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IO_MCP23008.h
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IO_MCP23008.h
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/*
* © 2022 Paul M Antoine
* © 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_MCP23008_H
#define IO_MCP23008_H
#include "IO_GPIOBase.h"
class MCP23008 : public GPIOBase<uint8_t> {
public:
static void create(VPIN firstVpin, uint8_t nPins, I2CAddress i2cAddress, int interruptPin=-1) {
if (checkNoOverlap(firstVpin, nPins,i2cAddress)) new MCP23008(firstVpin, nPins, i2cAddress, interruptPin);
}
private:
// Constructor
MCP23008(VPIN firstVpin, uint8_t nPins, I2CAddress i2cAddress, int interruptPin=-1)
: GPIOBase<uint8_t>((FSH *)F("MCP23008"), firstVpin, nPins, i2cAddress, interruptPin) {
requestBlock.setRequestParams(_I2CAddress, inputBuffer, sizeof(inputBuffer),
outputBuffer, sizeof(outputBuffer));
outputBuffer[0] = REG_GPIO;
}
void _writeGpioPort() override {
I2CManager.write(_I2CAddress, 2, REG_GPIO, _portOutputState);
}
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.
I2CManager.write(_I2CAddress, 2, REG_GPPU, _portPullup & _portInUse);
}
void _writePortModes() override {
// Write 0 to IODIR for in-use pins that are outputs, 1 for others.
uint8_t temp = ~(_portMode & _portInUse);
I2CManager.write(_I2CAddress, 2, REG_IODIR, temp);
// Enable interrupt-on-change for in-use pins that are inputs (_portMode=0)
temp = ~_portMode & _portInUse;
I2CManager.write(_I2CAddress, 2, REG_INTCON, 0x00);
I2CManager.write(_I2CAddress, 2, REG_GPINTEN, temp);
}
void _readGpioPort(bool immediate) override {
if (immediate) {
uint8_t buffer;
I2CManager.read(_I2CAddress, &buffer, 1, 1, REG_GPIO);
_portInputState = buffer | _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 = inputBuffer[0] | _portMode;
else
_portInputState = 0xff;
}
void _setupDevice() override {
// IOCON is set ODR=1 (open drain shared interrupt pin), INTPOL=0 (active-Low)
I2CManager.write(_I2CAddress, 2, REG_IOCON, 0x04);
_writePortModes();
_writePullups();
_writeGpioPort();
}
uint8_t inputBuffer[1];
uint8_t outputBuffer[1];
enum {
// Register definitions for MCP23008
REG_IODIR=0x00,
REG_GPINTEN=0x02,
REG_INTCON=0x04,
REG_IOCON=0x05,
REG_GPPU=0x06,
REG_GPIO=0x09,
};
};
#endif