MCP23017 - Basic library of routines to interface to a Micro…

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Basic library of routines to interface to a Microchip MCP23017 16-bit I/O expander using an I2C interface.

Dependents: Assignment_2_herpe Final_V1 ass2 ass2 ... more

MCP23017.cpp@9:e08c29541bc4, 2010-11-29 (annotated)

Committer:: jimherd
Date:: Mon Nov 29 11:17:30 2010 +0000
Revision:: 9:e08c29541bc4
Parent:: 8:460f7a57725d
Child:: 12:6d9d2b277f26

Who changed what in which revision?

User	Revision	Line number	New contents of line
jimherd	0:a6a5d942b58f	1	/* MCP23017 library for Arduino
jimherd	0:a6a5d942b58f	2	Copyright (C) 2009 David Pye <davidmpye@gmail.com
jimherd	0:a6a5d942b58f	3
jimherd	0:a6a5d942b58f	4	This program is free software: you can redistribute it and/or modify
jimherd	0:a6a5d942b58f	5	it under the terms of the GNU General Public License as published by
jimherd	0:a6a5d942b58f	6	the Free Software Foundation, either version 3 of the License, or
jimherd	0:a6a5d942b58f	7	(at your option) any later version.
jimherd	0:a6a5d942b58f	8
jimherd	0:a6a5d942b58f	9	This program is distributed in the hope that it will be useful,
jimherd	0:a6a5d942b58f	10	but WITHOUT ANY WARRANTY; without even the implied warranty of
jimherd	0:a6a5d942b58f	11	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
jimherd	0:a6a5d942b58f	12	GNU General Public License for more details.
jimherd	0:a6a5d942b58f	13
jimherd	0:a6a5d942b58f	14	You should have received a copy of the GNU General Public License
jimherd	0:a6a5d942b58f	15	along with this program. If not, see <http://www.gnu.org/licenses/>.
jimherd	0:a6a5d942b58f	16	*/
jimherd	4:32fd6ee97dff	17
jimherd	4:32fd6ee97dff	18	#include "MCP23017.h"
jimherd	2:2a17f52c550a	19	#include "mbed.h"
jimherd	0:a6a5d942b58f	20
jimherd	0:a6a5d942b58f	21	union {
jimherd	0:a6a5d942b58f	22	uint8_t value8[2];
jimherd	0:a6a5d942b58f	23	uint16_t value16;
jimherd	0:a6a5d942b58f	24	} tmp_data;
jimherd	0:a6a5d942b58f	25
jimherd	2:2a17f52c550a	26	// using namespace mbed;
jimherd	0:a6a5d942b58f	27	/*
jimherd	0:a6a5d942b58f	28	*
jimherd	0:a6a5d942b58f	29	*/
jimherd	0:a6a5d942b58f	30	MCP23017::MCP23017(PinName sda, PinName scl, int i2cAddress) : _i2c(sda, scl) {
jimherd	0:a6a5d942b58f	31	MCP23017_i2cAddress = i2cAddress;
jimherd	0:a6a5d942b58f	32	reset(); // initialise chip to power-on condition
jimherd	0:a6a5d942b58f	33	}
jimherd	0:a6a5d942b58f	34
jimherd	9:e08c29541bc4	35	/* -----------------------------------------------------------------------------
jimherd	0:a6a5d942b58f	36	* reset
jimherd	0:a6a5d942b58f	37	* Set configuration (IOCON) and direction(IODIR) registers to initial state
jimherd	0:a6a5d942b58f	38	*/
jimherd	0:a6a5d942b58f	39	void MCP23017::reset() {
jimherd	0:a6a5d942b58f	40	//
jimherd	0:a6a5d942b58f	41	// First make sure that the device is in BANK=0 mode
jimherd	0:a6a5d942b58f	42	//
jimherd	0:a6a5d942b58f	43	writeRegister(0x05, (unsigned char)0x00);
jimherd	0:a6a5d942b58f	44	//
jimherd	0:a6a5d942b58f	45	// set direction registers to inputs
jimherd	0:a6a5d942b58f	46	//
jimherd	0:a6a5d942b58f	47	writeRegister(IODIR, (unsigned short)0xFFFF);
jimherd	0:a6a5d942b58f	48	//
jimherd	9:e08c29541bc4	49	// set all other registers to zero (last of 10 registers is OLAT)
jimherd	0:a6a5d942b58f	50	//
jimherd	0:a6a5d942b58f	51	for (int reg_addr = 2 ; reg_addr <= OLAT ; reg_addr+=2) {
jimherd	0:a6a5d942b58f	52	writeRegister(reg_addr, (unsigned short)0x0000);
jimherd	0:a6a5d942b58f	53	}
jimherd	0:a6a5d942b58f	54	//
jimherd	0:a6a5d942b58f	55	// Set the shadow registers to power-on state
jimherd	0:a6a5d942b58f	56	//
jimherd	0:a6a5d942b58f	57	shadow_IODIR = 0xFFFF;
jimherd	0:a6a5d942b58f	58	shadow_GPIO = 0;
jimherd	0:a6a5d942b58f	59	shadow_GPPU = 0;
jimherd	0:a6a5d942b58f	60	shadow_IPOL = 0;
jimherd	0:a6a5d942b58f	61	}
jimherd	0:a6a5d942b58f	62
jimherd	9:e08c29541bc4	63	/* -----------------------------------------------------------------------------
jimherd	0:a6a5d942b58f	64	* pinMode
jimherd	0:a6a5d942b58f	65	*/
jimherd	0:a6a5d942b58f	66	void MCP23017::pinMode(int pin, int mode) {
jimherd	0:a6a5d942b58f	67	if (DIR_INPUT) {
jimherd	0:a6a5d942b58f	68	shadow_IODIR \|= 1 << pin;
jimherd	0:a6a5d942b58f	69	} else {
jimherd	0:a6a5d942b58f	70	shadow_IODIR &= ~(1 << pin);
jimherd	0:a6a5d942b58f	71	}
jimherd	0:a6a5d942b58f	72	writeRegister(IODIR, (unsigned short)shadow_IODIR);
jimherd	0:a6a5d942b58f	73	}
jimherd	0:a6a5d942b58f	74
jimherd	9:e08c29541bc4	75	/* -----------------------------------------------------------------------------
jimherd	0:a6a5d942b58f	76	* digitalRead
jimherd	0:a6a5d942b58f	77	*/
jimherd	0:a6a5d942b58f	78	int MCP23017::digitalRead(int pin) {
jimherd	0:a6a5d942b58f	79	shadow_GPIO = readRegister(GPIO);
jimherd	0:a6a5d942b58f	80	if ( shadow_GPIO & (1 << pin)) {
jimherd	0:a6a5d942b58f	81	return 1;
jimherd	0:a6a5d942b58f	82	} else {
jimherd	0:a6a5d942b58f	83	return 0;
jimherd	0:a6a5d942b58f	84	}
jimherd	0:a6a5d942b58f	85	}
jimherd	0:a6a5d942b58f	86
jimherd	9:e08c29541bc4	87	/* -----------------------------------------------------------------------------
jimherd	0:a6a5d942b58f	88	* write_bit
jimherd	0:a6a5d942b58f	89	* Write a 1/0 to a single bit of the 16-bit port
jimherd	0:a6a5d942b58f	90	*/
jimherd	0:a6a5d942b58f	91	void MCP23017::write_bit(int value, int bit_number) {
jimherd	0:a6a5d942b58f	92	if (value == 0) {
jimherd	0:a6a5d942b58f	93	shadow_GPIO &= ~(1 << bit_number);
jimherd	0:a6a5d942b58f	94	} else {
jimherd	0:a6a5d942b58f	95	shadow_GPIO \|= 1 << bit_number;
jimherd	0:a6a5d942b58f	96	}
jimherd	0:a6a5d942b58f	97	writeRegister(GPIO, (unsigned short)shadow_GPIO);
jimherd	0:a6a5d942b58f	98	}
jimherd	0:a6a5d942b58f	99
jimherd	9:e08c29541bc4	100	/* -----------------------------------------------------------------------------
jimherd	0:a6a5d942b58f	101	* Write a combination of bits to the 16-bit port
jimherd	0:a6a5d942b58f	102	*/
jimherd	0:a6a5d942b58f	103	void MCP23017::write_mask(unsigned short data, unsigned short mask) {
jimherd	0:a6a5d942b58f	104	shadow_GPIO = (shadow_GPIO & ~mask) \| data;
jimherd	0:a6a5d942b58f	105	writeRegister(GPIO, (unsigned short)shadow_GPIO);
jimherd	0:a6a5d942b58f	106	}
jimherd	0:a6a5d942b58f	107
jimherd	9:e08c29541bc4	108	/* -----------------------------------------------------------------------------
jimherd	0:a6a5d942b58f	109	* read_bit
jimherd	0:a6a5d942b58f	110	* Read a single bit from the 16-bit port
jimherd	0:a6a5d942b58f	111	*/
jimherd	0:a6a5d942b58f	112	int MCP23017::read_bit(int bit_number) {
jimherd	0:a6a5d942b58f	113	shadow_GPIO = readRegister(GPIO);
jimherd	0:a6a5d942b58f	114	return ((shadow_GPIO >> bit_number) & 0x0001);
jimherd	0:a6a5d942b58f	115	}
jimherd	0:a6a5d942b58f	116
jimherd	9:e08c29541bc4	117	/* -----------------------------------------------------------------------------
jimherd	0:a6a5d942b58f	118	* read_mask
jimherd	0:a6a5d942b58f	119	*/
jimherd	0:a6a5d942b58f	120	int MCP23017::read_mask(unsigned short mask) {
jimherd	0:a6a5d942b58f	121	shadow_GPIO = readRegister(GPIO);
jimherd	0:a6a5d942b58f	122	return (shadow_GPIO & mask);
jimherd	0:a6a5d942b58f	123	}
jimherd	0:a6a5d942b58f	124
jimherd	9:e08c29541bc4	125	/* -----------------------------------------------------------------------------
jimherd	0:a6a5d942b58f	126	* Config
jimherd	0:a6a5d942b58f	127	* set direction and pull-up registers
jimherd	0:a6a5d942b58f	128	*/
jimherd	0:a6a5d942b58f	129	void MCP23017::config(unsigned short dir_config, unsigned short pullup_config, unsigned short polarity_config) {
jimherd	0:a6a5d942b58f	130	shadow_IODIR = dir_config;
jimherd	0:a6a5d942b58f	131	writeRegister(IODIR, (unsigned short)shadow_IODIR);
jimherd	0:a6a5d942b58f	132	shadow_GPPU = pullup_config;
jimherd	0:a6a5d942b58f	133	writeRegister(GPPU, (unsigned short)shadow_GPPU);
jimherd	0:a6a5d942b58f	134	shadow_IPOL = polarity_config;
jimherd	0:a6a5d942b58f	135	writeRegister(IPOL, (unsigned short)shadow_IPOL);
jimherd	0:a6a5d942b58f	136	}
jimherd	0:a6a5d942b58f	137
jimherd	9:e08c29541bc4	138	/* -----------------------------------------------------------------------------
jimherd	0:a6a5d942b58f	139	* digitalWrite
jimherd	0:a6a5d942b58f	140	*/
jimherd	0:a6a5d942b58f	141	void MCP23017::digitalWrite(int pin, int val) {
jimherd	0:a6a5d942b58f	142	//If this pin is an INPUT pin, a write here will
jimherd	0:a6a5d942b58f	143	//enable the internal pullup
jimherd	0:a6a5d942b58f	144	//otherwise, it will set the OUTPUT voltage
jimherd	0:a6a5d942b58f	145	//as appropriate.
jimherd	0:a6a5d942b58f	146	bool isOutput = !(shadow_IODIR & 1<<pin);
jimherd	0:a6a5d942b58f	147
jimherd	0:a6a5d942b58f	148	if (isOutput) {
jimherd	0:a6a5d942b58f	149	//This is an output pin so just write the value
jimherd	0:a6a5d942b58f	150	if (val) shadow_GPIO \|= 1 << pin;
jimherd	0:a6a5d942b58f	151	else shadow_GPIO &= ~(1 << pin);
jimherd	0:a6a5d942b58f	152	writeRegister(GPIO, (unsigned short)shadow_GPIO);
jimherd	0:a6a5d942b58f	153	} else {
jimherd	0:a6a5d942b58f	154	//This is an input pin, so we need to enable the pullup
jimherd	0:a6a5d942b58f	155	if (val) {
jimherd	0:a6a5d942b58f	156	shadow_GPPU \|= 1 << pin;
jimherd	0:a6a5d942b58f	157	} else {
jimherd	0:a6a5d942b58f	158	shadow_GPPU &= ~(1 << pin);
jimherd	0:a6a5d942b58f	159	}
jimherd	0:a6a5d942b58f	160	writeRegister(GPPU, (unsigned short)shadow_GPPU);
jimherd	0:a6a5d942b58f	161	}
jimherd	0:a6a5d942b58f	162	}
jimherd	0:a6a5d942b58f	163
jimherd	9:e08c29541bc4	164	/* -----------------------------------------------------------------------------
jimherd	0:a6a5d942b58f	165	* digitalWordRead
jimherd	0:a6a5d942b58f	166	*/
jimherd	0:a6a5d942b58f	167	unsigned short MCP23017::digitalWordRead() {
jimherd	0:a6a5d942b58f	168	shadow_GPIO = readRegister(GPIO);
jimherd	0:a6a5d942b58f	169	return shadow_GPIO;
jimherd	0:a6a5d942b58f	170	}
jimherd	0:a6a5d942b58f	171
jimherd	9:e08c29541bc4	172	/* -----------------------------------------------------------------------------
jimherd	0:a6a5d942b58f	173	* digitalWordWrite
jimherd	0:a6a5d942b58f	174	*/
jimherd	0:a6a5d942b58f	175	void MCP23017::digitalWordWrite(unsigned short w) {
jimherd	0:a6a5d942b58f	176	shadow_GPIO = w;
jimherd	0:a6a5d942b58f	177	writeRegister(GPIO, (unsigned short)shadow_GPIO);
jimherd	0:a6a5d942b58f	178	}
jimherd	0:a6a5d942b58f	179
jimherd	9:e08c29541bc4	180	/* -----------------------------------------------------------------------------
jimherd	0:a6a5d942b58f	181	* inputPolarityMask
jimherd	0:a6a5d942b58f	182	*/
jimherd	0:a6a5d942b58f	183	void MCP23017::inputPolarityMask(unsigned short mask) {
jimherd	0:a6a5d942b58f	184	writeRegister(IPOL, mask);
jimherd	0:a6a5d942b58f	185	}
jimherd	0:a6a5d942b58f	186
jimherd	9:e08c29541bc4	187	/* -----------------------------------------------------------------------------
jimherd	0:a6a5d942b58f	188	* inputoutputMask
jimherd	0:a6a5d942b58f	189	*/
jimherd	0:a6a5d942b58f	190	void MCP23017::inputOutputMask(unsigned short mask) {
jimherd	0:a6a5d942b58f	191	shadow_IODIR = mask;
jimherd	0:a6a5d942b58f	192	writeRegister(IODIR, (unsigned short)shadow_IODIR);
jimherd	0:a6a5d942b58f	193	}
jimherd	0:a6a5d942b58f	194
jimherd	9:e08c29541bc4	195	/* -----------------------------------------------------------------------------
jimherd	0:a6a5d942b58f	196	* internalPullupMask
jimherd	0:a6a5d942b58f	197	*/
jimherd	0:a6a5d942b58f	198	void MCP23017::internalPullupMask(unsigned short mask) {
jimherd	0:a6a5d942b58f	199	shadow_GPPU = mask;
jimherd	0:a6a5d942b58f	200	writeRegister(GPPU, (unsigned short)shadow_GPPU);
jimherd	0:a6a5d942b58f	201	}
jimherd	0:a6a5d942b58f	202
jimherd	0:a6a5d942b58f	203	//PRIVATE
jimherd	9:e08c29541bc4	204	/* -----------------------------------------------------------------------------
jimherd	0:a6a5d942b58f	205	* writeRegister
jimherd	0:a6a5d942b58f	206	* write a byte
jimherd	0:a6a5d942b58f	207	*/
jimherd	0:a6a5d942b58f	208	void MCP23017::writeRegister(int regAddress, unsigned char data) {
jimherd	0:a6a5d942b58f	209	char buffer[2];
jimherd	0:a6a5d942b58f	210
jimherd	0:a6a5d942b58f	211	buffer[0] = regAddress;
jimherd	0:a6a5d942b58f	212	buffer[1] = data;
jimherd	0:a6a5d942b58f	213	_i2c.write(MCP23017_i2cAddress, buffer, 2);
jimherd	0:a6a5d942b58f	214	}
jimherd	0:a6a5d942b58f	215
jimherd	9:e08c29541bc4	216	/* -----------------------------------------------------------------------------
jimherd	0:a6a5d942b58f	217	* writeRegister
jimherd	0:a6a5d942b58f	218	* write two bytes
jimherd	0:a6a5d942b58f	219	*/
jimherd	0:a6a5d942b58f	220	void MCP23017::writeRegister(int regAddress, unsigned short data) {
jimherd	0:a6a5d942b58f	221	char buffer[3];
jimherd	0:a6a5d942b58f	222
jimherd	0:a6a5d942b58f	223	buffer[0] = regAddress;
jimherd	0:a6a5d942b58f	224	tmp_data.value16 = data;
jimherd	0:a6a5d942b58f	225	buffer[1] = tmp_data.value8[0];
jimherd	0:a6a5d942b58f	226	buffer[2] = tmp_data.value8[1];
jimherd	0:a6a5d942b58f	227
jimherd	0:a6a5d942b58f	228	_i2c.write(MCP23017_i2cAddress, buffer, 3);
jimherd	0:a6a5d942b58f	229	}
jimherd	0:a6a5d942b58f	230
jimherd	9:e08c29541bc4	231	/* -----------------------------------------------------------------------------
jimherd	0:a6a5d942b58f	232	* readRegister
jimherd	0:a6a5d942b58f	233	*/
jimherd	0:a6a5d942b58f	234	int MCP23017::readRegister(int regAddress) {
jimherd	0:a6a5d942b58f	235	char buffer[2];
jimherd	0:a6a5d942b58f	236
jimherd	0:a6a5d942b58f	237	buffer[0] = regAddress;
jimherd	0:a6a5d942b58f	238	_i2c.write(MCP23017_i2cAddress, buffer, 1);
jimherd	0:a6a5d942b58f	239	_i2c.read(MCP23017_i2cAddress, buffer, 2);
jimherd	0:a6a5d942b58f	240
jimherd	0:a6a5d942b58f	241	return ((int)(buffer[0] + (buffer[1]<<8)));
jimherd	0:a6a5d942b58f	242	}

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Type:	Library
Created:	28 Nov 2010
Imports:	2370
Forks:	2
Commits:	14
Dependents:	25
Dependencies:	0
Followers:	74

MCP23017.cpp@9:e08c29541bc4, 2010-11-29 (annotated)

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