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Wire.cpp
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Wire.cpp
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/*
TwoWire.cpp - TWI/I2C library for Wiring & Arduino
Copyright (c) 2006 Nicholas Zambetti. All right reserved.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
Modified 2012 by Todd Krein (todd@krein.org) to implement repeated starts
Modified 6 june 2023 by Temperslee to support wch's risc-v chips
*/
extern "C" {
#include <stdlib.h>
#include <string.h>
#include <inttypes.h>
}
#include "Wire.h"
// Distinguish master from slave.
// 0x01 is a reserved value, and thus cannot be used by slave devices
static const uint8_t MASTER_ADDRESS = 0x01;
// Constructors ////////////////////////////////////////////////////////////////
TwoWire::TwoWire()
{
_i2c.sda = digitalPinToPinName(SDA);
_i2c.scl = digitalPinToPinName(SCL);
}
TwoWire::TwoWire(uint32_t sda, uint32_t scl)
{
_i2c.sda = digitalPinToPinName(sda);
_i2c.scl = digitalPinToPinName(scl);
}
// Public Methods //////////////////////////////////////////////////////////////
void TwoWire::begin(uint32_t sda, uint32_t scl)
{
_i2c.sda = digitalPinToPinName(sda);
_i2c.scl = digitalPinToPinName(scl);
begin();
}
void TwoWire::begin(bool generalCall)
{
begin(MASTER_ADDRESS, generalCall);
}
void TwoWire::begin(uint8_t address, bool generalCall, bool NoStretchMode)
{
rxBufferIndex = 0;
rxBufferLength = 0;
rxBuffer = nullptr;
rxBufferAllocated = 0;
resetRxBuffer();
txDataSize = 0;
txAddress = 0;
txBuffer = nullptr;
txBufferAllocated = 0;
resetTxBuffer();
_i2c.__this = (void *)this;
// user_onRequest = NULL;
transmitting = 0;
ownAddress = address << 1;
_i2c.isMaster = (address == MASTER_ADDRESS) ? 1 : 0;
_i2c.generalCall = (generalCall == true) ? 1 : 0;
_i2c.NoStretchMode = (NoStretchMode == true) ? 1 : 0;
recoverBus(); // in case I2C bus (device) is stuck after a reset for example
i2c_custom_init(&_i2c, 100000, I2C_AcknowledgedAddress_7bit, ownAddress);
if (_i2c.isMaster == 0)
{
// i2c_attachSlaveTxEvent(&_i2c, reinterpret_cast<void(*)(i2c_t*)>(&TwoWire::onRequestService));
// i2c_attachSlaveRxEvent(&_i2c, reinterpret_cast<void(*)(i2c_t*, uint8_t*, int)>(&TwoWire::onReceiveService));
// i2c_attachSlaveTxEvent(&_i2c, onRequestService);
// i2c_attachSlaveRxEvent(&_i2c, onReceiveService);
}
}
void TwoWire::begin(int address, bool generalCall, bool NoStretchMode)
{
begin((uint8_t)address, generalCall, NoStretchMode);
}
void TwoWire::end(void)
{
i2c_deinit(&_i2c);
free(txBuffer);
txBuffer = nullptr;
txBufferAllocated = 0;
free(rxBuffer);
rxBuffer = nullptr;
rxBufferAllocated = 0;
}
void TwoWire::setClock(uint32_t frequency)
{
i2c_setTiming(&_i2c, frequency);
if (_i2c.isMaster == 0) {
// i2c_attachSlaveTxEvent(&_i2c, onRequestService);
// i2c_attachSlaveRxEvent(&_i2c, onReceiveService);
}
}
uint8_t TwoWire::requestFrom(uint8_t address, uint8_t quantity, uint32_t iaddress, uint8_t isize, uint8_t sendStop)
{
uint8_t read = 0;
if (_i2c.isMaster == 1) {
allocateRxBuffer(quantity);
if (isize > 0) {
// send internal address; this mode allows sending a repeated start to access
// some devices' internal registers. This function is executed by the hardware
// TWI module on other processors (for example Due's TWI_IADR and TWI_MMR registers)
beginTransmission(address);
// the maximum size of internal address is 3 bytes
if (isize > 3)
{
isize = 3;
}
// write internal register address - most significant byte first
while (isize-- > 0) {
write((uint8_t)(iaddress >> (isize * 8)));
}
endTransmission( 0 ); //without stop
}
if (I2C_OK == i2c_master_read(&_i2c, address << 1, rxBuffer, quantity)) {
read = quantity;
}
// set rx buffer iterator vars
rxBufferIndex = 0;
rxBufferLength = read;
}
return read;
}
uint8_t TwoWire::requestFrom(uint8_t address, uint8_t quantity, uint8_t sendStop)
{
return requestFrom((uint8_t)address, (uint8_t)quantity, (uint32_t)0, (uint8_t)0, (uint8_t)sendStop);
}
uint8_t TwoWire::requestFrom(uint8_t address, size_t quantity, bool sendStop)
{
return requestFrom((uint8_t)address, (uint8_t)quantity, (uint8_t)sendStop);
}
uint8_t TwoWire::requestFrom(uint8_t address, uint8_t quantity)
{
return requestFrom((uint8_t)address, (uint8_t)quantity, (uint8_t)true);
}
uint8_t TwoWire::requestFrom(int address, int quantity)
{
return requestFrom((uint8_t)address, (uint8_t)quantity, (uint8_t)true);
}
uint8_t TwoWire::requestFrom(int address, int quantity, int sendStop)
{
return requestFrom((uint8_t)address, (uint8_t)quantity, (uint8_t)sendStop);
}
void TwoWire::beginTransmission(uint8_t address)
{
// indicate that we are transmitting
transmitting = 1;
// set address of targeted slave
txAddress = address << 1;
// reset tx data size
txDataSize = 0;
}
void TwoWire::beginTransmission(int address)
{
beginTransmission((uint8_t)address);
}
//
// Originally, 'endTransmission' was an f(void) function.
// It has been modified to take one parameter indicating
// whether or not a STOP should be performed on the bus.
// Calling endTransmission(false) allows a sketch to
// perform a repeated start.
//
// WARNING: Nothing in the library keeps track of whether
// the bus tenure has been properly ended with a STOP. It
// is very possible to leave the bus in a hung state if
// no call to endTransmission(true) is made. Some I2C
// devices will behave oddly if they do not see a STOP.
//
uint8_t TwoWire::endTransmission(uint8_t sendStop)
{
int8_t ret = 4;
if (_i2c.isMaster == 1)
{
// transmit buffer (blocking)
switch (i2c_master_write(&_i2c, txAddress, txBuffer, txDataSize, sendStop))
{
case I2C_OK :
ret = 0; // Success
break;
case I2C_DATA_TOO_LONG :
ret = 1;
break;
case I2C_NACK_ADDR:
ret = 2;
break;
case I2C_NACK_DATA:
ret = 3;
break;
case I2C_TIMEOUT:
case I2C_BUSY:
case I2C_ERROR:
default:
ret = 4;
break;
}
// reset Tx buffer
resetTxBuffer();
// reset tx buffer data size
txDataSize = 0;
// indicate that we are done transmitting
transmitting = 0;
}
return ret;
}
// This provides backwards compatibility with the original
// definition, and expected behaviour, of endTransmission
// complete and end a transfer
uint8_t TwoWire::endTransmission(void)
{
return endTransmission((uint8_t)true);
}
// must be called in:
// slave tx event callback
// or after beginTransmission(address)
size_t TwoWire::write(uint8_t data)
{
size_t ret = 1;
if (transmitting) {
// in master transmitter mode
if (allocateTxBuffer(txDataSize + 1) == 0) {
ret = 0;
} else {
// put byte in tx buffer
txBuffer[txDataSize] = data;
// update amount in buffer
txDataSize++;
}
} else {
// in slave send mode
// reply to master
if (i2c_slave_write(&_i2c, &data, 1) != I2C_OK) {
ret = 0;
}
}
return ret;
}
/**
* @brief This function must be called in slave Tx event callback or after
* beginTransmission() and before endTransmission().
* @param pdata: pointer to the buffer data
* @param quantity: number of bytes to write
* @retval number of bytes ready to write.
*/
size_t TwoWire::write(const uint8_t *data, size_t quantity)
{
size_t ret = quantity;
if (transmitting) {
// in master transmitter mode
if (allocateTxBuffer(txDataSize + quantity) == 0) {
ret = 0;
} else {
// put bytes in tx buffer
memcpy(&(txBuffer[txDataSize]), data, quantity);
// update amount in buffer
txDataSize += quantity;
}
} else {
// in slave send mode
// reply to master
if (i2c_slave_write(&_i2c, (uint8_t *)data, quantity) != I2C_OK) {
ret = 0;
}
}
return ret;
}
// must be called in:
// slave rx event callback
// or after requestFrom(address, numBytes)
int TwoWire::available(void)
{
return rxBufferLength - rxBufferIndex;
}
// must be called in:
// slave rx event callback
// or after requestFrom(address, numBytes)
int TwoWire::read(void)
{
int value = -1;
// get each successive byte on each call
if (rxBufferIndex < rxBufferLength) {
value = rxBuffer[rxBufferIndex];
++rxBufferIndex;
/* Commented as not I think it is not useful
* but kept to show that it is possible to
* reset rx buffer when no more data available */
/*if(rxBufferIndex == rxBufferLength) {
resetRxBuffer();
}*/
}
return value;
}
// must be called in:
// slave rx event callback
// or after requestFrom(address, numBytes)
int TwoWire::peek(void)
{
int value = -1;
if (rxBufferIndex < rxBufferLength) {
value = rxBuffer[rxBufferIndex];
}
return value;
}
void TwoWire::flush(void)
{
rxBufferIndex = 0;
rxBufferLength = 0;
resetRxBuffer();
txDataSize = 0;
resetTxBuffer();
}
// behind the scenes function that is called when data is received
void TwoWire::onReceiveService(i2c_t *obj)
{
uint8_t *inBytes = (uint8_t *) obj->i2cTxRxBuffer;
int numBytes = obj->slaveRxNbData;
TwoWire *TW = (TwoWire *)(obj->__this);
// don't bother if user hasn't registered a callback
if (TW->user_onReceive) {
// don't bother if rx buffer is in use by a master requestFrom() op
// i know this drops data, but it allows for slight stupidity
// meaning, they may not have read all the master requestFrom() data yet
if (TW->rxBufferIndex >= TW->rxBufferLength) {
TW->allocateRxBuffer(numBytes);
// copy twi rx buffer into local read buffer
// this enables new reads to happen in parallel
memcpy(TW->rxBuffer, inBytes, numBytes);
// set rx iterator vars
TW->rxBufferIndex = 0;
TW->rxBufferLength = numBytes;
// alert user program
TW->user_onReceive(numBytes);
}
}
}
// behind the scenes function that is called when data is requested
void TwoWire::onRequestService(i2c_t *obj)
{
TwoWire *TW = (TwoWire *)(obj->__this);
// don't bother if user hasn't registered a callback
if (TW->user_onRequest) {
// reset tx data size
// !!! this will kill any pending pre-master sendTo() activity
TW->txDataSize = 0;
// alert user program
TW->user_onRequest();
}
}
// sets function called on slave write
void TwoWire::onReceive(cb_function_receive_t function)
{
user_onReceive = function;
}
// sets function called on slave read
void TwoWire::onRequest(cb_function_request_t function)
{
user_onRequest = function;
}
/**
* @brief Allocate the Rx/Tx buffer to the requested length if needed
* @note Minimum allocated size is BUFFER_LENGTH)
* @param length: number of bytes to allocate
*/
void TwoWire::allocateRxBuffer(size_t length)
{
if (rxBufferAllocated < length) {
// By default we allocate BUFFER_LENGTH bytes. It is the min size of the buffer.
if (length < BUFFER_LENGTH) {
length = BUFFER_LENGTH;
}
uint8_t *tmp = (uint8_t *)realloc(rxBuffer, length * sizeof(uint8_t));
if (tmp != nullptr) {
rxBuffer = tmp;
rxBufferAllocated = length;
} else {
_Error_Handler("No enough memory! (%i)\n", length);
}
}
}
inline size_t TwoWire::allocateTxBuffer(size_t length)
{
size_t ret = length;
if (length > WIRE_MAX_TX_BUFF_LENGTH) {
ret = 0;
} else if (txBufferAllocated < length) {
// By default we allocate BUFFER_LENGTH bytes. It is the min size of the buffer.
if (length < BUFFER_LENGTH) {
length = BUFFER_LENGTH;
}
uint8_t *tmp = (uint8_t *)realloc(txBuffer, length * sizeof(uint8_t));
if (tmp != nullptr) {
txBuffer = tmp;
txBufferAllocated = length;
} else {
_Error_Handler("No enough memory! (%i)\n", length);
}
}
return ret;
}
/**
* @brief Reset Rx/Tx buffer content to 0
*/
inline void TwoWire::resetRxBuffer(void)
{
if (rxBuffer != nullptr) {
memset(rxBuffer, 0, rxBufferAllocated);
}
}
inline void TwoWire::resetTxBuffer(void)
{
if (txBuffer != nullptr) {
memset(txBuffer, 0, txBufferAllocated);
}
}
// Send clear bus (clock pulse) sequence to recover bus.
// Useful in case of bus stuck after a reset for example
// a mix implementation of Clear Bus from
// https://www.nxp.com/docs/en/user-guide/UM10204.pdf
// https://bits4device.wordpress.com/2017/07/28/i2c-bus-recovery/
void TwoWire::recoverBus(void)
{
pinMode(pinNametoDigitalPin(_i2c.sda), INPUT);
if (digitalReadFast(_i2c.sda) == LOW) {
pinMode(pinNametoDigitalPin(_i2c.scl), OUTPUT);
for (int i = 0; i < 20; i++) {
digitalWriteFast(_i2c.scl, LOW);
delayMicroseconds(10);
digitalWriteFast(_i2c.scl, HIGH);
delayMicroseconds(10);
}
pinMode(pinNametoDigitalPin(_i2c.scl), INPUT);
}
}
// Preinstantiate Objects //////////////////////////////////////////////////////
TwoWire Wire = TwoWire( );