求助msp430 spi问题

qiquanwei225017 2009-9-29 10:31 楼主

串口通讯问题
我使用ADS7886做模数转换，但结果总死在第一个 while(!(IFG2 & UCA0RXIFG))这里了。。
麻烦哪位高手帮下忙，万分感谢！！！

void init_spi()
{
P3DIR |=0X41;
P3SEL |=0X21;
UCA0CTL0 |=UCMSB+UCMST+UCSYNC;//3线８位spi
UCA0CTL1 |=UCSSEL_2;
UCA0BR0 |=0X02;
UCA0BR1 |=0X00;//通讯速率smclk/2 1mhz
UCA0CTL1 &=~UCSWRST;//复位不允许
}

void ad_convert(uint data)
{

uchar dat1,dat2;
setcs;
//_NOP();
clrcs;
//_NOP();
IFG2 &= ~UCA0RXIFG;
UCA0TXBUF =0X00;//写无用值启动spi
while(!(IFG2 & UCA0RXIFG))//RXBUF准备好没？接收到数据没有？程序死在这儿！！！！！
dat1=UCA0RXBUF;//接受高字节
UCA0TXBUF =0X00;//写无用值启动spi
while(!(IFG2 & UCA0RXIFG))//RXBUF准备好没？接收到数据没有？
dat2=UCA0RXBUF;//接受低字节
data=dat1&0x000f;
data=data<<8;
data+=dat2;

}

回复评论（11）

沙发 liyiwu444

认真看下ADS7886，它的串口并不是SPI总线。
它的通讯脚包括CS/，CLK，SDO，看下数据手册的时序图，用软件实现串口的数据读取吧。

点赞 2009-9-30 12:54

板凳 reacera

用的是msp430f2618
法1：硬件spi

P3SEL |= 0x31; // P3.5,4,0 option select
UCA0CTL0 |= UCMST+UCSYNC+UCCKPL+UCMSB+UCCKPH; //3-pin, 8-bit SPI master
UCA0CTL1 |= UCSSEL_2; // SMCLK
UCA0BR0 = 0x10; // /2
UCA0BR1 = 0; //
UCA0MCTL = 0; // No modulation
UCA0CTL1 &= ~UCSWRST; // **Initialize USCI state machine**
// IE2 |= UCA0RXIE; // Ena××e USCI_A0 RX interrupt

ADS7886_CS_DIR = 1;
ADS7886_CS = 1;

unsigned int ads7886_spi_read()
{
unsigned int data = 0;

ADS7886_CS = 0;

while (!(IFG2 & UCA0TXIFG)); // USCI_B0 TX buffer ready?
UCA0TXBUF = 0x55;
while (!(IFG2 & UCA0RXIFG)); // USCI_B0 TX buffer ready?
data = UCA0RXBUF;

while (!(IFG2 & UCA0TXIFG)); // USCI_B0 TX buffer ready?
UCA0TXBUF = 0x55;
while (!(IFG2 & UCA0RXIFG)); // USCI_B0 TX buffer ready?

data = (data<<8)|UCA0RXBUF;

ADS7886_CS = 1;

return (data&0x0fff);
}

法2 ： io模拟

void ads7886_init()
{
ADS7886_SCLK_DIR = 1;
ADS7886_CS_DIR = 1;
ADS7886_SDO_DIR = 0;

ADS7886_SCLK = 1;
ADS7886_CS = 1;

}
unsigned int ads7886_read_data()
{
unsigned char i = 0;
unsigned int data = 0;
ADS7886_SCLK = 1;
ADS7886_CS = 0;

for(i=0; i<16; ++i)
{
data <<= 1;

ADS7886_SCLK = 1;

if(ADS7886_SDO)
data |= 0x0001;
else
data &= 0xfffe;

ADS7886_SCLK = 0;

}

ADS7886_SCLK = 1;
ADS7886_CS = 1;

return (data&0x0fff);
}

//第二个下降沿~第十个下降沿中间降cs置高
void ads7886_power_down()
{
unsigned char i = 0;
ADS7886_SCLK = 1;
ADS7886_CS = 0;

for(i=0; i<3; ++i)
{
ADS7886_SCLK = 0;
ADS7886_SCLK = 1;
}

ADS7886_CS = 1;

}

//A dummy cycle with CS low for more than 10 SCLK falling edges brings the device out of power down mode.
//cs拉低10个时钟周期以上
void ads7886_wake_up()
{
unsigned char i = 0;
ADS7886_SCLK = 1;
ADS7886_CS = 0;

for(i=0; i<12; ++i)
{
ADS7886_SCLK = 0;
ADS7886_SCLK = 1;
}

ADS7886_CS = 1;

}

点赞 2009-10-1 22:48