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

Users » jimherd » Code » MCP23017

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@13:d57de266cf19, 2010-11-29 (annotated)

Committer:: jimherd
Date:: Mon Nov 29 12:46:43 2010 +0000
Revision:: 13:d57de266cf19
Parent:: 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	12:6d9d2b277f26	3	Modified for use on the MBED ARM platform
jimherd	0:a6a5d942b58f	4
jimherd	0:a6a5d942b58f	5	This program is free software: you can redistribute it and/or modify
jimherd	0:a6a5d942b58f	6	it under the terms of the GNU General Public License as published by
jimherd	0:a6a5d942b58f	7	the Free Software Foundation, either version 3 of the License, or
jimherd	0:a6a5d942b58f	8	(at your option) any later version.
jimherd	0:a6a5d942b58f	9
jimherd	0:a6a5d942b58f	10	This program is distributed in the hope that it will be useful,
jimherd	0:a6a5d942b58f	11	but WITHOUT ANY WARRANTY; without even the implied warranty of
jimherd	0:a6a5d942b58f	12	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
jimherd	0:a6a5d942b58f	13	GNU General Public License for more details.
jimherd	0:a6a5d942b58f	14
jimherd	0:a6a5d942b58f	15	You should have received a copy of the GNU General Public License
jimherd	0:a6a5d942b58f	16	along with this program. If not, see <http://www.gnu.org/licenses/>.
jimherd	0:a6a5d942b58f	17	*/
jimherd	4:32fd6ee97dff	18
jimherd	4:32fd6ee97dff	19	#include "MCP23017.h"
jimherd	2:2a17f52c550a	20	#include "mbed.h"
jimherd	0:a6a5d942b58f	21
jimherd	0:a6a5d942b58f	22	union {
jimherd	0:a6a5d942b58f	23	uint8_t value8[2];
jimherd	0:a6a5d942b58f	24	uint16_t value16;
jimherd	0:a6a5d942b58f	25	} tmp_data;
jimherd	0:a6a5d942b58f	26
jimherd	12:6d9d2b277f26	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	12:6d9d2b277f26	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	12:6d9d2b277f26	63	/*-----------------------------------------------------------------------------
jimherd	0:a6a5d942b58f	64	* write_bit
jimherd	0:a6a5d942b58f	65	* Write a 1/0 to a single bit of the 16-bit port
jimherd	0:a6a5d942b58f	66	*/
jimherd	0:a6a5d942b58f	67	void MCP23017::write_bit(int value, int bit_number) {
jimherd	0:a6a5d942b58f	68	if (value == 0) {
jimherd	0:a6a5d942b58f	69	shadow_GPIO &= ~(1 << bit_number);
jimherd	0:a6a5d942b58f	70	} else {
jimherd	0:a6a5d942b58f	71	shadow_GPIO \|= 1 << bit_number;
jimherd	0:a6a5d942b58f	72	}
jimherd	0:a6a5d942b58f	73	writeRegister(GPIO, (unsigned short)shadow_GPIO);
jimherd	0:a6a5d942b58f	74	}
jimherd	0:a6a5d942b58f	75
jimherd	12:6d9d2b277f26	76	/*-----------------------------------------------------------------------------
jimherd	0:a6a5d942b58f	77	* Write a combination of bits to the 16-bit port
jimherd	0:a6a5d942b58f	78	*/
jimherd	0:a6a5d942b58f	79	void MCP23017::write_mask(unsigned short data, unsigned short mask) {
jimherd	0:a6a5d942b58f	80	shadow_GPIO = (shadow_GPIO & ~mask) \| data;
jimherd	0:a6a5d942b58f	81	writeRegister(GPIO, (unsigned short)shadow_GPIO);
jimherd	0:a6a5d942b58f	82	}
jimherd	0:a6a5d942b58f	83
jimherd	12:6d9d2b277f26	84	/*-----------------------------------------------------------------------------
jimherd	0:a6a5d942b58f	85	* read_bit
jimherd	0:a6a5d942b58f	86	* Read a single bit from the 16-bit port
jimherd	0:a6a5d942b58f	87	*/
jimherd	0:a6a5d942b58f	88	int MCP23017::read_bit(int bit_number) {
jimherd	0:a6a5d942b58f	89	shadow_GPIO = readRegister(GPIO);
jimherd	0:a6a5d942b58f	90	return ((shadow_GPIO >> bit_number) & 0x0001);
jimherd	0:a6a5d942b58f	91	}
jimherd	0:a6a5d942b58f	92
jimherd	12:6d9d2b277f26	93	/*-----------------------------------------------------------------------------
jimherd	0:a6a5d942b58f	94	* read_mask
jimherd	0:a6a5d942b58f	95	*/
jimherd	0:a6a5d942b58f	96	int MCP23017::read_mask(unsigned short mask) {
jimherd	0:a6a5d942b58f	97	shadow_GPIO = readRegister(GPIO);
jimherd	0:a6a5d942b58f	98	return (shadow_GPIO & mask);
jimherd	0:a6a5d942b58f	99	}
jimherd	0:a6a5d942b58f	100
jimherd	12:6d9d2b277f26	101	/*-----------------------------------------------------------------------------
jimherd	0:a6a5d942b58f	102	* Config
jimherd	0:a6a5d942b58f	103	* set direction and pull-up registers
jimherd	0:a6a5d942b58f	104	*/
jimherd	0:a6a5d942b58f	105	void MCP23017::config(unsigned short dir_config, unsigned short pullup_config, unsigned short polarity_config) {
jimherd	0:a6a5d942b58f	106	shadow_IODIR = dir_config;
jimherd	0:a6a5d942b58f	107	writeRegister(IODIR, (unsigned short)shadow_IODIR);
jimherd	0:a6a5d942b58f	108	shadow_GPPU = pullup_config;
jimherd	0:a6a5d942b58f	109	writeRegister(GPPU, (unsigned short)shadow_GPPU);
jimherd	0:a6a5d942b58f	110	shadow_IPOL = polarity_config;
jimherd	0:a6a5d942b58f	111	writeRegister(IPOL, (unsigned short)shadow_IPOL);
jimherd	0:a6a5d942b58f	112	}
jimherd	0:a6a5d942b58f	113
jimherd	12:6d9d2b277f26	114	/*-----------------------------------------------------------------------------
jimherd	12:6d9d2b277f26	115	* writeRegister
jimherd	12:6d9d2b277f26	116	* write a byte
jimherd	12:6d9d2b277f26	117	*/
jimherd	12:6d9d2b277f26	118	void MCP23017::writeRegister(int regAddress, unsigned char data) {
jimherd	12:6d9d2b277f26	119	char buffer[2];
jimherd	12:6d9d2b277f26	120
jimherd	12:6d9d2b277f26	121	buffer[0] = regAddress;
jimherd	12:6d9d2b277f26	122	buffer[1] = data;
jimherd	12:6d9d2b277f26	123	_i2c.write(MCP23017_i2cAddress, buffer, 2);
jimherd	12:6d9d2b277f26	124	}
jimherd	12:6d9d2b277f26	125
jimherd	12:6d9d2b277f26	126	/*----------------------------------------------------------------------------
jimherd	12:6d9d2b277f26	127	* write Register
jimherd	12:6d9d2b277f26	128	* write two bytes
jimherd	12:6d9d2b277f26	129	*/
jimherd	12:6d9d2b277f26	130	void MCP23017::writeRegister(int regAddress, unsigned short data) {
jimherd	12:6d9d2b277f26	131	char buffer[3];
jimherd	12:6d9d2b277f26	132
jimherd	12:6d9d2b277f26	133	buffer[0] = regAddress;
jimherd	12:6d9d2b277f26	134	tmp_data.value16 = data;
jimherd	12:6d9d2b277f26	135	buffer[1] = tmp_data.value8[0];
jimherd	12:6d9d2b277f26	136	buffer[2] = tmp_data.value8[1];
jimherd	12:6d9d2b277f26	137
jimherd	12:6d9d2b277f26	138	_i2c.write(MCP23017_i2cAddress, buffer, 3);
jimherd	12:6d9d2b277f26	139	}
jimherd	12:6d9d2b277f26	140
jimherd	12:6d9d2b277f26	141	/*-----------------------------------------------------------------------------
jimherd	12:6d9d2b277f26	142	* readRegister
jimherd	12:6d9d2b277f26	143	*/
jimherd	12:6d9d2b277f26	144	int MCP23017::readRegister(int regAddress) {
jimherd	12:6d9d2b277f26	145	char buffer[2];
jimherd	12:6d9d2b277f26	146
jimherd	12:6d9d2b277f26	147	buffer[0] = regAddress;
jimherd	12:6d9d2b277f26	148	_i2c.write(MCP23017_i2cAddress, buffer, 1);
jimherd	12:6d9d2b277f26	149	_i2c.read(MCP23017_i2cAddress, buffer, 2);
jimherd	12:6d9d2b277f26	150
jimherd	12:6d9d2b277f26	151	return ((int)(buffer[0] + (buffer[1]<<8)));
jimherd	12:6d9d2b277f26	152	}
jimherd	12:6d9d2b277f26	153
jimherd	12:6d9d2b277f26	154	/*-----------------------------------------------------------------------------
jimherd	12:6d9d2b277f26	155	* pinMode
jimherd	12:6d9d2b277f26	156	*/
jimherd	12:6d9d2b277f26	157	void MCP23017::pinMode(int pin, int mode) {
jimherd	12:6d9d2b277f26	158	if (DIR_INPUT) {
jimherd	12:6d9d2b277f26	159	shadow_IODIR \|= 1 << pin;
jimherd	12:6d9d2b277f26	160	} else {
jimherd	12:6d9d2b277f26	161	shadow_IODIR &= ~(1 << pin);
jimherd	12:6d9d2b277f26	162	}
jimherd	12:6d9d2b277f26	163	writeRegister(IODIR, (unsigned short)shadow_IODIR);
jimherd	12:6d9d2b277f26	164	}
jimherd	12:6d9d2b277f26	165
jimherd	12:6d9d2b277f26	166	/*-----------------------------------------------------------------------------
jimherd	12:6d9d2b277f26	167	* digitalRead
jimherd	12:6d9d2b277f26	168	*/
jimherd	12:6d9d2b277f26	169	int MCP23017::digitalRead(int pin) {
jimherd	12:6d9d2b277f26	170	shadow_GPIO = readRegister(GPIO);
jimherd	12:6d9d2b277f26	171	if ( shadow_GPIO & (1 << pin)) {
jimherd	12:6d9d2b277f26	172	return 1;
jimherd	12:6d9d2b277f26	173	} else {
jimherd	12:6d9d2b277f26	174	return 0;
jimherd	12:6d9d2b277f26	175	}
jimherd	12:6d9d2b277f26	176	}
jimherd	12:6d9d2b277f26	177
jimherd	12:6d9d2b277f26	178	/*-----------------------------------------------------------------------------
jimherd	0:a6a5d942b58f	179	* digitalWrite
jimherd	0:a6a5d942b58f	180	*/
jimherd	0:a6a5d942b58f	181	void MCP23017::digitalWrite(int pin, int val) {
jimherd	0:a6a5d942b58f	182	//If this pin is an INPUT pin, a write here will
jimherd	0:a6a5d942b58f	183	//enable the internal pullup
jimherd	0:a6a5d942b58f	184	//otherwise, it will set the OUTPUT voltage
jimherd	0:a6a5d942b58f	185	//as appropriate.
jimherd	0:a6a5d942b58f	186	bool isOutput = !(shadow_IODIR & 1<<pin);
jimherd	0:a6a5d942b58f	187
jimherd	0:a6a5d942b58f	188	if (isOutput) {
jimherd	0:a6a5d942b58f	189	//This is an output pin so just write the value
jimherd	0:a6a5d942b58f	190	if (val) shadow_GPIO \|= 1 << pin;
jimherd	0:a6a5d942b58f	191	else shadow_GPIO &= ~(1 << pin);
jimherd	0:a6a5d942b58f	192	writeRegister(GPIO, (unsigned short)shadow_GPIO);
jimherd	0:a6a5d942b58f	193	} else {
jimherd	0:a6a5d942b58f	194	//This is an input pin, so we need to enable the pullup
jimherd	0:a6a5d942b58f	195	if (val) {
jimherd	0:a6a5d942b58f	196	shadow_GPPU \|= 1 << pin;
jimherd	0:a6a5d942b58f	197	} else {
jimherd	0:a6a5d942b58f	198	shadow_GPPU &= ~(1 << pin);
jimherd	0:a6a5d942b58f	199	}
jimherd	0:a6a5d942b58f	200	writeRegister(GPPU, (unsigned short)shadow_GPPU);
jimherd	0:a6a5d942b58f	201	}
jimherd	0:a6a5d942b58f	202	}
jimherd	0:a6a5d942b58f	203
jimherd	12:6d9d2b277f26	204	/*-----------------------------------------------------------------------------
jimherd	0:a6a5d942b58f	205	* digitalWordRead
jimherd	0:a6a5d942b58f	206	*/
jimherd	0:a6a5d942b58f	207	unsigned short MCP23017::digitalWordRead() {
jimherd	0:a6a5d942b58f	208	shadow_GPIO = readRegister(GPIO);
jimherd	0:a6a5d942b58f	209	return shadow_GPIO;
jimherd	0:a6a5d942b58f	210	}
jimherd	0:a6a5d942b58f	211
jimherd	12:6d9d2b277f26	212	/*-----------------------------------------------------------------------------
jimherd	0:a6a5d942b58f	213	* digitalWordWrite
jimherd	0:a6a5d942b58f	214	*/
jimherd	0:a6a5d942b58f	215	void MCP23017::digitalWordWrite(unsigned short w) {
jimherd	0:a6a5d942b58f	216	shadow_GPIO = w;
jimherd	0:a6a5d942b58f	217	writeRegister(GPIO, (unsigned short)shadow_GPIO);
jimherd	0:a6a5d942b58f	218	}
jimherd	0:a6a5d942b58f	219
jimherd	12:6d9d2b277f26	220	/*-----------------------------------------------------------------------------
jimherd	0:a6a5d942b58f	221	* inputPolarityMask
jimherd	0:a6a5d942b58f	222	*/
jimherd	0:a6a5d942b58f	223	void MCP23017::inputPolarityMask(unsigned short mask) {
jimherd	0:a6a5d942b58f	224	writeRegister(IPOL, mask);
jimherd	0:a6a5d942b58f	225	}
jimherd	0:a6a5d942b58f	226
jimherd	12:6d9d2b277f26	227	/*-----------------------------------------------------------------------------
jimherd	0:a6a5d942b58f	228	* inputoutputMask
jimherd	0:a6a5d942b58f	229	*/
jimherd	0:a6a5d942b58f	230	void MCP23017::inputOutputMask(unsigned short mask) {
jimherd	0:a6a5d942b58f	231	shadow_IODIR = mask;
jimherd	0:a6a5d942b58f	232	writeRegister(IODIR, (unsigned short)shadow_IODIR);
jimherd	0:a6a5d942b58f	233	}
jimherd	0:a6a5d942b58f	234
jimherd	12:6d9d2b277f26	235	/*-----------------------------------------------------------------------------
jimherd	0:a6a5d942b58f	236	* internalPullupMask
jimherd	0:a6a5d942b58f	237	*/
jimherd	0:a6a5d942b58f	238	void MCP23017::internalPullupMask(unsigned short mask) {
jimherd	0:a6a5d942b58f	239	shadow_GPPU = mask;
jimherd	0:a6a5d942b58f	240	writeRegister(GPPU, (unsigned short)shadow_GPPU);
jimherd	0:a6a5d942b58f	241	}
jimherd	0:a6a5d942b58f	242

Repository toolbox

Export to desktop IDE

Repository details

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

MCP23017.cpp@13:d57de266cf19, 2010-11-29 (annotated)

Who changed what in which revision?

Repository toolbox

Repository details

Important Information for this Arm website

Access Warning