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) : _spi(spi), _ncs(ncs) {
00012     _writeOpcode = writeOpcode;
00013     _readOpcode = _writeOpcode | 1; // low order bit = 1 for read
00014     _init();
00015 }
00016 
00017 char MCP23S17::_read(char address) {
00018     _ncs = 0;
00019     _spi.write(_readOpcode);
00020     _spi.write(address);
00021     char result = _spi.write(0);
00022     _ncs = 1;
00023     return result;
00024 }
00025 
00026 char MCP23S17::_read(Port port, char address) {
00027     return _read(address + (char) port);
00028 }
00029 
00030 void MCP23S17::_write(char address, char data) {
00031     _ncs = 0;
00032     _spi.write(_writeOpcode);
00033     _spi.write(address);
00034     _spi.write(data);
00035     _ncs = 1;
00036 }
00037 
00038 void  MCP23S17::_write(Port port, char address, char data) {
00039     _write(address + (char) port, data);
00040 }
00041 
00042 void MCP23S17::_init() {
00043     _write(IOCON, (IOCON_BYTE_MODE | IOCON_HAEN )); // Hardware addressing on, operations toggle between A and B registers
00044 }
00045 
00046 void MCP23S17::direction(Port port, char direction) {
00047     _write(port, IODIRA, direction);
00048 }
00049 
00050 void MCP23S17::configurePullUps(Port port, char offOrOn) {
00051     _write(port, GPPUA, offOrOn);
00052 }
00053 
00054 void MCP23S17::interruptEnable(Port port, char interruptsEnabledMask) {
00055     _write(port, GPINTENA, interruptsEnabledMask);
00056 }
00057 
00058 void MCP23S17::mirrorInterrupts(bool mirror) {
00059  char iocon = _read(IOCON);
00060     if (mirror) {
00061         iocon = iocon | INTERRUPT_MIRROR_BIT;
00062     } else {
00063         iocon = iocon & ~INTERRUPT_MIRROR_BIT;
00064     }
00065     _write(IOCON, iocon);
00066 
00067 }
00068 
00069 void  MCP23S17::interruptPolarity(Polarity polarity) {
00070     char iocon = _read(IOCON);
00071     if (polarity == ACTIVE_LOW) {
00072         iocon = iocon & ~INTERRUPT_POLARITY_BIT;
00073     } else {
00074         iocon = iocon | INTERRUPT_POLARITY_BIT;
00075     }
00076     _write(IOCON, iocon);
00077 }
00078 
00079 void MCP23S17::defaultValue(Port port, char valuesToCompare) {
00080     _write(port, DEFVALA, valuesToCompare);
00081 }
00082 
00083 void MCP23S17::interruptControl(Port port, char interruptContolBits) {
00084     _write(port, INTCONA, interruptContolBits);
00085 }
00086 
00087 void MCP23S17::write(Port port, char byte) {
00088     _write(port, OLATA, byte);
00089 }
00090 
00091 char MCP23S17::read(Port port) {
00092     return _read(port, GPIOAA);
00093 }
00094