mirror of
https://github.com/DCC-EX/CommandStation-EX.git
synced 2024-11-25 09:06:13 +01:00
4f16a4ca06
Previously, pullups were enabled on GPIO Expander digital pins by default, even if the pin was only ever used as an output. This could lead to a spurious HIGH state being seen by external equipment before the output is initialised to LOW. To avoid this, the pin pullup is now not enabled until a configure or read operation is issued for the pin.
112 lines
3.7 KiB
C++
112 lines
3.7 KiB
C++
/*
|
|
* © 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, int nPins, uint8_t I2CAddress, int interruptPin=-1) {
|
|
new MCP23017(vpin, min(nPins,16), I2CAddress, interruptPin);
|
|
}
|
|
|
|
// Constructor
|
|
MCP23017(VPIN vpin, int nPins, uint8_t 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;
|
|
}
|
|
|
|
private:
|
|
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];
|
|
} 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];
|
|
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 |