Basic library to interface to a Microchip MCP23016 I/O expander using I2C
Testing code to blink 2 lights
#include "mbed.h" #include "MCP23016.h" MCP23016 PortExpand(D4, D5, 0); DigitalOut myled(LED1); int main() { PortExpand.pinMode(0, DIR_OUTPUT); PortExpand.pinMode(8, DIR_OUTPUT); while(1) { PortExpand.digitalWrite(0, 1); PortExpand.digitalWrite(8, 0); myled = 1; // LED is ON wait(1); // 200 ms PortExpand.digitalWrite(0, 0); PortExpand.digitalWrite(8, 1); myled = 0; // LED is OFF wait(1); // 1 sec } }
MCP23016.cpp
- Committer:
- davidr99
- Date:
- 2016-01-19
- Revision:
- 0:133b7e09bbe7
File content as of revision 0:133b7e09bbe7:
/* MCP23016 library Based on MCP23017 library for arduino by 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 "MCP23016.h" #include "mbed.h" union { uint8_t value8[2]; uint16_t value16; } tmp_data; /*----------------------------------------------------------------------------- * */ MCP23016::MCP23016(PinName sda, PinName scl, int i2cAddress) : _i2c(sda, scl) { MCP23016_i2cAddress = I2C_BASE_ADDRESS + i2cAddress; reset(); // initialise chip to power-on condition } /*----------------------------------------------------------------------------- * reset * Set configuration (IOCON) and direction(IODIR) registers to initial state */ void MCP23016::reset() { // // set direction registers to inputs // writeRegister(IODIR0, (unsigned short)0xFFFF); // // set all other registers to zero (last of 10 registers is OLAT) // for (int reg_addr = OLAT0 ; reg_addr <= IPOL1 ; reg_addr+=2) { writeRegister(reg_addr, (unsigned short)0x0000); } // // Set the shadow registers to power-on state // shadow_IODIR = 0xFFFF; shadow_GPIO = 0; shadow_IPOL = 0; } /*----------------------------------------------------------------------------- * write_bit * Write a 1/0 to a single bit of the 16-bit port */ void MCP23016::write_bit(int value, int bit_number) { if (value == 0) { shadow_GPIO &= ~(1 << bit_number); } else { shadow_GPIO |= 1 << bit_number; } writeRegister(OLAT0, (unsigned short)shadow_GPIO); } /*----------------------------------------------------------------------------- * Write a combination of bits to the 16-bit port */ void MCP23016::write_mask(unsigned short data, unsigned short mask) { shadow_GPIO = (shadow_GPIO & ~mask) | data; writeRegister(OLAT0, (unsigned short)shadow_GPIO); } /*----------------------------------------------------------------------------- * read_bit * Read a single bit from the 16-bit port */ int MCP23016::read_bit(int bit_number) { shadow_GPIO = readRegister(GP0); return ((shadow_GPIO >> bit_number) & 0x0001); } /*----------------------------------------------------------------------------- * read_mask */ int MCP23016::read_mask(unsigned short mask) { shadow_GPIO = readRegister(GP0); return (shadow_GPIO & mask); } /*----------------------------------------------------------------------------- * Config * set direction and pull-up registers */ void MCP23016::config(unsigned short dir_config, unsigned short polarity_config) { shadow_IODIR = dir_config; writeRegister(IODIR0, (unsigned short)shadow_IODIR); shadow_IPOL = polarity_config; writeRegister(IPOL0, (unsigned short)shadow_IPOL); } /*----------------------------------------------------------------------------- * writeRegister * write a byte */ void MCP23016::writeRegister(int regAddress, unsigned char data) { char buffer[2]; buffer[0] = regAddress; buffer[1] = data; _i2c.write(MCP23016_i2cAddress, buffer, 2); } /*---------------------------------------------------------------------------- * write Register * write two bytes */ void MCP23016::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(MCP23016_i2cAddress, buffer, 3); } /*----------------------------------------------------------------------------- * readRegister */ int MCP23016::readRegister(int regAddress) { char buffer[2]; buffer[0] = regAddress; _i2c.write(MCP23016_i2cAddress, buffer, 1); _i2c.read(MCP23016_i2cAddress, buffer, 2); return ((int)(buffer[0] + (buffer[1]<<8))); } /*----------------------------------------------------------------------------- * pinMode */ void MCP23016::pinMode(int pin, int mode) { if (mode == DIR_INPUT) { shadow_IODIR |= 1 << pin; } else { shadow_IODIR &= ~(1 << pin); } writeRegister(IODIR0, (unsigned short)shadow_IODIR); } /*----------------------------------------------------------------------------- * digitalRead */ int MCP23016::digitalRead(int pin) { shadow_GPIO = readRegister(GP0); if ( shadow_GPIO & (1 << pin)) { return 1; } else { return 0; } } /*----------------------------------------------------------------------------- * digitalWrite */ void MCP23016::digitalWrite(int pin, int val) { // This 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(OLAT0, (unsigned short)shadow_GPIO); } } /*----------------------------------------------------------------------------- * digitalWordRead */ unsigned short MCP23016::digitalWordRead() { shadow_GPIO = readRegister(GP0); return shadow_GPIO; } /*----------------------------------------------------------------------------- * digitalWordWrite */ void MCP23016::digitalWordWrite(unsigned short w) { shadow_GPIO = w; writeRegister(OLAT0, (unsigned short)shadow_GPIO); } /*----------------------------------------------------------------------------- * inputPolarityMask */ void MCP23016::inputPolarityMask(unsigned short mask) { writeRegister(IPOL0, mask); } /*----------------------------------------------------------------------------- * inputoutputMask */ void MCP23016::inputOutputMask(unsigned short mask) { shadow_IODIR = mask; writeRegister(IODIR0, (unsigned short)shadow_IODIR); }