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IO_MCP23017.h
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IO_MCP23017.h
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/*
* © 2021, Neil McKechnie. All rights reserved.
*
* This file is part of DCC++EX API
*
* This 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.
*
* It 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 CommandStation. If not, see <https://www.gnu.org/licenses/>.
*/
#ifndef io_mcp23017_h
#define io_mcp23017_h
#include "IO_GPIOBase.h"
#include "FSH.h"
/////////////////////////////////////////////////////////////////////////////////////////////////////
/*
* IODevice subclass for MCP23017 16-bit I/O expander.
*/
class MCP23017 : public GPIOBase<uint16_t> {
public:
static void create(VPIN vpin, uint8_t nPins, I2CAddress i2cAddress, int interruptPin=-1) {
if (checkNoOverlap(vpin, nPins, i2cAddress)) new MCP23017(vpin, nPins, i2cAddress, interruptPin);
}
private:
// Constructor
MCP23017(VPIN vpin, uint8_t nPins, I2CAddress i2cAddress, int interruptPin=-1)
: GPIOBase<uint16_t>((FSH *)F("MCP23017"), vpin, nPins, i2cAddress, interruptPin)
{
requestBlock.setRequestParams(_I2CAddress, inputBuffer, sizeof(inputBuffer),
outputBuffer, sizeof(outputBuffer));
outputBuffer[0] = REG_GPIOA;
}
void _writeGpioPort() override {
I2CManager.write(_I2CAddress, 3, REG_GPIOA, _portOutputState, _portOutputState>>8);
}
void _writePullups() override {
// Set pullups only for in-use pins. This prevents pullup being set for a pin that
// is intended for use as an output but hasn't been written to yet.
uint16_t temp = _portPullup & _portInUse;
I2CManager.write(_I2CAddress, 3, REG_GPPUA, temp, temp>>8);
}
void _writePortModes() override {
// Write 0 to IODIR for in-use pins that are outputs, 1 for others.
uint16_t temp = ~(_portMode & _portInUse);
I2CManager.write(_I2CAddress, 3, REG_IODIRA, temp, temp>>8);
// Enable interrupt for in-use pins which are inputs (_portMode=0)
temp = ~_portMode & _portInUse;
I2CManager.write(_I2CAddress, 3, REG_INTCONA, 0x00, 0x00);
I2CManager.write(_I2CAddress, 3, REG_GPINTENA, temp, temp>>8);
}
void _readGpioPort(bool immediate) override {
if (immediate) {
uint8_t buffer[2];
I2CManager.read(_I2CAddress, buffer, 2, 1, REG_GPIOA);
_portInputState = ((uint16_t)buffer[1]<<8) | buffer[0] | _portMode;
} else {
// Queue new request
requestBlock.wait(); // Wait for preceding operation to complete
// Issue new request to read GPIO register
I2CManager.queueRequest(&requestBlock);
}
}
// This function is invoked when an I/O operation on the requestBlock completes.
void _processCompletion(uint8_t status) override {
if (status == I2C_STATUS_OK)
_portInputState = (((uint16_t)inputBuffer[1]<<8) | inputBuffer[0]) | _portMode;
else
_portInputState = 0xffff;
}
void _setupDevice() override {
// IOCON is set MIRROR=1, ODR=1 (open drain shared interrupt pin)
I2CManager.write(_I2CAddress, 2, REG_IOCON, 0x44);
_writePortModes();
_writePullups();
_writeGpioPort();
}
uint8_t inputBuffer[2];
uint8_t outputBuffer[1];
enum {
REG_IODIRA = 0x00,
REG_IODIRB = 0x01,
REG_GPINTENA = 0x04,
REG_GPINTENB = 0x05,
REG_INTCONA = 0x08,
REG_INTCONB = 0x09,
REG_IOCON = 0x0A,
REG_GPPUA = 0x0C,
REG_GPPUB = 0x0D,
REG_GPIOA = 0x12,
REG_GPIOB = 0x13,
};
};
#endif