mbed library sources
Dependents: frdm_kl05z_gpio_test
Fork of mbed-src by
Diff: targets/hal/TARGET_Freescale/TARGET_K20D5M/spi_api.c
- Revision:
- 73:299c67215126
- Parent:
- 68:41613245dfd7
- Child:
- 195:442092318da6
--- a/targets/hal/TARGET_Freescale/TARGET_K20D5M/spi_api.c Mon Jan 13 10:45:05 2014 +0000 +++ b/targets/hal/TARGET_Freescale/TARGET_K20D5M/spi_api.c Tue Jan 14 20:45:05 2014 +0000 @@ -20,6 +20,7 @@ #include "cmsis.h" #include "pinmap.h" #include "error.h" +#include "clk_freqs.h" static const PinMap PinMap_SPI_SCLK[] = { {PTC5, SPI_0, 2}, @@ -59,11 +60,12 @@ error("SPI pinout mapping failed"); } - SIM->SCGC5 |= (1 << 11) | (1 << 12); // PortC & D - SIM->SCGC6 |= 1 << 12; // spi clocks + SIM->SCGC5 |= SIM_SCGC5_PORTC_MASK | SIM_SCGC5_PORTD_MASK; + SIM->SCGC6 |= SIM_SCGC6_SPI0_MASK; // halted state - obj->spi->MCR = SPI_MCR_HALT_MASK; + obj->spi->MCR &= ~SPI_MCR_MDIS_MASK; + obj->spi->MCR |= SPI_MCR_HALT_MASK | SPI_MCR_DIS_RXF_MASK | SPI_MCR_DIS_TXF_MASK; // set default format and frequency if (ssel == NC) { @@ -111,50 +113,60 @@ obj->spi->CTAR[0] |= (polarity << SPI_CTAR_CPOL_SHIFT) | (phase << SPI_CTAR_CPHA_SHIFT); } +static const uint8_t baudrate_prescaler[] = {2,3,5,7}; +static const uint32_t baudrate_scaler[] = {2, 4, 6, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768}; +static const uint8_t delay_prescaler[] = {1, 3, 5, 7}; + void spi_frequency(spi_t *obj, int hz) { uint32_t error = 0; uint32_t p_error = 0xffffffff; uint32_t ref = 0; - uint32_t spr = 0; + uint32_t br = 0; uint32_t ref_spr = 0; uint32_t ref_prescaler = 0; // bus clk - uint32_t PCLK = 48000000u; - uint32_t prescaler = 1; + uint32_t PCLK = bus_frequency(); uint32_t divisor = 2; + uint32_t prescaler; - for (prescaler = 1; prescaler <= 8; prescaler++) { + /* TODO */ + for (uint32_t i = 0; i < 4; i++) { + prescaler = baudrate_prescaler[i]; divisor = 2; - for (spr = 0; spr <= 8; spr++, divisor *= 2) { - ref = PCLK / (prescaler*divisor); - if (ref > (uint32_t)hz) - continue; - error = hz - ref; - if (error < p_error) { - ref_spr = spr; - ref_prescaler = prescaler - 1; - p_error = error; + for (br = 0; br <= 15; br++, divisor *= 2) { + for (uint32_t dr = 0; dr < 2; dr++) { + ref = (PCLK / prescaler) * ((1U + dr) / divisor); + if (ref > (uint32_t)hz) + continue; + error = hz - ref; + if (error < p_error) { + ref_spr = br; + ref_prescaler = i; + p_error = error; + } } } } - // set SPPR and SPR - obj->spi->CTAR[0] = ((ref_prescaler & 0x7) << 4) | (ref_spr & 0xf); + // set PBR and BR + obj->spi->CTAR[0] = ((ref_prescaler & 0x3) << SPI_CTAR_PBR_SHIFT) | (ref_spr & 0xf); } -static inline int spi_writeable(spi_t * obj) { - return (obj->spi->SR & SPI_SR_TCF_MASK) ? 1 : 0; +static inline int spi_writeable(spi_t *obj) { + return (obj->spi->SR & SPI_SR_TFFF_MASK) ? 1 : 0; } -static inline int spi_readable(spi_t * obj) { - return (obj->spi->SR & SPI_SR_TFFF_MASK) ? 1 : 0; +static inline int spi_readable(spi_t *obj) { + return (obj->spi->SR & SPI_SR_RFDF_MASK) ? 0 : 1; } int spi_master_write(spi_t *obj, int value) { // wait tx buffer empty while(!spi_writeable(obj)); - obj->spi->PUSHR = SPI_PUSHR_TXDATA(value & 0xff); + obj->spi->PUSHR = SPI_PUSHR_TXDATA(value & 0xff) /*| SPI_PUSHR_EOQ_MASK*/; + + while (!obj->spi->SR & SPI_SR_TCF_MASK); // wait for transfer to be complete // wait rx buffer full while (!spi_readable(obj));