MCP23S17.cpp

00001 /* MCP23S17 - drive the Microchip MCP23S17 16-bit Port Extender using SPI
00002 * Copyright (c) 2010 Romilly Cocking
00003 * Released under the MIT License: http://mbed.org/license/mit
00004 *
00005 * version 0.4
00006 */
00007 
00008 #include "mbed.h"
00009 #include "MCP23S17.h"
00010 
00011 MCP23S17::MCP23S17(SPI* spi, PinName ncs, char writeOpcode) : _ncs(ncs) {
00012     _spi = spi;
00013     _writeOpcode = writeOpcode;
00014     _readOpcode = _writeOpcode | 1; // low order bit = 1 for read
00015     _init();
00016 }
00017 
00018 char MCP23S17::_read(char address) {
00019     _ncs = 0;
00020     _spi->write(_readOpcode);
00021     _spi->write(address);
00022     char result = _spi->write(0);
00023     _ncs = 1;
00024     return result;
00025 }
00026 
00027 char MCP23S17::_read(Port port, char address) {
00028     return _read(address + (char) port);
00029 }
00030 
00031 void MCP23S17::_write(char address, char data) {
00032     _ncs = 0;
00033     _spi->write(_writeOpcode);
00034     _spi->write(address);
00035     _spi->write(data);
00036     _ncs = 1;
00037 }
00038 
00039 void  MCP23S17::_write(Port port, char address, char data) {
00040     _write(address + (char) port, data);
00041 }
00042 
00043 void MCP23S17::_init() {
00044     _write(IOCON, (IOCON_BYTE_MODE | IOCON_HAEN )); // Hardware addressing on, operations toggle between A and B registers
00045 }
00046 
00047 void MCP23S17::direction(Port port, char direction) {
00048     _write(port, IODIRA, direction);
00049 }
00050 
00051 void MCP23S17::configurePullUps(Port port, char offOrOn) {
00052     _write(port, GPPUA, offOrOn);
00053 }
00054 
00055 void MCP23S17::interruptEnable(Port port, char interruptsEnabledMask) {
00056     _write(port, GPINTENA, interruptsEnabledMask);
00057 }
00058 
00059 void MCP23S17::mirrorInterrupts(bool mirror) {
00060  char iocon = _read(IOCON);
00061     if (mirror) {
00062         iocon = iocon | INTERRUPT_MIRROR_BIT;
00063     } else {
00064         iocon = iocon & ~INTERRUPT_MIRROR_BIT;
00065     }
00066     _write(IOCON, iocon);
00067 
00068 }
00069 
00070 void  MCP23S17::interruptPolarity(Polarity polarity) {
00071     char iocon = _read(IOCON);
00072     if (polarity == ACTIVE_LOW) {
00073         iocon = iocon & ~INTERRUPT_POLARITY_BIT;
00074     } else {
00075         iocon = iocon | INTERRUPT_POLARITY_BIT;
00076     }
00077     _write(IOCON, iocon);
00078 }
00079 
00080 void MCP23S17::defaultValue(Port port, char valuesToCompare) {
00081     _write(port, DEFVALA, valuesToCompare);
00082 }
00083 
00084 void MCP23S17::interruptControl(Port port, char interruptContolBits) {
00085     _write(port, INTCONA, interruptContolBits);
00086 }
00087 
00088 void MCP23S17::write(Port port, char byte) {
00089     _write(port, OLATA, byte);
00090 }
00091 
00092 char MCP23S17::read(Port port) {
00093     return _read(port, GPIOA);
00094 }
00095