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/platform.h"
00020 
00021 #if DEVICE_SPISLAVE
00022 
00023 #include "hal/spi_api.h"
00024 
00025 namespace mbed {
00026 /** \addtogroup drivers */
00027 /** @{*/
00028 
00029 /** A SPI slave, used for communicating with a SPI Master device
00030  *
00031  * The default format is set to 8-bits, mode 0, and a clock frequency of 1MHz
00032  *
00033  * @Note Synchronization level: Not protected
00034  *
00035  * Example:
00036  * @code
00037  * // Reply to a SPI master as slave
00038  *
00039  * #include "mbed.h"
00040  *
00041  * SPISlave device(p5, p6, p7, p8); // mosi, miso, sclk, ssel
00042  *
00043  * int main() {
00044  *     device.reply(0x00);              // Prime SPI with first reply
00045  *     while(1) {
00046  *         if(device.receive()) {
00047  *             int v = device.read();   // Read byte from master
00048  *             v = (v + 1) % 0x100;     // Add one to it, modulo 256
00049  *             device.reply(v);         // Make this the next reply
00050  *         }
00051  *     }
00052  * }
00053  * @endcode
00054  */
00055 class SPISlave {
00056 
00057 public:
00058 
00059     /** Create a SPI slave connected to the specified pins
00060      *
00061      *  mosi or miso can be specfied as NC if not used
00062      *
00063      *  @param mosi SPI Master Out, Slave In pin
00064      *  @param miso SPI Master In, Slave Out pin
00065      *  @param sclk SPI Clock pin
00066      *  @param ssel SPI chip select pin
00067      */
00068     SPISlave(PinName mosi, PinName miso, PinName sclk, PinName ssel);
00069 
00070     /** Configure the data transmission format
00071      *
00072      *  @param bits Number of bits per SPI frame (4 - 16)
00073      *  @param mode Clock polarity and phase mode (0 - 3)
00074      *
00075      * @code
00076      * mode | POL PHA
00077      * -----+--------
00078      *   0  |  0   0
00079      *   1  |  0   1
00080      *   2  |  1   0
00081      *   3  |  1   1
00082      * @endcode
00083      */
00084     void format(int bits, int mode = 0);
00085 
00086     /** Set the spi bus clock frequency
00087      *
00088      *  @param hz SCLK frequency in hz (default = 1MHz)
00089      */
00090     void frequency(int hz = 1000000);
00091 
00092     /** Polls the SPI to see if data has been received
00093      *
00094      *  @returns
00095      *    0 if no data,
00096      *    1 otherwise
00097      */
00098     int receive(void);
00099 
00100     /** Retrieve  data from receive buffer as slave
00101      *
00102      *  @returns
00103      *    the data in the receive buffer
00104      */
00105     int read(void);
00106 
00107     /** Fill the transmission buffer with the value to be written out
00108      *  as slave on the next received message from the master.
00109      *
00110      *  @param value the data to be transmitted next
00111      */
00112     void reply(int value);
00113 
00114 protected:
00115     spi_t _spi;
00116 
00117     int _bits;
00118     int _mode;
00119     int _hz;
00120 };
00121 
00122 } // namespace mbed
00123 
00124 #endif
00125 
00126 #endif
00127 
00128 /** @}*/