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feat: Breakout I2C Implementation (#47)
Splits out I2C only functionality Creates I2C Interface Unit-tests and test harness Extends mocking capability Adds test run for `WIRE_HAS_MOCK`
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-561
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‎.gitignore

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.vscode/
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.DS_Store
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*.gch
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*.out
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Doxyfile*

‎src/NoteI2c.hpp

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#ifndef NOTE_I2C_HPP
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#define NOTE_I2C_HPP
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#include <stddef.h>
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#include <stdint.h>
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#include "Notecard.h"
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class NoteI2c {
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public:
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/**************************************************************************/
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/*!
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@brief Type used to abstract specific hardware implementation types.
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*/
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/**************************************************************************/
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typedef void * bus_t;
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virtual ~NoteI2c(void) {}
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/**************************************************************************/
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/*!
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@brief Receives an amount of data from the Notecard in blocking mode.
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@param[in] device_address
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The I2C address.
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@param[out] buffer
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A buffer to hold the data read from the I2C controller.
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@param[in] requested_byte_count
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The number of bytes requested.
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@param[out] available
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The number of bytes available for subsequent calls to receive().
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@returns A string with an error, or `nullptr` if the receive was
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successful.
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*/
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/**************************************************************************/
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virtual const char * receive(uint16_t device_address, uint8_t * buffer, uint16_t size, uint32_t * available) = 0;
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/**************************************************************************/
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/*!
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@brief Resets the I2C port. Required by note-c.
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@return `true`.
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*/
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/**************************************************************************/
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virtual bool reset(uint16_t device_address) = 0;
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/**************************************************************************/
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/*!
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@brief Transmits an amount of data from the host in blocking mode.
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@param[in] device_address
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The I2C address.
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@param[in] buffer
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The data to transmit over I2C. The caller should have shifted
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it right so that the low bit is NOT the read/write bit.
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@param[in] size
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The number of bytes to transmit.
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@returns A string with an error, or `nullptr` if the transmission was
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successful.
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*/
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/**************************************************************************/
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virtual const char * transmit(uint16_t device_address, uint8_t * buffer, uint16_t size) = 0;
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/**************************************************************************/
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/*!
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@brief Size of the header for Serial-Over-I2C requests.
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@details The request made to the low-level I2C controller should be
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for REQUEST_HEADER_SIZE + the `size` parameter supplied to the
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`receive` method.
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@see NoteI2c::receive
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*/
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/**************************************************************************/
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static const size_t REQUEST_HEADER_SIZE = 2;
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};
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/******************************************************************************/
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/*!
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@brief Helper function to abstract, create and maintain a single instance
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of the NoteI2c interface implementation, as required by the underlying
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`note-c` library.
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@param[in] i2c_bus Pointer to the hardware specific I2C bus implementation.
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*/
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/******************************************************************************/
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NoteI2c * make_note_i2c (
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NoteI2c::bus_t i2c_bus
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);
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#endif // NOTE_I2C_HPP

‎src/NoteI2c_Arduino.cpp

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#include "NoteI2c_Arduino.hpp"
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#if defined(NOTE_LOWMEM)
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static const char *i2cerr = "i2c {io}";
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#endif
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NoteI2c *
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make_note_i2c (
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NoteI2c::bus_t i2c_bus_
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) {
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static NoteI2c * note_i2c = nullptr;
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if (note_i2c) {
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delete note_i2c;
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}
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note_i2c = new NoteI2c_Arduino(*reinterpret_cast<TwoWire *>(i2c_bus_));
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return note_i2c;
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}
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NoteI2c_Arduino::NoteI2c_Arduino
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(
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TwoWire & i2c_bus_
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) :
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_i2cPort(i2c_bus_)
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{
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_i2cPort.begin();
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}
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const char *
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NoteI2c_Arduino::receive (
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uint16_t device_address_,
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uint8_t * buffer_,
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uint16_t requested_byte_count_,
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uint32_t * available_
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) {
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const char *result = nullptr;
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uint8_t transmission_error = 0;
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// Request response data from Notecard
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for (size_t i = 0 ; i < 3 ; ++i) {
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_i2cPort.beginTransmission(static_cast<uint8_t>(device_address_));
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_i2cPort.write(0);
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_i2cPort.write(static_cast<uint8_t>(requested_byte_count_));
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transmission_error = _i2cPort.endTransmission();
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// Break out of loop on success
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if (!transmission_error) {
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break;
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}
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switch (transmission_error) {
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case 1:
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result = ERRSTR("i2c: data too long to fit in transmit buffer {io}",i2cerr);
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break;
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case 2:
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result = ERRSTR("i2c: received NACK on transmit of address {io}",i2cerr);
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break;
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case 3:
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result = ERRSTR("i2c: received NACK on transmit of data {io}",i2cerr);
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break;
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case 4:
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result = ERRSTR("i2c: unknown error on TwoWire::endTransmission() {io}",i2cerr);
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break;
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case 5:
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result = ERRSTR("i2c: timeout {io}",i2cerr);
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break;
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default:
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result = ERRSTR("i2c: unknown error encounter during I2C transmission {io}",i2cerr);
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}
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}
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// Read and cache response from Notecard
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if (!transmission_error) {
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const int request_length = requested_byte_count_ + NoteI2c::REQUEST_HEADER_SIZE;
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const int response_length = _i2cPort.requestFrom((int)device_address_, request_length);
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if (!response_length) {
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result = ERRSTR("serial-over-i2c: no response to read request {io}",i2cerr);
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} else if (response_length != request_length) {
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result = ERRSTR("serial-over-i2c: unexpected raw byte count {io}",i2cerr);
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} else {
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// Update available with remaining bytes
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*available_ = _i2cPort.read();
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// Ensure protocol response length matches size request
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if (requested_byte_count_ != static_cast<uint8_t>(_i2cPort.read())) {
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result = ERRSTR("serial-over-i2c: unexpected protocol byte count {io}",i2cerr);
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} else {
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for (size_t i = 0 ; i < requested_byte_count_ ; ++i) {
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//TODO: Perf test against indexed buffer writes
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*buffer_++ = _i2cPort.read();
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}
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}
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}
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}
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return result;
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}
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bool
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NoteI2c_Arduino::reset (
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uint16_t device_address_
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) {
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(void)device_address_;
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#if WIRE_HAS_END
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_i2cPort.end();
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#endif
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_i2cPort.begin();
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return true;
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}
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const char *
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NoteI2c_Arduino::transmit (
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uint16_t device_address_,
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uint8_t * buffer_,
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uint16_t size_
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) {
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const char * result = nullptr;
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uint8_t transmission_error = 0;
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_i2cPort.beginTransmission(static_cast<uint8_t>(device_address_));
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_i2cPort.write(static_cast<uint8_t>(size_));
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_i2cPort.write(buffer_, size_);
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transmission_error = _i2cPort.endTransmission();
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if (transmission_error) {
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switch (transmission_error) {
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case 1:
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result = ERRSTR("i2c: data too long to fit in transmit buffer {io}",i2cerr);
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break;
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case 2:
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result = ERRSTR("i2c: received NACK on transmit of address {io}",i2cerr);
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break;
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case 3:
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result = ERRSTR("i2c: received NACK on transmit of data {io}",i2cerr);
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break;
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case 4:
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result = ERRSTR("i2c: unknown error on TwoWire::endTransmission() {io}",i2cerr);
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break;
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case 5:
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result = ERRSTR("i2c: timeout {io}",i2cerr);
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break;
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default:
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result = ERRSTR("i2c: unknown error encounter during I2C transmission {io}",i2cerr);
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}
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}
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return result;
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}

‎src/NoteI2c_Arduino.hpp

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#ifndef NOTE_I2C_ARDUINO_HPP
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#define NOTE_I2C_ARDUINO_HPP
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#include "NoteI2c.hpp"
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#ifndef MOCK
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#include <Wire.h>
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#else
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#include "mock/mock-arduino.hpp"
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#include "mock/mock-parameters.hpp"
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#endif
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class NoteI2c_Arduino final : public NoteI2c {
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public:
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NoteI2c_Arduino(TwoWire & i2c_bus);
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const char * receive(uint16_t device_address, uint8_t * buffer, uint16_t requested_byte_count, uint32_t * available) override;
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bool reset(uint16_t device_address) override;
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const char * transmit(uint16_t device_address, uint8_t * buffer, uint16_t size) override;
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private:
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TwoWire & _i2cPort;
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};
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#endif // NOTE_I2C_ARDUINO_HPP

‎src/NoteSerial_Arduino.cpp

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#include "NoteSerial_Arduino.hpp"
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NoteSerial * make_note_serial (
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NoteSerial *
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make_note_serial (
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NoteSerial::channel_t serial_channel_,
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size_t baud_rate_
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)

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