Basic library of routines to interface to a Microchip MCP23017 16-bit I/O expander using an I2C interface.
Dependents: acd52832_beep_buzzer_ints
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Revision 0:a6a5d942b58f, committed 2010-11-28
- Comitter:
- jimherd
- Date:
- Sun Nov 28 20:41:49 2010 +0000
- Child:
- 1:d54d7002bae2
- Commit message:
Changed in this revision
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MCP23017.h | Show annotated file Show diff for this revision Revisions of this file |
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/MCP23017.cpp Sun Nov 28 20:41:49 2010 +0000 @@ -0,0 +1,243 @@ +/* MCP23017 library for Arduino + Copyright (C) 2009 David Pye <davidmpye@gmail.com + + This program is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <http://www.gnu.org/licenses/>. +*/ +#include "MCP23017.h" +#include "mbed.h" + +union { + uint8_t value8[2]; + uint16_t value16; +} tmp_data; + +using namespace mbed; +/* + * + */ +MCP23017::MCP23017(PinName sda, PinName scl, int i2cAddress) : _i2c(sda, scl) { + MCP23017_i2cAddress = i2cAddress; + reset(); // initialise chip to power-on condition +} + +/******************************************************************************* + * reset + * Set configuration (IOCON) and direction(IODIR) registers to initial state + */ +void MCP23017::reset() { +// +// First make sure that the device is in BANK=0 mode +// + writeRegister(0x05, (unsigned char)0x00); +// +// set direction registers to inputs +// + writeRegister(IODIR, (unsigned short)0xFFFF); +// +// set all other registers to zero (last od 10 registers is OLAT) +// + for (int reg_addr = 2 ; reg_addr <= OLAT ; reg_addr+=2) { + writeRegister(reg_addr, (unsigned short)0x0000); + } +// +// Set the shadow registers to power-on state +// + shadow_IODIR = 0xFFFF; + shadow_GPIO = 0; + shadow_GPPU = 0; + shadow_IPOL = 0; +} + +/******************************************************************************* + * pinMode + */ +void MCP23017::pinMode(int pin, int mode) { + if (DIR_INPUT) { + shadow_IODIR |= 1 << pin; + } else { + shadow_IODIR &= ~(1 << pin); + } + writeRegister(IODIR, (unsigned short)shadow_IODIR); +} + +/******************************************************************************* + * digitalRead + */ +int MCP23017::digitalRead(int pin) { + shadow_GPIO = readRegister(GPIO); + if ( shadow_GPIO & (1 << pin)) { + return 1; + } else { + return 0; + } +} + +/******************************************************************************* + * write_bit + * Write a 1/0 to a single bit of the 16-bit port + */ +void MCP23017::write_bit(int value, int bit_number) { + if (value == 0) { + shadow_GPIO &= ~(1 << bit_number); + } else { + shadow_GPIO |= 1 << bit_number; + } + writeRegister(GPIO, (unsigned short)shadow_GPIO); +} + +/******************************************************************************* + * Write a combination of bits to the 16-bit port + */ +void MCP23017::write_mask(unsigned short data, unsigned short mask) { + shadow_GPIO = (shadow_GPIO & ~mask) | data; + writeRegister(GPIO, (unsigned short)shadow_GPIO); +} + +/******************************************************************************* + * read_bit + * Read a single bit from the 16-bit port + */ +int MCP23017::read_bit(int bit_number) { + shadow_GPIO = readRegister(GPIO); + return ((shadow_GPIO >> bit_number) & 0x0001); +} + +/******************************************************************************* + * read_mask + */ +int MCP23017::read_mask(unsigned short mask) { + shadow_GPIO = readRegister(GPIO); + return (shadow_GPIO & mask); +} + +/******************************************************************************* + * Config + * set direction and pull-up registers + */ +void MCP23017::config(unsigned short dir_config, unsigned short pullup_config, unsigned short polarity_config) { + shadow_IODIR = dir_config; + writeRegister(IODIR, (unsigned short)shadow_IODIR); + shadow_GPPU = pullup_config; + writeRegister(GPPU, (unsigned short)shadow_GPPU); + shadow_IPOL = polarity_config; + writeRegister(IPOL, (unsigned short)shadow_IPOL); +} + +/******************************************************************************* + * digitalWrite + */ +void MCP23017::digitalWrite(int pin, int val) { + //If this pin is an INPUT pin, a write here will + //enable the internal pullup + //otherwise, it will set the OUTPUT voltage + //as appropriate. + bool isOutput = !(shadow_IODIR & 1<<pin); + + if (isOutput) { + //This is an output pin so just write the value + if (val) shadow_GPIO |= 1 << pin; + else shadow_GPIO &= ~(1 << pin); + writeRegister(GPIO, (unsigned short)shadow_GPIO); + } else { + //This is an input pin, so we need to enable the pullup + if (val) { + shadow_GPPU |= 1 << pin; + } else { + shadow_GPPU &= ~(1 << pin); + } + writeRegister(GPPU, (unsigned short)shadow_GPPU); + } +} + +/******************************************************************************* + * digitalWordRead + */ +unsigned short MCP23017::digitalWordRead() { + shadow_GPIO = readRegister(GPIO); + return shadow_GPIO; +} + +/******************************************************************************* + * digitalWordWrite + */ +void MCP23017::digitalWordWrite(unsigned short w) { + shadow_GPIO = w; + writeRegister(GPIO, (unsigned short)shadow_GPIO); +} + +/******************************************************************************* + * inputPolarityMask + */ +void MCP23017::inputPolarityMask(unsigned short mask) { + writeRegister(IPOL, mask); +} + +/******************************************************************************* + * inputoutputMask + */ +void MCP23017::inputOutputMask(unsigned short mask) { + shadow_IODIR = mask; + writeRegister(IODIR, (unsigned short)shadow_IODIR); +} + +/******************************************************************************* + * internalPullupMask + */ +void MCP23017::internalPullupMask(unsigned short mask) { + shadow_GPPU = mask; + writeRegister(GPPU, (unsigned short)shadow_GPPU); +} + + + +//PRIVATE +/******************************************************************************* + * writeRegister + * write a byte + */ +void MCP23017::writeRegister(int regAddress, unsigned char data) { + char buffer[2]; + + buffer[0] = regAddress; + buffer[1] = data; + _i2c.write(MCP23017_i2cAddress, buffer, 2); +} + +/******************************************************************************* + * writeRegister + * write two bytes + */ +void MCP23017::writeRegister(int regAddress, unsigned short data) { + char buffer[3]; + + buffer[0] = regAddress; + tmp_data.value16 = data; + buffer[1] = tmp_data.value8[0]; + buffer[2] = tmp_data.value8[1]; + + _i2c.write(MCP23017_i2cAddress, buffer, 3); +} + +/******************************************************************************* + * readRegister + */ +int MCP23017::readRegister(int regAddress) { + char buffer[2]; + + buffer[0] = regAddress; + _i2c.write(MCP23017_i2cAddress, buffer, 1); + _i2c.read(MCP23017_i2cAddress, buffer, 2); + + return ((int)(buffer[0] + (buffer[1]<<8))); +}
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/MCP23017.h Sun Nov 28 20:41:49 2010 +0000 @@ -0,0 +1,135 @@ +/* MCP23017 library for Arduino + Copyright (C) 2009 David Pye <davidmpye@gmail.com + + This program is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <http://www.gnu.org/licenses/>. +*/ + +#include "mbed.h" + +#ifndef MBED_MCP23017_H +#define MBED_MCP23017_H + +// +// Register defines from data sheet - we set IOCON.BANK to 0 +// as it is easier to manage the registers sequentially. +// +#define IODIR 0x00 +#define IPOL 0x02 +#define GPINTEN 0x04 +#define DEFVAL 0x06 +#define INTCON 0x08 +#define IOCON 0x0A +#define GPPU 0x0C +#define INTF 0x0E +#define INTCAP 0x10 +#define GPIO 0x12 +#define OLAT 0x14 + +#define I2C_BASE_ADDRESS 0x40 + +#define DIR_OUTPUT 0 +#define DIR_INPUT 1 + +class MCP23017 { +public: + /** Constructor for the MCP23017 connected to specified I2C pins at a specific address + * + * 16-bit I/O expander with I2C interface + * + * @param sda I2C data pin + * @param scl I2C clock pin + * @param i2cAddress I2C address + */ + MCP23017(PinName sda, PinName scl, int i2cAddress); + + /** Reset MCP23017 device to its power-on state + */ + void reset(void); + + /** Write a 0/1 value to an output bit + * + * @param value 0 or 1 + * @param bit_number bit number range 0 --> 15 + */ + void write_bit(int value, int bit_number); + + /** Write a 0/1 value to an output bit + * + * @param data 16-bit data value + * @param mask 16-bit mask value + */ + void write_mask(unsigned short data, unsigned short mask); + + /** Read a 0/1 value from an input bit + * + * @param bit_number bit number range 0 --> 15 + * @return 0/1 value read + */ + int read_bit(int bit_number); + + /** Read a 0/1 value from an input bit + * + * @param mask 16-bit mask value + * @return 16-bit data with mask applied + */ + int read_mask(unsigned short mask); + + /** Configure an MCP23017 device + * + * @param dir_config data direction value (1 = input, 0 = output) + * @param pullup_config 100k pullup value (1 = enabled, 0 = disabled) + * @param polarity_config polarity value (1 = flip, 0 = normal) + */ + void config(unsigned short dir_config, unsigned short pullup_config, unsigned short polarity_config); + + +/******************************************************************************* + * pinmode + * Set units to sequential, bank0 mode + */ + + void pinMode(int pin, int mode); + void digitalWrite(int pin, int val); + int digitalRead(int pin); + +// These provide a more advanced mapping of the chip functionality +// See the data sheet for more information on what they do + +//Returns a word with the current pin states (ie contents of the GPIO register) + unsigned short digitalWordRead(); +// Allows you to write a word to the GPIO register + void digitalWordWrite(unsigned short w); +// Sets up the polarity mask that the MCP23017 supports +// if set to 1, it will flip the actual pin value. + void inputPolarityMask(unsigned short mask); +//Sets which pins are inputs or outputs (1 = input, 0 = output) NB Opposite to arduino's +//definition for these + void inputOutputMask(unsigned short mask); +// Allows enabling of the internal 100k pullup resisters (1 = enabled, 0 = disabled) + void internalPullupMask(unsigned short mask); + + int read(void); + void write(int data); + void writeRegister(int regAddress, unsigned char val); + void writeRegister(int regAddress, unsigned short val); + int readRegister(int regAddress); + +protected: + I2C _i2c; + int MCP23017_i2cAddress; // physical I2C address + unsigned short shadow_GPIO, shadow_IODIR, shadow_GPPU, shadow_IPOL; // Cached copies of the register values + +}; + +#endif \ No newline at end of file