Diff: SPIHalfDuplex.h

Revision:

20:029aa53d7323

Child:

27:7110ebee3484

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SPIHalfDuplex.h	Thu Jun 03 11:17:50 2010 +0000
@@ -0,0 +1,113 @@
+/* mbed Microcontroller Library - SPI
+ * Copyright (c) 2010 ARM Limited. All rights reserved.
+ * jward
+ */
+
+#ifndef MBED_SPIHALFDUPLEX_H
+#define MBED_SPIHALFDUPLEX_H
+
+#include "SPI.h"
+
+namespace mbed {
+
+/* Class: SPIHalfDuplex
+ *   A SPI half-duplex master, used for communicating with SPI slave devices
+ * over a shared data line.
+ *
+ * The default format is set to 8-bits for both master and slave, and a
+ * clock frequency of 1MHz
+ *
+ * Most SPI devies will also require Chip Select and Reset signals. These
+ * can be controlled using <DigitalOut> pins.
+ *
+ * Although this is for a shared data line, both MISO and MOSI are defined,
+ * and should be tied together externally to the mbed. This class handles
+ * the tri-stating of the MOSI pin.
+ *
+ * Example:
+ * > // Send a byte to a SPI half-duplex slave, and record the response
+ * >
+ * > #include "mbed.h"
+ * > 
+ * > SPIHalfDuplex device(p5, p6, p7) // mosi, miso, sclk
+ * >
+ * > int main() {
+ * >     int respone = device.write(0xAA);
+ * > }
+ */
+
+class SPIHalfDuplex : public SPI {
+
+public:
+    
+    /* Constructor: SPIHalfDuplex
+     *  Create a SPI half-duplex master connected to the specified pins
+     *
+     * Variables:
+     *  mosi - SPI Master Out, Slave In pin
+     *  miso - SPI Master In, Slave Out pin
+     *  sclk - SPI Clock pin
+     *  name - (optional) A string to identify the object
+     *
+     * Pin Options:
+     *  (5, 6, 7) or (11, 12, 13)
+     *
+     *  mosi or miso can be specfied as NC if not used
+     */
+    SPIHalfDuplex(PinName mosi, PinName miso, PinName sclk,
+        const char *name = NULL);
+
+#if 0 // Inherited from SPI - documentation only
+    /* Function: format
+     *  Configure the data transmission format
+     *
+     * Variables:
+     *  bits - Number of bits per SPI frame (4 - 16)
+     *  mode - Clock polarity and phase mode (0 - 3)
+     *
+     * > mode | POL PHA
+     * > -----+--------
+     * >   0  |  0   0
+     * >   1  |  0   1
+     * >   2  |  1   0
+     * >   3  |  1   1
+     */
+    void format(int bits, int mode = 0);
+
+    /* Function: frequency
+     *  Set the spi bus clock frequency
+     *
+     * Variables:
+     *  hz - SCLK frequency in hz (default = 1MHz)
+     */
+    void frequency(int hz = 1000000);
+#endif
+
+    /* Function: write
+     *  Write to the SPI Slave and return the response
+     *
+     * Variables:
+     *  value - Data to be sent to the SPI slave
+     *  returns - Response from the SPI slave
+     */
+    virtual int write(int value);
+    
+    /* Function: slave_format
+     *  Set the number of databits expected from the slave, from 4-16
+     *
+     * Variables:
+     *  sbits - Number of expected bits in the slave response
+     */
+    void slave_format(int sbits);
+
+protected:
+
+    PinName _mosi;
+    PinName _miso;
+    int     _sbits;
+
+}; // End of class
+
+} // End of namespace mbed
+
+#endif