搞不明白为什么是0x00000004设置和清除singal

1万 · 2016-9-9 21:48

DSP6747求助void ADTEST()
{
/* DMA configuration*/
DMAconfig();
GPIO_CLR_DATA45 = 0x00000004;//clear the sync signal
SPICONFIG();
SECR = 0x00004000; //clear the recieve event
ICR |= 0x00000001; //clear the flag
EVMOMAPL137_waitusec(1000);
GPIO_SET_DATA45 = 0x00000004;//set the sync signal high
SPI_SPIINT = 0
  | ( 1 << 16 ); //DMA enable
EESR = 0x00004000;
while((IPR & 0x0000001) == 0);//wait for the end of recieve
SECR = 0x00004000;
ICR |= 0x00000001;
GPIO_CLR_DATA45 = 0x00000004;
SW_BREAKPOINT;
}
这是AD的一个测试程序搞不明白为什么是0x00000004设置和清除singal