mbed SDK library sources
Fork of mbed-src by
Development branch of the mbed library sources. This library is kept in synch with the latest changes from the mbed SDK and it is not guaranteed to work.
If you are looking for a stable and tested release, please import one of the official mbed library releases:
Import librarymbed
The official Mbed 2 C/C++ SDK provides the software platform and libraries to build your applications.
targets/hal/TARGET_Freescale/TARGET_K20D5M/spi_api.c
- Committer:
- mbed_official
- Date:
- 2013-12-26
- Revision:
- 68:41613245dfd7
- Child:
- 73:299c67215126
File content as of revision 68:41613245dfd7:
/* mbed Microcontroller Library * Copyright (c) 2013 ARM Limited * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #include "spi_api.h" #include <math.h> #include "cmsis.h" #include "pinmap.h" #include "error.h" static const PinMap PinMap_SPI_SCLK[] = { {PTC5, SPI_0, 2}, {PTD1, SPI_0, 2}, {NC , NC , 0} }; static const PinMap PinMap_SPI_MOSI[] = { {PTD2, SPI_0, 2}, {PTC6, SPI_0, 2}, {NC , NC , 0} }; static const PinMap PinMap_SPI_MISO[] = { {PTD3, SPI_0, 2}, {PTC7, SPI_0, 2}, {NC , NC , 0} }; static const PinMap PinMap_SPI_SSEL[] = { {PTD0, SPI_0, 2}, {PTC4, SPI_0, 2}, {NC , NC , 0} }; void spi_init(spi_t *obj, PinName mosi, PinName miso, PinName sclk, PinName ssel) { // determine the SPI to use SPIName spi_mosi = (SPIName)pinmap_peripheral(mosi, PinMap_SPI_MOSI); SPIName spi_miso = (SPIName)pinmap_peripheral(miso, PinMap_SPI_MISO); SPIName spi_sclk = (SPIName)pinmap_peripheral(sclk, PinMap_SPI_SCLK); SPIName spi_ssel = (SPIName)pinmap_peripheral(ssel, PinMap_SPI_SSEL); SPIName spi_data = (SPIName)pinmap_merge(spi_mosi, spi_miso); SPIName spi_cntl = (SPIName)pinmap_merge(spi_sclk, spi_ssel); obj->spi = (SPI_Type*)pinmap_merge(spi_data, spi_cntl); if ((int)obj->spi == NC) { error("SPI pinout mapping failed"); } SIM->SCGC5 |= (1 << 11) | (1 << 12); // PortC & D SIM->SCGC6 |= 1 << 12; // spi clocks // halted state obj->spi->MCR = SPI_MCR_HALT_MASK; // set default format and frequency if (ssel == NC) { spi_format(obj, 8, 0, 0); // 8 bits, mode 0, master } else { spi_format(obj, 8, 0, 1); // 8 bits, mode 0, slave } spi_frequency(obj, 1000000); // not halt in the debug mode obj->spi->SR |= SPI_SR_EOQF_MASK; // enable SPI obj->spi->MCR &= (~SPI_MCR_HALT_MASK); // pin out the spi pins pinmap_pinout(mosi, PinMap_SPI_MOSI); pinmap_pinout(miso, PinMap_SPI_MISO); pinmap_pinout(sclk, PinMap_SPI_SCLK); if (ssel != NC) { pinmap_pinout(ssel, PinMap_SPI_SSEL); } } void spi_free(spi_t *obj) { // [TODO] } void spi_format(spi_t *obj, int bits, int mode, int slave) { if ((bits != 8) && (bits != 16)) { error("Only 8/16 bits SPI supported"); } if ((mode < 0) || (mode > 3)) { error("SPI mode unsupported"); } uint32_t polarity = (mode & 0x2) ? 1 : 0; uint32_t phase = (mode & 0x1) ? 1 : 0; // set master/slave obj->spi->MCR &= ~SPI_MCR_MSTR_MASK; obj->spi->MCR |= ((!slave) << SPI_MCR_MSTR_SHIFT); // CTAR0 is used obj->spi->CTAR[0] &= ~(SPI_CTAR_CPHA_MASK | SPI_CTAR_CPOL_MASK); obj->spi->CTAR[0] |= (polarity << SPI_CTAR_CPOL_SHIFT) | (phase << SPI_CTAR_CPHA_SHIFT); } 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 ref_spr = 0; uint32_t ref_prescaler = 0; // bus clk uint32_t PCLK = 48000000u; uint32_t prescaler = 1; uint32_t divisor = 2; for (prescaler = 1; prescaler <= 8; prescaler++) { 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; } } } // set SPPR and SPR obj->spi->CTAR[0] = ((ref_prescaler & 0x7) << 4) | (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_readable(spi_t * obj) { return (obj->spi->SR & SPI_SR_TFFF_MASK) ? 1 : 0; } 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); // wait rx buffer full while (!spi_readable(obj)); return obj->spi->POPR; } int spi_slave_receive(spi_t *obj) { return spi_readable(obj); } int spi_slave_read(spi_t *obj) { return obj->spi->POPR; } void spi_slave_write(spi_t *obj, int value) { while (!spi_writeable(obj)); }