mirror of
https://github.com/DCC-EX/CommandStation-EX.git
synced 2024-12-24 13:21:23 +01:00
235 lines
8.9 KiB
C
235 lines
8.9 KiB
C
/*
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* © 2023, Neil McKechnie. All rights reserved.
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*
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* This file is part of CommandStation-EX
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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 I2CMANAGER_WIRE_H
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#define I2CMANAGER_WIRE_H
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#include <Arduino.h>
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#include <Wire.h>
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#include "I2CManager.h"
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// This module is only compiled if I2C_USE_WIRE is defined, so define it here
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// to get intellisense to work correctly.
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#if !defined(I2C_USE_WIRE)
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#define I2C_USE_WIRE
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#endif
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// Older versions of Wire don't have setWireTimeout function. AVR does.
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#ifdef ARDUINO_ARCH_AVR
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#define WIRE_HAS_TIMEOUT
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#endif
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/***************************************************************************
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* Initialise I2C interface software
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***************************************************************************/
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void I2CManagerClass::_initialise() {
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Wire.begin();
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#if defined(WIRE_HAS_TIMEOUT)
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Wire.setWireTimeout(_timeout, true);
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#endif
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}
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/***************************************************************************
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* Set I2C clock speed. Normally 100000 (Standard) or 400000 (Fast)
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* on Arduino. Mega4809 supports 1000000 (Fast+) too.
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***************************************************************************/
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void I2CManagerClass::_setClock(unsigned long i2cClockSpeed) {
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Wire.setClock(i2cClockSpeed);
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}
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/***************************************************************************
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* Set I2C timeout value in microseconds. The timeout applies to each
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* Wire call separately, i.e. in a write+read, the timer is reset before the
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* read is started.
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***************************************************************************/
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void I2CManagerClass::setTimeout(unsigned long value) {
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_timeout = value;
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#if defined(WIRE_HAS_TIMEOUT)
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Wire.setWireTimeout(value, true);
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#endif
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}
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/********************************************************
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* Helper function for I2C Multiplexer operations
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********************************************************/
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#ifdef I2C_EXTENDED_ADDRESS
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static uint8_t muxSelect(I2CAddress address) {
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// Select MUX sub bus.
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I2CMux muxNo = address.muxNumber();
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I2CSubBus subBus = address.subBus();
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if (muxNo != I2CMux_None) {
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Wire.beginTransmission(I2C_MUX_BASE_ADDRESS+muxNo);
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uint8_t data = (subBus == SubBus_All) ? 0xff :
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(subBus == SubBus_None) ? 0x00 :
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#if defined(I2CMUX_PCA9547)
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0x08 | subBus;
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#elif defined(I2CMUX_PCA9542) || defined(I2CMUX_PCA9544)
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0x04 | subBus; // NB Only 2 or 4 subbuses respectively
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#else
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// Default behaviour for most MUXs is to use a mask
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// with a bit set for the subBus to be enabled
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1 << subBus;
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#endif
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Wire.write(&data, 1);
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return Wire.endTransmission(true); // have to release I2C bus for it to work
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}
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return I2C_STATUS_OK;
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}
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#endif
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/***************************************************************************
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* Initiate a write to an I2C device (blocking operation on Wire)
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***************************************************************************/
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uint8_t I2CManagerClass::write(I2CAddress address, const uint8_t buffer[], uint8_t size, I2CRB *rb) {
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uint8_t status, muxStatus;
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uint8_t retryCount = 0;
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// If request fails, retry up to the defined limit, unless the NORETRY flag is set
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// in the request block.
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do {
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status = muxStatus = I2C_STATUS_OK;
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#ifdef I2C_EXTENDED_ADDRESS
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if (address.muxNumber() != I2CMux_None)
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muxStatus = muxSelect(address);
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#endif
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// Only send new transaction if address is non-zero.
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if (muxStatus == I2C_STATUS_OK && address != 0) {
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Wire.beginTransmission(address);
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if (size > 0) Wire.write(buffer, size);
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status = Wire.endTransmission();
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}
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#ifdef I2C_EXTENDED_ADDRESS
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// Deselect MUX if there's more than one MUX present, to avoid having multiple ones selected
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if (_muxCount > 1 && muxStatus == I2C_STATUS_OK
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&& address.deviceAddress() != 0 && address.muxNumber() != I2CMux_None) {
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muxSelect({address.muxNumber(), SubBus_None});
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}
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if (muxStatus != I2C_STATUS_OK) status = muxStatus;
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#endif
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} while (!(status == I2C_STATUS_OK
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|| ++retryCount > MAX_I2C_RETRIES || rb->operation & OPERATION_NORETRY));
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rb->status = status;
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return I2C_STATUS_OK;
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}
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/***************************************************************************
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* Initiate a write from PROGMEM (flash) to an I2C device (blocking operation on Wire)
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***************************************************************************/
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uint8_t I2CManagerClass::write_P(I2CAddress address, const uint8_t buffer[], uint8_t size, I2CRB *rb) {
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uint8_t ramBuffer[size];
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const uint8_t *p1 = buffer;
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for (uint8_t i=0; i<size; i++)
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ramBuffer[i] = GETFLASH(p1++);
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return write(address, ramBuffer, size, rb);
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}
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/***************************************************************************
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* Initiate a write (optional) followed by a read from the I2C device (blocking operation on Wire)
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* If fewer than the number of requested bytes are received, status is I2C_STATUS_TRUNCATED.
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***************************************************************************/
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uint8_t I2CManagerClass::read(I2CAddress address, uint8_t readBuffer[], uint8_t readSize,
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const uint8_t writeBuffer[], uint8_t writeSize, I2CRB *rb)
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{
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uint8_t status, muxStatus;
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uint8_t nBytes = 0;
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uint8_t retryCount = 0;
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// If request fails, retry up to the defined limit, unless the NORETRY flag is set
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// in the request block.
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do {
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status = muxStatus = I2C_STATUS_OK;
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#ifdef I2C_EXTENDED_ADDRESS
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if (address.muxNumber() != I2CMux_None) {
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muxStatus = muxSelect(address);
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}
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#endif
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// Only start new transaction if address is non-zero.
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if (muxStatus == I2C_STATUS_OK && address != 0) {
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if (writeSize > 0) {
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Wire.beginTransmission(address);
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Wire.write(writeBuffer, writeSize);
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status = Wire.endTransmission(false); // Don't free bus yet
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}
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if (status == I2C_STATUS_OK) {
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#ifdef WIRE_HAS_TIMEOUT
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Wire.clearWireTimeoutFlag();
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Wire.requestFrom(address, (size_t)readSize);
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if (!Wire.getWireTimeoutFlag()) {
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while (Wire.available() && nBytes < readSize)
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readBuffer[nBytes++] = Wire.read();
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if (nBytes < readSize) status = I2C_STATUS_TRUNCATED;
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} else {
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status = I2C_STATUS_TIMEOUT;
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}
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#else
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Wire.requestFrom(address, (size_t)readSize);
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while (Wire.available() && nBytes < readSize)
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readBuffer[nBytes++] = Wire.read();
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if (nBytes < readSize) status = I2C_STATUS_TRUNCATED;
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#endif
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}
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}
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#ifdef I2C_EXTENDED_ADDRESS
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// Deselect MUX if there's more than one MUX present, to avoid having multiple ones selected
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if (_muxCount > 1 && muxStatus == I2C_STATUS_OK && address != 0 && address.muxNumber() != I2CMux_None) {
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muxSelect({address.muxNumber(), SubBus_None});
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}
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if (muxStatus != I2C_STATUS_OK) status = muxStatus;
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#endif
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} while (!((status == I2C_STATUS_OK)
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|| ++retryCount > MAX_I2C_RETRIES || rb->operation & OPERATION_NORETRY));
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rb->nBytes = nBytes;
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rb->status = status;
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return I2C_STATUS_OK;
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}
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/***************************************************************************
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* Function to queue a request block and initiate operations.
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*
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* For the Wire version, this executes synchronously.
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* The read/write/write_P functions return I2C_STATUS_OK always, and the
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* completion status of the operation is in the request block, as for
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* the non-blocking version.
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***************************************************************************/
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void I2CManagerClass::queueRequest(I2CRB *req) {
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switch (req->operation & OPERATION_MASK) {
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case OPERATION_READ:
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read(req->i2cAddress, req->readBuffer, req->readLen, NULL, 0, req);
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break;
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case OPERATION_SEND:
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write(req->i2cAddress, req->writeBuffer, req->writeLen, req);
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break;
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case OPERATION_SEND_P:
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write_P(req->i2cAddress, req->writeBuffer, req->writeLen, req);
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break;
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case OPERATION_REQUEST:
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read(req->i2cAddress, req->readBuffer, req->readLen, req->writeBuffer, req->writeLen, req);
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break;
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}
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}
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/***************************************************************************
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* Loop function, for general background work
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***************************************************************************/
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void I2CManagerClass::loop() {}
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#endif
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