Firmware/Marlin/twibus.h

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/*
* Marlin 3D Printer Firmware
* Copyright (C) 2016 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
*
* Based on Sprinter and grbl.
* Copyright (C) 2011 Camiel Gubbels / Erik van der Zalm
*
* This program 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.
*
* This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
#ifndef TWIBUS_H
#define TWIBUS_H
#include "macros.h"
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#include <Wire.h>
// Print debug messages with M111 S2 (Uses 236 bytes of PROGMEM)
//#define DEBUG_TWIBUS
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typedef void (*twiSlaveFunc_t)(int bytes);
/**
* TWIBUS class
*
* This class implements a wrapper around the two wire (I2C) bus, it allows
* Marlin to send and request data from any slave device on the bus. This is
* an experimental feature and it's inner workings as well as public facing
* interface are prune to change in the future.
*
* The two main consumers of this class are M155 and M156, where M155 allows
* Marlin to send a I2C packet to a device (please be aware that no repeated
* starts are possible), this can be done in caching method by calling multiple
* times M155 B<byte-1 value in base 10> or a one liner M155, have a look at
* the gcode_M155() function for more information. M156 allows Marlin to
* request data from a device, the received data is then relayed into the serial
* line for host interpretation.
*
*/
class TWIBus {
private:
/**
* @brief Timeout value in milliseconds
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* @details Maximum amount of time (ms) to wait for a reply.
* Useful if something goes wrong on the bus and the
* SDA/SCL lines are held up by another device.
*/
const int timeout = 5;
/**
* @brief Number of bytes on buffer
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* @description Number of bytes in the buffer waiting to be flushed to the bus.
*/
uint8_t buffer_s = 0;
/**
* @brief Internal buffer
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* @details A fixed buffer. TWI commands can be no longer than this.
*/
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char buffer[32];
public:
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/**
* @brief Target device address
* @description The target device address. Persists until changed.
*/
uint8_t addr = 0;
/**
* @brief Class constructor
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* @details Initialize the TWI bus and clear the buffer
*/
TWIBus();
/**
* @brief Reset the buffer
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* @details Set the buffer to a known-empty state
*/
void reset();
/**
* @brief Send the buffer data to the bus
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* @details Flush the buffer to the bus at the target address.
*/
void send();
/**
* @brief Add one byte to the buffer
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* @details Add a byte to the end of the buffer.
* Silently fails if the buffer is full.
*
* @param c a data byte
*/
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void addbyte(const char c);
/**
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* @brief Set the target slave address
* @details The target slave address for sending the full packet.
*
* @param addr 7-bit integer address
*/
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void address(const uint8_t addr);
/**
* @brief Request data from the slave device
* @details Request a number of bytes from a slave device.
* This implementation simply sends the data to serial
* in a parser-friendly format.
*
* @param bytes the number of bytes to request
*/
void reqbytes(const uint8_t bytes);
/**
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* @brief Relay data from the slave device to serial
* @details Relay a number of bytes from the bus to
* serial in a parser-friendly format.
*
* @param bytes the number of bytes to request
*/
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void relaydata(uint8_t bytes);
#if I2C_SLAVE_ADDRESS > 0
/**
* @brief Receive bytes (passively)
* @details Receive bytes sent to our slave address.
* and simply echo them to serial.
*/
inline void receive(uint8_t bytes) { relaydata(bytes); }
/**
* @brief Register a slave handler
* @details Set a handler to receive data from the bus,
* so we can act as a slave.
*
* @param handler A function to handle receiving bytes
*/
inline void onReceive(const twiSlaveFunc_t handler) { Wire.onReceive(handler); }
#endif
#if ENABLED(DEBUG_TWIBUS)
/**
* @brief Prints a debug message
* @details Prints a simple debug message "TWIBus::function: value"
*/
static void debug(const char func[], int32_t val = -1);
#endif
};
#endif //TWIBUS_H