1 /* mbed Microcontroller Library
2 * Copyright (c) 2006-2013 ARM Limited
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
16 #include "mbed_assert.h"
24 static const PinMap PinMap_SPI_SCLK[] = {
32 static const PinMap PinMap_SPI_MOSI[] = {
45 static const PinMap PinMap_SPI_MISO[] = {
59 static const PinMap PinMap_SPI_SSEL[] = {
66 void spi_init(spi_t *obj, PinName mosi, PinName miso, PinName sclk, PinName ssel) {
67 // determine the SPI to use
68 SPIName spi_mosi = (SPIName)pinmap_peripheral(mosi, PinMap_SPI_MOSI);
69 SPIName spi_miso = (SPIName)pinmap_peripheral(miso, PinMap_SPI_MISO);
70 SPIName spi_sclk = (SPIName)pinmap_peripheral(sclk, PinMap_SPI_SCLK);
71 SPIName spi_ssel = (SPIName)pinmap_peripheral(ssel, PinMap_SPI_SSEL);
72 SPIName spi_data = (SPIName)pinmap_merge(spi_mosi, spi_miso);
73 SPIName spi_cntl = (SPIName)pinmap_merge(spi_sclk, spi_ssel);
75 obj->spi = (SPI_Type*)pinmap_merge(spi_data, spi_cntl);
76 MBED_ASSERT((int)obj->spi != NC);
78 // enable power and clocking
79 switch ((int)obj->spi) {
80 case SPI_0: SIM->SCGC5 |= 1 << 13; SIM->SCGC4 |= 1 << 22; break;
81 case SPI_1: SIM->SCGC5 |= 1 << 13; SIM->SCGC4 |= 1 << 23; break;
84 // set default format and frequency
86 spi_format(obj, 8, 0, 0); // 8 bits, mode 0, master
88 spi_format(obj, 8, 0, 1); // 8 bits, mode 0, slave
90 spi_frequency(obj, 1000000);
93 obj->spi->C1 |= SPI_C1_SPE_MASK;
94 obj->spi->C2 &= ~SPI_C2_SPIMODE_MASK; //8bit
96 // pin out the spi pins
97 pinmap_pinout(mosi, PinMap_SPI_MOSI);
98 pinmap_pinout(miso, PinMap_SPI_MISO);
99 pinmap_pinout(sclk, PinMap_SPI_SCLK);
101 pinmap_pinout(ssel, PinMap_SPI_SSEL);
105 void spi_free(spi_t *obj) {
109 void spi_format(spi_t *obj, int bits, int mode, int slave) {
110 MBED_ASSERT((bits == 8) || (bits == 16));
111 MBED_ASSERT((mode >= 0) && (mode <= 3));
113 uint8_t polarity = (mode & 0x2) ? 1 : 0;
114 uint8_t phase = (mode & 0x1) ? 1 : 0;
115 uint8_t c1_data = ((!slave) << 4) | (polarity << 3) | (phase << 2);
117 // clear MSTR, CPOL and CPHA bits
118 obj->spi->C1 &= ~(0x7 << 2);
121 obj->spi->C1 |= c1_data;
123 obj->spi->C2 &= ~SPI_C2_SPIMODE_MASK;
125 obj->spi->C2 |= SPI_C2_SPIMODE_MASK;
129 void spi_frequency(spi_t *obj, int hz) {
131 uint32_t p_error = 0xffffffff;
135 uint8_t ref_prescaler = 0;
138 uint32_t PCLK = SystemCoreClock / (((SIM->CLKDIV1 & SIM_CLKDIV1_OUTDIV4_MASK) >> SIM_CLKDIV1_OUTDIV4_SHIFT) + 1);
139 uint8_t prescaler = 1;
142 for (prescaler = 1; prescaler <= 8; prescaler++) {
144 for (spr = 0; spr <= 8; spr++, divisor *= 2) {
145 ref = PCLK / (prescaler*divisor);
146 if (ref > (uint32_t)hz)
149 if (error < p_error) {
151 ref_prescaler = prescaler - 1;
158 obj->spi->BR = ((ref_prescaler & 0x7) << 4) | (ref_spr & 0xf);
161 static inline int spi_writeable(spi_t * obj) {
162 return (obj->spi->S & SPI_S_SPTEF_MASK) ? 1 : 0;
165 static inline int spi_readable(spi_t * obj) {
166 return (obj->spi->S & SPI_S_SPRF_MASK) ? 1 : 0;
169 int spi_master_write(spi_t *obj, int value) {
171 if (obj->spi->C2 & SPI_C2_SPIMODE_MASK) {
173 while(!spi_writeable(obj));
174 obj->spi->DL = (value & 0xff);
175 obj->spi->DH = ((value >> 8) & 0xff);
177 // wait rx buffer full
178 while (!spi_readable(obj));
180 ret = (ret << 8) | obj->spi->DL;
183 while(!spi_writeable(obj));
184 obj->spi->DL = (value & 0xff);
186 // wait rx buffer full
187 while (!spi_readable(obj));
188 ret = (obj->spi->DL & 0xff);
194 int spi_slave_receive(spi_t *obj) {
195 return spi_readable(obj);
198 int spi_slave_read(spi_t *obj) {
200 if (obj->spi->C2 & SPI_C2_SPIMODE_MASK) {
202 ret = ((ret << 8) | obj->spi->DL);
209 void spi_slave_write(spi_t *obj, int value) {
210 while (!spi_writeable(obj));
211 if (obj->spi->C2 & SPI_C2_SPIMODE_MASK) {
212 obj->spi->DL = (value & 0xff);
213 obj->spi->DH = ((value >> 8) & 0xff);
215 obj->spi->DL = value;