DSP28335通过MCBSP的clock stop模式（SPI协议）向AD9834写频率字

只看该作者 · 2014-4-16 15:03

本帖最后由 niuyuanhai 于 2014-4-16 15:32 编辑

感谢各位帮助，耽误大家时间了，情况是这样的：
DSP28335通过MCBSP的clock stop模式（SPI协议）向AD9834写频率字，正确的时序图应该是这样的：

但是我的时序测出来是这样子的：

第二个图：
   第一条：帧同步信号
   第二条：clk
   第三条：data

我配置的MCBSP代码如下：
      McbspbRegs.SPCR2.bit.XRST=0;       McbspbRegs.SPCR1.bit.RRST=0;
      McbspbRegs.SPCR2.bit.GRST=0;

McbspbRegs.SPCR1.bit.CLKSTP=11; //enable or diable the Clock Stop Mood McbspbRegs.PCR.bit.CLKXP=1; //set the transmit clock polarity
McbspbRegs.PCR.bit.CLKRP=1;
McbspbRegs.PCR.bit.CLKXM=1;
McbspbRegs.PCR.bit.SCLKME=0;
McbspbRegs.SRGR2.bit.CLKSM=1;
McbspbRegs.SRGR1.bit.CLKGDV = CLKGDV_VAL; // CLKG frequency = LSPCLK/(CLKGDV+1)
McbspbRegs.PCR.bit.FSXM=1;  //Transmit frame-synchronization mode
McbspbRegs.SRGR2.bit.FSGM=0; //Sample rate generator transmit frame-synchronization mode
McbspbRegs.PCR.bit.FSXP=1;  //Set the transmit frame-synchronization polarity
McbspbRegs.XCR2.bit.XDATDLY=01; //Set the Transmit Data Delay
McbspbRegs.RCR2.bit.RDATDLY=01;

McbspbRegs.XCR2.bit.XPHASE=0;  //Choose one or two Phases for the Transmit Frame
McbspbRegs.RCR2.bit.RPHASE=0;
McbspbRegs.XCR1.bit.XFRLEN1=0;
McbspbRegs.RCR1.bit.RFRLEN1=0;
McbspbRegs.XCR1.bit.XWDLEN1=2;
McbspbRegs.RCR1.bit.RWDLEN1=2;

delay_loop();
McbspbRegs.SPCR2.bit.GRST=1; // Enable the sample rate generator
clkg_delay_loop();          // Wait at least 2 CLKG cycles
McbspbRegs.SPCR2.bit.XRST=1; // Release TX from Reset
McbspbRegs.SPCR1.bit.RRST=1; // Release RX from Reset
McbspbRegs.SPCR2.bit.FRST=1; // Frame Sync Generator reset