以 vo_gpio.c 为例子, 通过 GpioReadPin(0x00), GpioReadPin(0x01), GpioReadPin(0x02), GpioReadPin(0x03) 來控制 VS1005 音量

代码如下:

#include <vo_stdio.h>
#include <audio.h>

ioresult SetMasterVolumeVS1005G(u_int16 leftHalfDB, u_int16 rightHalfDB) {
	if (*((u_int32*)(0xfffe))!=0xf22ccf6b) {
		return S_ERROR; //We are not running in VS1005G
	}
	// write to playerVolume (VS1005 internal global)
	*((u_int16*)(1431)) = (leftHalfDB << 8) | (rightHalfDB & 0xff);
	SetVolume(); //Call a ROM function that sets the DAC volume from playerVolume
	return S_OK;
}
int main(void) {
	SetMasterVolumeVS1005G(50,50); //Set master volume to -25dB

	// To test that we have updated the master volume, we 
	// now exec to MP3TEST.APP to hear music with the softer volume
	fclose(appFile);
	appFile = fopen("S:MP3TEST.APP","rb");		  
  return S_OK;
}