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- /*
- TwoWire.h - TWI/I2C library for Arduino & Wiring
- 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 December 2014 by Ivan Grokhotkov (ivan@esp8266.com) - esp8266 support
- Modified April 2015 by Hrsto Gochkov (ficeto@ficeto.com) - alternative esp8266 support
- Modified October 2016 by Marcelo Aquino <marceloaqno@gmail.org> for Raspberry Pi
- */
-
- #include "Wire.h"
- #include <stdlib.h>
- #include <pthread.h>
- #include "bcm2835.h"
- #include "log.h"
-
- static pthread_mutex_t i2cMutex = PTHREAD_MUTEX_INITIALIZER;
-
- uint8_t TwoWire::rxBuffer[BUFFER_LENGTH];
- uint8_t TwoWire::rxBufferIndex = 0;
- uint8_t TwoWire::rxBufferLength = 0;
-
- uint8_t TwoWire::txAddress = 0;
- uint8_t TwoWire::txBuffer[BUFFER_LENGTH];
- uint8_t TwoWire::txBufferIndex = 0;
- uint8_t TwoWire::txBufferLength = 0;
-
- uint8_t TwoWire::transmitting = 0;
-
- void TwoWire::begin()
- {
- if (!bcm2835_i2c_begin()) {
- logError("You need root privilege to use I2C.\n");
- exit(1);
- }
- }
-
- void TwoWire::begin(uint8_t address)
- {
- begin();
- bcm2835_i2c_setSlaveAddress(address);
- }
-
- void TwoWire::begin(int address)
- {
- begin(static_cast<uint8_t>(address));
- }
-
- void TwoWire::end()
- {
- bcm2835_i2c_end();
- }
-
- void TwoWire::setClock(uint32_t clock)
- {
- bcm2835_i2c_set_baudrate(clock);
- }
-
- void TwoWire::beginTransmission(uint8_t address)
- {
- pthread_mutex_lock(&i2cMutex);
- // indicate that we are transmitting
- transmitting = 1;
- // set address of targeted slave
- txAddress = address;
- // reset tx buffer iterator vars
- txBufferIndex = 0;
- txBufferLength = 0;
- }
-
- void TwoWire::beginTransmission(int address)
- {
- beginTransmission(static_cast<uint8_t>(address));
- }
-
- uint8_t TwoWire::endTransmission(void)
- {
- // transmit buffer
- bcm2835_i2c_setSlaveAddress(txAddress);
- uint8_t ret = bcm2835_i2c_write(reinterpret_cast<const char *>(txBuffer), txBufferLength);
-
- // reset tx buffer iterator vars
- txBufferIndex = 0;
- txBufferLength = 0;
- // indicate that we are done transmitting
- transmitting = 0;
-
- pthread_mutex_unlock(&i2cMutex);
-
- if (ret == BCM2835_I2C_REASON_OK) {
- return 0; // success
- } else if (ret == BCM2835_I2C_REASON_ERROR_NACK) {
- return 3; // error: data send, nack received
- }
- return 4; // other error
- }
-
- size_t TwoWire::requestFrom(uint8_t address, size_t quantity)
- {
- // clamp to buffer length
- if (quantity > BUFFER_LENGTH) {
- quantity = BUFFER_LENGTH;
- }
-
- rxBufferIndex = 0;
- rxBufferLength = 0;
-
- bcm2835_i2c_setSlaveAddress(address);
- uint8_t ret = bcm2835_i2c_read(reinterpret_cast<char *>(rxBuffer), quantity);
- if (ret == BCM2835_I2C_REASON_OK) {
- rxBufferLength = quantity;
- }
-
- return rxBufferLength;
- }
-
- uint8_t TwoWire::requestFrom(uint8_t address, uint8_t quantity)
- {
- return requestFrom(address, static_cast<size_t>(quantity));
- }
-
- uint8_t TwoWire::requestFrom(int address, int quantity)
- {
- return requestFrom(static_cast<uint8_t>(address), static_cast<size_t>(quantity));
- }
-
- size_t TwoWire::write(uint8_t data)
- {
- if (transmitting) {
- // in master transmitter mode
- // don't bother if buffer is full
- if (txBufferLength >= BUFFER_LENGTH) {
- setWriteError();
- return 0;
- }
- // put byte in tx buffer
- txBuffer[txBufferIndex] = data;
- ++txBufferIndex;
- // update amount in buffer
- txBufferLength = txBufferIndex;
-
- return 1;
- } else {
- return write(&data, 1);
- }
- }
-
- size_t TwoWire::write(const uint8_t *data, size_t quantity)
- {
- if (transmitting) {
- // in master transmitter mode
- for (size_t i = 0; i < quantity; ++i) {
- write(data[i]);
- }
- } else {
- uint8_t rc = bcm2835_i2c_write(reinterpret_cast<const char *>(data), quantity);
- if (rc != BCM2835_I2C_REASON_OK) {
- return 0;
- }
- }
-
- return quantity;
- }
-
- int TwoWire::available()
- {
- return rxBufferLength - rxBufferIndex;
- }
-
- int TwoWire::read()
- {
- int value = -1;
-
- if (rxBufferIndex < rxBufferLength) {
- value = rxBuffer[rxBufferIndex];
- ++rxBufferIndex;
- }
-
- return value;
- }
-
- int TwoWire::peek()
- {
- if (rxBufferIndex < rxBufferLength) {
- return rxBuffer[rxBufferIndex];
- }
-
- return -1;
- }
-
- void TwoWire::flush()
- {
- rxBufferIndex = 0;
- rxBufferLength = 0;
- txBufferIndex = 0;
- txBufferLength = 0;
- }
-
- TwoWire Wire = TwoWire();
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