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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
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