123 lines
3.8 KiB
C++
123 lines
3.8 KiB
C++
/*
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* Marlin 3D Printer Firmware
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* Copyright (C) 2016 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
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*
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* Based on Sprinter and grbl.
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* Copyright (C) 2011 Camiel Gubbels / Erik van der Zalm
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*
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* This program 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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* This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#ifndef TWIBUS_H
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#define TWIBUS_H
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/**
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* TWIBUS class
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*
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* This class implements a wrapper around the two wire (I2C) bus, it allows
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* Marlin to send and request data from any slave device on the bus. This is
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* an experimental feature and it's inner workings as well as public facing
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* interface are prune to change in the future.
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*
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* The two main consumers of this class are M155 and M156, where M155 allows
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* Marlin to send a I2C packet to a device (please be aware that no repeated
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* starts are possible), this can be done in caching method by calling multiple
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* times M155 B<byte-1 value in base 10> or a one liner M155, have a look at
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* the gcode_M155() function for more information. M156 allows Marlin to
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* request data from a device, the received data is then relayed into the serial
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* line for host interpretation.
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*
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*/
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class TWIBus {
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private:
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/**
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* @brief Timeout value in milliseconds
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* @details For blocking operations this constant value will set the max
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* amount of time Marlin will keep waiting for a reply. Useful is something
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* goes wrong on the bus and the SDA/SCL lines are held up by another device.
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*/
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const int timeout = 5;
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/**
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* @brief Target device address
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* @description This stores, until the buffer is flushed, the target device
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* address, take not we do follow Arduino 7bit addressing.
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*/
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uint8_t addr = 0;
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/**
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* @brief Number of bytes on buffer
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* @description This var holds the total number of bytes on our buffer
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* waiting to be flushed to the bus.
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*/
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uint8_t buffer_s = 0;
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/**
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* @brief Internal buffer
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* @details This is a fixed buffer, TWI command cannot be longer than this
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*/
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char buffer[30];
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public:
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/**
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* @brief Class constructor
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* @details Initialized the TWI bus and clears the buffer
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*/
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TWIBus();
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/**
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* @brief Reset the buffer
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* @details Brings the internal buffer to a known-empty state
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*/
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void reset();
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/**
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* @brief Send the buffer data to the bus
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* @details Flushed the buffer into the bus targeting the cached slave device
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* address.
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*/
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void send();
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/**
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* @brief Add one byte to the buffer
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* @details Adds the byte to the buffer in a sequential way, if buffer is full
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* the request is silently ignored.
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*
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* @param c a data byte
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*/
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void addbyte(char c);
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/**
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* @brief Sets the target slave address
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* @details The target slave address is stored so it can be later used when
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* the complete packet needs to be sent over the bus.
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*
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* @param addr 7-bit integer address
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*/
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void address(uint8_t addr);
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/**
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* @brief Request data from slave device
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* @details Requests data from a slave device, when the data is received it will
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* be relayed to the serial line using a parser-friendly formatting.
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*
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* @param bytes the number of bytes to request
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*/
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void reqbytes(uint8_t bytes);
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};
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#endif //TWIBUS_H
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