mirror of
https://github.com/DCC-EX/CommandStation-EX.git
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81 lines
2.9 KiB
C
81 lines
2.9 KiB
C
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/*
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* © 2021, Neil McKechnie. All rights reserved.
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*
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* This file is part of DCC++EX API
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*
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* This is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* It is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with CommandStation. If not, see <https://www.gnu.org/licenses/>.
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*/
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#ifndef IO_PCF8574_H
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#define IO_PCF8574_H
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#include "IO_GPIOBase.h"
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class PCF8574 : public GPIOBase<uint8_t> {
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public:
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static void create(VPIN firstVpin, uint8_t nPins, uint8_t I2CAddress, int interruptPin=-1) {
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new PCF8574(firstVpin, nPins, I2CAddress, interruptPin);
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}
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private:
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PCF8574(VPIN firstVpin, uint8_t nPins, uint8_t I2CAddress, int interruptPin=-1)
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: GPIOBase<uint8_t>((FSH *)F("PCF8574"), firstVpin, min(nPins, 8), I2CAddress, interruptPin)
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{
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requestBlock.setReadParams(_I2CAddress, inputBuffer, 1);
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}
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// The pin state is '1' if the pin is an input or if it is an output set to 1. Zero otherwise.
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void _writeGpioPort() override {
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I2CManager.write(_I2CAddress, 1, _portOutputState | ~_portMode);
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}
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// The PCF8574 handles inputs by applying a weak pull-up when output is driven to '1'.
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// Therefore, writing '1' in _writePortModes is enough to set the module to input mode
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// and enable pull-up.
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void _writePullups() override { }
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// The pin state is '1' if the pin is an input or if it is an output set to 1. Zero otherwise.
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void _writePortModes() override {
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I2CManager.write(_I2CAddress, 1, _portOutputState | ~_portMode);
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}
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// In immediate mode, _readGpioPort reads the device GPIO port and updates _portInputState accordingly.
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// When not in immediate mode, it initiates a request using the request block and returns.
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// When the request completes, _processCompletion finishes the operation.
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void _readGpioPort(bool immediate) override {
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if (immediate) {
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uint8_t buffer[1];
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I2CManager.read(_I2CAddress, buffer, 1);
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_portInputState = ((uint16_t)buffer) & 0xff;
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} else {
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requestBlock.wait(); // Wait for preceding operation to complete
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// Issue new request to read GPIO register
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I2CManager.queueRequest(&requestBlock);
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}
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}
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// This function is invoked when an I/O operation on the requestBlock completes.
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void _processCompletion(uint8_t status) override {
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if (status == I2C_STATUS_OK)
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_portInputState = ((uint16_t)inputBuffer[0]) & 0xff;
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else
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_portInputState = 0xff;
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}
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void _setupDevice() override { }
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uint8_t inputBuffer[1];
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};
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#endif
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