SPISlave.h

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 #ifndef MBED_SPISLAVE_H
00017 #define MBED_SPISLAVE_H
00018 
00019 #include "platform.h"
00020 
00021 #if DEVICE_SPISLAVE
00022 
00023 #include "spi_api.h"
00024 
00025 namespace mbed {
00026 
00027 /** A SPI slave, used for communicating with a SPI Master device
00028  *
00029  * The default format is set to 8-bits, mode 0, and a clock frequency of 1MHz
00030  *
00031  * @Note Synchronization level: Not protected
00032  *
00033  * Example:
00034  * @code
00035  * // Reply to a SPI master as slave
00036  *
00037  * #include "mbed.h"
00038  *
00039  * SPISlave device(p5, p6, p7, p8); // mosi, miso, sclk, ssel
00040  *
00041  * int main() {
00042  *     device.reply(0x00);              // Prime SPI with first reply
00043  *     while(1) {
00044  *         if(device.receive()) {
00045  *             int v = device.read();   // Read byte from master
00046  *             v = (v + 1) % 0x100;     // Add one to it, modulo 256
00047  *             device.reply(v);         // Make this the next reply
00048  *         }
00049  *     }
00050  * }
00051  * @endcode
00052  */
00053 class SPISlave {
00054 
00055 public:
00056 
00057     /** Create a SPI slave connected to the specified pins
00058      *
00059      *  mosi or miso can be specfied as NC if not used
00060      *
00061      *  @param mosi SPI Master Out, Slave In pin
00062      *  @param miso SPI Master In, Slave Out pin
00063      *  @param sclk SPI Clock pin
00064      *  @param ssel SPI chip select pin
00065      */
00066     SPISlave(PinName mosi, PinName miso, PinName sclk, PinName ssel);
00067 
00068     /** Configure the data transmission format
00069      *
00070      *  @param bits Number of bits per SPI frame (4 - 16)
00071      *  @param mode Clock polarity and phase mode (0 - 3)
00072      *
00073      * @code
00074      * mode | POL PHA
00075      * -----+--------
00076      *   0  |  0   0
00077      *   1  |  0   1
00078      *   2  |  1   0
00079      *   3  |  1   1
00080      * @endcode
00081      */
00082     void format(int bits, int mode = 0);
00083 
00084     /** Set the spi bus clock frequency
00085      *
00086      *  @param hz SCLK frequency in hz (default = 1MHz)
00087      */
00088     void frequency(int hz = 1000000);
00089 
00090     /** Polls the SPI to see if data has been received
00091      *
00092      *  @returns
00093      *    0 if no data,
00094      *    1 otherwise
00095      */
00096     int receive(void);
00097 
00098     /** Retrieve  data from receive buffer as slave
00099      *
00100      *  @returns
00101      *    the data in the receive buffer
00102      */
00103     int read(void);
00104 
00105     /** Fill the transmission buffer with the value to be written out
00106      *  as slave on the next received message from the master.
00107      *
00108      *  @param value the data to be transmitted next
00109      */
00110     void reply(int value);
00111 
00112 protected:
00113     spi_t _spi;
00114 
00115     int _bits;
00116     int _mode;
00117     int _hz;
00118 };
00119 
00120 } // namespace mbed
00121 
00122 #endif
00123 
00124 #endif