在使用LPC1768的过程中，系统已经正常跑起来了，UART也可以工作。但是在启用SSP0做SPI主站时，发现初始化后，运行，片先信号也不变低，时针也没有信号输出。MOSI也没有波形。会是设置问题吗？- void SPI_Init (void)
- {
- /* Enable SSPI0 block */
- LPC_SC->PCONP |= (1 << 21);
-
- // /* Set SSEL0 as GPIO, output high */
- // LPC_PINCON->PINSEL1 &= ~(3 << 0); /* Configure P0.16(SSEL) as GPIO */
- // LPC_GPIO0->FIODIR |= (1 << 16); /* set P0.16 as output */
- //
- // /* Configure other SSP pins: SCK, MISO, MOSI */
- // LPC_PINCON->PINSEL0 &= ~(3UL << 30);
- // LPC_PINCON->PINSEL0 |= (2UL << 30); /* P0.15: SCK0 */
- // LPC_PINCON->PINSEL1 &= ~((3<<2) | (3<<4));
- // LPC_PINCON->PINSEL1 |= ((2<<2) | (2<<4)); /* P0.17: MISO0, P0.18: MOSI0 */
-
- /* SSEL is GPIO, output set to high. */
- LPC_GPIO1->FIODIR |= (1<<21); /* P1.21 is output */
- LPC_GPIO1->FIOPIN |= (1<<21); /* set P1.21 high (SSEL inactiv) */
- LPC_PINCON->PINSEL3 &= ~(3<<12); /* P1.21 SSEL (used as GPIO) */
- /* SCK, MISO, MOSI are SSP pins. */
- LPC_PINCON->PINSEL3 &= ~(3UL<<8); /* P1.20 cleared */
- LPC_PINCON->PINSEL3 |= (3UL<<8); /* P1.20 SCK0 */
- LPC_PINCON->PINSEL3 &= ~((3<<14) | (3<<16)); /* P1.23, P1.24 cleared */
- LPC_PINCON->PINSEL3 |= ((3<<14) | (3<<16)); /* P1.23 MISO0, P1.24 MOSI0 */
-
- /* Configure SSP0_PCLK to CCLK(100MHz), default value is CCLK/4 */
- LPC_SC->PCLKSEL1 &= ~(3 << 10);
- LPC_SC->PCLKSEL1 |= (1 << 10); /* SSP0_PCLK=CCLK */
-
- /* 8bit, SPI frame format, CPOL=0, CPHA=0, SCR=0 */
- LPC_SSP0->CR0 = (0x07 << 0) | /* data width: 8bit*/
- (0x00 << 4) | /* frame format: SPI */
- (0x00 << 6) | /* CPOL: low level */
- (0x00 << 7) | /* CPHA: first edge */
- (0x00 << 8); /* SCR = 0 */
- /* Enable SSP0 as a master */
- LPC_SSP0->CR1 = (0x00 << 0) | /* Normal mode */
- (0x01 << 1) | /* Enable SSP0 */
- (0x00 << 2) | /* Master */
- (0x00 << 3); /* slave output disabled */
- /* Configure SSP0 clock rate to 400kHz (100MHz/250) */
- SPI_ConfigClockRate (SPI_CLOCKRATE_LOW);
- /* Set SSEL to high */
- SPI_CS_High ();
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