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.
21 #include "mbed_error.h"
23 static const PinMap PinMap_SPI_SCLK[] = {
36 static const PinMap PinMap_SPI_MOSI[] = {
49 static const PinMap PinMap_SPI_MISO[] = {
62 static const PinMap PinMap_SPI_SSEL[] = {
75 static inline int ssp_disable(spi_t *obj);
76 static inline int ssp_enable(spi_t *obj);
78 void spi_init(spi_t *obj, PinName mosi, PinName miso, PinName sclk, PinName ssel) {
79 // determine the SPI to use
80 SPIName spi_mosi = (SPIName)pinmap_peripheral(mosi, PinMap_SPI_MOSI);
81 SPIName spi_miso = (SPIName)pinmap_peripheral(miso, PinMap_SPI_MISO);
82 SPIName spi_sclk = (SPIName)pinmap_peripheral(sclk, PinMap_SPI_SCLK);
83 SPIName spi_ssel = (SPIName)pinmap_peripheral(ssel, PinMap_SPI_SSEL);
84 SPIName spi_data = (SPIName)pinmap_merge(spi_mosi, spi_miso);
85 SPIName spi_cntl = (SPIName)pinmap_merge(spi_sclk, spi_ssel);
86 obj->spi = (LPC_SSP_TypeDef*)pinmap_merge(spi_data, spi_cntl);
87 MBED_ASSERT((int)obj->spi != NC);
89 // enable power and clocking
90 switch ((int)obj->spi) {
91 case SPI_0: LPC_SC->PCONP |= 1 << 21; break;
92 case SPI_1: LPC_SC->PCONP |= 1 << 10; break;
93 case SPI_2: LPC_SC->PCONP |= 1 << 20; break;
96 // set default format and frequency
98 spi_format(obj, 8, 0, 0); // 8 bits, mode 0, master
100 spi_format(obj, 8, 0, 1); // 8 bits, mode 0, slave
102 spi_frequency(obj, 1000000);
104 // enable the ssp channel
107 // pin out the spi pins
108 pinmap_pinout(mosi, PinMap_SPI_MOSI);
109 pinmap_pinout(miso, PinMap_SPI_MISO);
110 pinmap_pinout(sclk, PinMap_SPI_SCLK);
112 pinmap_pinout(ssel, PinMap_SPI_SSEL);
116 void spi_free(spi_t *obj) {}
118 void spi_format(spi_t *obj, int bits, int mode, int slave) {
119 MBED_ASSERT(((bits >= 4) && (bits <= 16)) && ((mode >= 0) && (mode <= 3)));
122 int polarity = (mode & 0x2) ? 1 : 0;
123 int phase = (mode & 0x1) ? 1 : 0;
126 int DSS = bits - 1; // DSS (data select size)
127 int SPO = (polarity) ? 1 : 0; // SPO - clock out polarity
128 int SPH = (phase) ? 1 : 0; // SPH - clock out phase
130 int FRF = 0; // FRF (frame format) = SPI
131 uint32_t tmp = obj->spi->CR0;
141 tmp |= 0 << 0 // LBM - loop back mode - off
142 | ((slave) ? 1 : 0) << 2 // MS - master slave mode, 1 = slave
143 | 0 << 3; // SOD - slave output disable - na
148 void spi_frequency(spi_t *obj, int hz) {
151 uint32_t PCLK = PeripheralClock;
155 for (prescaler = 2; prescaler <= 254; prescaler += 2) {
156 int prescale_hz = PCLK / prescaler;
158 // calculate the divider
159 int divider = floor(((float)prescale_hz / (float)hz) + 0.5f);
161 // check we can support the divider
164 obj->spi->CPSR = prescaler;
167 obj->spi->CR0 &= ~(0xFFFF << 8);
168 obj->spi->CR0 |= (divider - 1) << 8;
173 error("Couldn't setup requested SPI frequency");
176 static inline int ssp_disable(spi_t *obj) {
177 return obj->spi->CR1 &= ~(1 << 1);
180 static inline int ssp_enable(spi_t *obj) {
181 return obj->spi->CR1 |= (1 << 1);
184 static inline int ssp_readable(spi_t *obj) {
185 return obj->spi->SR & (1 << 2);
188 static inline int ssp_writeable(spi_t *obj) {
189 return obj->spi->SR & (1 << 1);
192 static inline void ssp_write(spi_t *obj, int value) {
193 while (!ssp_writeable(obj));
194 obj->spi->DR = value;
197 static inline int ssp_read(spi_t *obj) {
198 while (!ssp_readable(obj));
202 static inline int ssp_busy(spi_t *obj) {
203 return (obj->spi->SR & (1 << 4)) ? (1) : (0);
206 int spi_master_write(spi_t *obj, int value) {
207 ssp_write(obj, value);
208 return ssp_read(obj);
211 int spi_slave_receive(spi_t *obj) {
212 return (ssp_readable(obj) && !ssp_busy(obj)) ? (1) : (0);
215 int spi_slave_read(spi_t *obj) {
219 void spi_slave_write(spi_t *obj, int value) {
220 while (ssp_writeable(obj) == 0) ;
221 obj->spi->DR = value;
224 int spi_busy(spi_t *obj) {
225 return ssp_busy(obj);