H_data = CMD;
H_data &= 0xf0;
L_data = CMD;
L_data &= 0x0f;
L_data <<= 4;
writeByte(0xfa);
writeByte(H_data);
writeByte(L_data);
}
void writeByte(int dat){
digitalWrite(latchPin, HIGH);
delayMicroseconds(80);
SPI.transfer(dat);
digitalWrite(latchPin, LOW);
}
void clear(){
writeCommand(0x30);
writeCommand(0x01);
}