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"
21 #include "mbed_error.h"
23 static const PinMap PinMap_SPI_SCLK[] = {
32 static const PinMap PinMap_SPI_MOSI[] = {
39 static const PinMap PinMap_SPI_MISO[] = {
46 static const PinMap PinMap_SPI_SSEL[] = {
53 static inline int ssp_disable(spi_t *obj);
54 static inline int ssp_enable(spi_t *obj);
56 void spi_init(spi_t *obj, PinName mosi, PinName miso, PinName sclk, PinName ssel) {
57 // determine the SPI to use
58 SPIName spi_mosi = (SPIName)pinmap_peripheral(mosi, PinMap_SPI_MOSI);
59 SPIName spi_miso = (SPIName)pinmap_peripheral(miso, PinMap_SPI_MISO);
60 SPIName spi_sclk = (SPIName)pinmap_peripheral(sclk, PinMap_SPI_SCLK);
61 SPIName spi_ssel = (SPIName)pinmap_peripheral(ssel, PinMap_SPI_SSEL);
62 SPIName spi_data = (SPIName)pinmap_merge(spi_mosi, spi_miso);
63 SPIName spi_cntl = (SPIName)pinmap_merge(spi_sclk, spi_ssel);
65 obj->spi = (LPC_SSPx_Type*)pinmap_merge(spi_data, spi_cntl);
66 MBED_ASSERT((int)obj->spi != NC);
68 // enable power and clocking
69 switch ((int)obj->spi) {
71 LPC_SYSCON->SYSAHBCLKCTRL |= 1 << 11;
72 LPC_SYSCON->SSP0CLKDIV = 0x01;
73 LPC_SYSCON->PRESETCTRL |= 1 << 0;
76 LPC_SYSCON->SYSAHBCLKCTRL |= 1 << 18;
77 LPC_SYSCON->SSP1CLKDIV = 0x01;
78 LPC_SYSCON->PRESETCTRL |= 1 << 2;
82 // set default format and frequency
84 spi_format(obj, 8, 0, 0); // 8 bits, mode 0, master
86 spi_format(obj, 8, 0, 1); // 8 bits, mode 0, slave
88 spi_frequency(obj, 1000000);
90 // enable the ssp channel
93 // pin out the spi pins
94 pinmap_pinout(mosi, PinMap_SPI_MOSI);
95 pinmap_pinout(miso, PinMap_SPI_MISO);
96 pinmap_pinout(sclk, PinMap_SPI_SCLK);
98 pinmap_pinout(ssel, PinMap_SPI_SSEL);
102 void spi_free(spi_t *obj) {}
104 void spi_format(spi_t *obj, int bits, int mode, int slave) {
106 MBED_ASSERT((bits >= 4 && bits <= 16) || (mode >= 0 && mode <= 3));
108 int polarity = (mode & 0x2) ? 1 : 0;
109 int phase = (mode & 0x1) ? 1 : 0;
112 int DSS = bits - 1; // DSS (data select size)
113 int SPO = (polarity) ? 1 : 0; // SPO - clock out polarity
114 int SPH = (phase) ? 1 : 0; // SPH - clock out phase
116 int FRF = 0; // FRF (frame format) = SPI
117 uint32_t tmp = obj->spi->CR0;
127 tmp |= 0 << 0 // LBM - loop back mode - off
128 | ((slave) ? 1 : 0) << 2 // MS - master slave mode, 1 = slave
129 | 0 << 3; // SOD - slave output disable - na
135 void spi_frequency(spi_t *obj, int hz) {
138 uint32_t PCLK = SystemCoreClock;
142 for (prescaler = 2; prescaler <= 254; prescaler += 2) {
143 int prescale_hz = PCLK / prescaler;
145 // calculate the divider
146 int divider = floor(((float)prescale_hz / (float)hz) + 0.5f);
148 // check we can support the divider
151 obj->spi->CPSR = prescaler;
154 obj->spi->CR0 &= ~(0xFFFF << 8);
155 obj->spi->CR0 |= (divider - 1) << 8;
160 error("Couldn't setup requested SPI frequency");
163 static inline int ssp_disable(spi_t *obj) {
164 return obj->spi->CR1 &= ~(1 << 1);
167 static inline int ssp_enable(spi_t *obj) {
168 return obj->spi->CR1 |= (1 << 1);
171 static inline int ssp_readable(spi_t *obj) {
172 return obj->spi->SR & (1 << 2);
175 static inline int ssp_writeable(spi_t *obj) {
176 return obj->spi->SR & (1 << 1);
179 static inline void ssp_write(spi_t *obj, int value) {
180 while (!ssp_writeable(obj));
181 obj->spi->DR = value;
184 static inline int ssp_read(spi_t *obj) {
185 while (!ssp_readable(obj));
189 static inline int ssp_busy(spi_t *obj) {
190 return (obj->spi->SR & (1 << 4)) ? (1) : (0);
193 int spi_master_write(spi_t *obj, int value) {
194 ssp_write(obj, value);
195 return ssp_read(obj);
198 int spi_slave_receive(spi_t *obj) {
199 return (ssp_readable(obj) && !ssp_busy(obj)) ? (1) : (0);
202 int spi_slave_read(spi_t *obj) {
206 void spi_slave_write(spi_t *obj, int value) {
207 while (ssp_writeable(obj) == 0) ;
208 obj->spi->DR = value;
211 int spi_busy(spi_t *obj) {
212 return ssp_busy(obj);