SPI.cpp

00001 /* mbed Microcontroller Library
00002  * Copyright (c) 2006-2013 ARM Limited
00003  *
00004  * Licensed under the Apache License, Version 2.0 (the "License");
00005  * you may not use this file except in compliance with the License.
00006  * You may obtain a copy of the License at
00007  *
00008  *     http://www.apache.org/licenses/LICENSE-2.0
00009  *
00010  * Unless required by applicable law or agreed to in writing, software
00011  * distributed under the License is distributed on an "AS IS" BASIS,
00012  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00013  * See the License for the specific language governing permissions and
00014  * limitations under the License.
00015  */
00016 #include "SPI.h"
00017 
00018 #if DEVICE_SPI
00019 
00020 namespace mbed {
00021 
00022 SPI::SPI(PinName mosi, PinName miso, PinName sclk, PinName _unused) :
00023         _spi(),
00024         _bits(8),
00025         _mode(0),
00026         _hz(1000000) {
00027     spi_init(&_spi, mosi, miso, sclk, NC);
00028     spi_format(&_spi, _bits, _mode, 0);
00029     spi_frequency(&_spi, _hz);
00030 }
00031 
00032 void SPI::format(int bits, int mode) {
00033     _bits = bits;
00034     _mode = mode;
00035     SPI::_owner = NULL; // Not that elegant, but works. rmeyer
00036     aquire();
00037 }
00038 
00039 void SPI::frequency(int hz) {
00040     _hz = hz;
00041     SPI::_owner = NULL; // Not that elegant, but works. rmeyer
00042     aquire();
00043 }
00044 
00045 SPI* SPI::_owner = NULL;
00046 
00047 // ignore the fact there are multiple physical spis, and always update if it wasnt us last
00048 void SPI::aquire() {
00049      if (_owner != this) {
00050         spi_format(&_spi, _bits, _mode, 0);
00051         spi_frequency(&_spi, _hz);
00052         _owner = this;
00053     }
00054 }
00055 
00056 int SPI::write(int value) {
00057     aquire();
00058     return spi_master_write(&_spi, value);
00059 }
00060 
00061 } // namespace mbed
00062 
00063 #endif