飞思卡尔K02单片机SPI

只看该作者 · 2015-12-15 15:13

本帖最后由 jpxuchao 于 2015-12-15 15:15 编辑

我想问一下spi的引脚要不要配置上拉或者下拉，下面是我的配置程序：
      SIM_SCGC6 |= SIM_SCGC6_SPI0_MASK;
      SIM->SCGC5|=SIM_SCGC5_PORTE_MASK;
      PORTE_PCR16 |=PORT_PCR_MUX(2)|PORT_PCR_PS_MASK;
      PORTE_PCR17 |=PORT_PCR_MUX(2)|PORT_PCR_PS_MASK;
      PORTE_PCR18 |=PORT_PCR_MUX(2)|PORT_PCR_PS_MASK;
      PORTE_PCR19 |=PORT_PCR_MUX(2)|PORT_PCR_PS_MASK;

   SPI0_MCR &= ~SPI_MCR_MDIS_MASK;

      SPI0_MCR  |=SPI_MCR_MSTR_MASK
                        |SPI_MCR_CONT_SCKE_MASK
                        |SPI_MCR_CLR_TXF_MASK
                        |SPI_MCR_CLR_RXF_MASK
                        |SPI_MCR_DIS_TXF_MASK
                        |SPI_MCR_DIS_RXF_MASK
                        |SPI_MCR_HALT_MASK;


SPI0_CTAR0  &= ~SPI_CTAR_FMSZ_MASK;
SPI0_CTAR0  |= SPI_CTAR_FMSZ(7);

// SPI0_CTAR0 |= SPI_CTAR_LSBFE_MASK;  //LSB
SPI0_CTAR0 &= ~SPI_CTAR_LSBFE_MASK; //MSB

/********MODE select*********/
      SPI0_CTAR0 |= SPI_CTAR_CPOL_MASK;
//       SPI0_CTAR0 &= ~SPI_CTAR_CPOL_MASK;
      SPI0_CTAR0 |= SPI_CTAR_CPHA_MASK;
// SPI0_CTAR0 &= ~SPI_CTAR_CPHA_MASK;
SPI0->SR = 0xFFFFFFFF;

SPI0_CTAR0 |= SPI_CTAR_PBR(2)|SPI_CTAR_BR(4);
SPI0_CTAR0 |= SPI_CTAR_ASC(1)|SPI_CTAR_CSSCK(1)|SPI_CTAR_PASC(1)|SPI_CTAR_PCSSCK(1);
SPI0_SR |= SPI_SR_TXRXS_MASK;
      while(1)
      {
               SPI0_MCR &= ~SPI_MCR_HALT_MASK;
            SPI_ReadWriteByte(0xF0);
               SPI_ReadWriteByte(0xAA);
               SPI_ReadWriteByte(0x55);
               delay(5);

      }
}

当我发送数据的时候，它的结果是：
见SPI结果，帮我分析一下为什么数据拉不低。