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SPIHalfDuplex.h
- Committer:
- simon
- Date:
- 2010-06-03
- Revision:
- 20:029aa53d7323
- Child:
- 27:7110ebee3484
File content as of revision 20:029aa53d7323:
/* 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