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‎README.md‎

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# LIN-Transceiver-Library (TJA1020)
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Extends the Lin-Interface class and ensure the TJA1020 statemachine will be served in the correct way
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example:
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#include "TJA1020.h"
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#define LIN_SERIAL_SPEED 19200
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#define lin_NSLP_Pin 32
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// RX and TX Pin is defined per UART_nr
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TJA1020 LinBus(2, LIN_SERIAL_SPEED, lin_NSLP_Pin); // UART_nr, Baudrate, /SLP-Pin
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void setup()
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{
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}
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void loop()
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{
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uint8_t data = 0x00;
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// Read Frame FID = 0x20
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if (LinBus.readFrame(0x20))
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{
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// Read succesfull
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data = LinBus.LinMessage[0];
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}
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// let LIN-Tranceiver sleep
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LinBus.setMode(LinBus.Sleep);
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}

‎library.json‎

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{
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"name": "Lin-Transceiver",
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"version": "0.0.1",
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"description": "utilizes a LIN Transceiver TJA1020: Sleep / NormalSlope / LowSlope",
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"keywords": [
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"TJA1020",
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"LIN",
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"Lin-Bus"
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],
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"repository": {
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"type": "git",
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"url": "https://github.com/mestrode/Lin-Transceiver-Library"
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},
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"authors": [
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{
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"name": "mestrode",
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"maintainer": true
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}
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],
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"license": "GPL-2.0-only",
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"dependencies": [
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{
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"name": "LIN-Interface",
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"version": "https://github.com/mestrode/LIN-Interface-Library.git"
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}
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]
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}

‎library.properties‎

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name=Lin-Transceiver
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version=0.0.1
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author=mestrode <[email protected]>
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maintainer=mestrode <[email protected]>
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sentence=provides Lin-Interface via TJA1020
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paragraph=provides Lin-Interface via TJA1020, therefore the statemachine within the TJA1020 is considered by read and write operations
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category=Communication
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url=https://github.com/mestrode/Lin-Transceiver-Library
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architectures=*
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depends=Lin-Interface
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includes=TJA1020.hpp
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license=GPL-2.0-only

‎src/TJA1020.cpp‎

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// Utilizes a TJA1020 Lin-Transceiver
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// Provides Lin-Interface but considers the statemachin in all steps
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//
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// Copyright mestrode <[email protected]>
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// Original Source: "https://github.com/mestrode/Lin-Transceiver-Library"
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//
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// Requires class Lin_Interface: https://github.com/mestrode/Lin-Interface-Library
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//
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// Tested with ESP32
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#include "TJA1020.hpp"
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#include <Lin-Interface.h>
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// #include <Arduino.h>
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//-----------------------------------------------------------------------------
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// Pin definitions, we need the TX Pin to control the TJA1020 statemachine
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// See "HardwareSerial.cpp"
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#ifdef ESP32
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#ifndef TX0
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#define TX0 1
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#endif
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#ifndef TX1
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#define TX1 10
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#endif
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#ifndef TX2
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#define TX2 17
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#endif
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#else
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#error "Need Pin definitions for LIN Transceiver"
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#endif
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//-----------------------------------------------------------------------------
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// constructor
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/// Provides HW UART via TJA1020 Chip
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Lin_TJA1020::Lin_TJA1020(int uart_nr, uint32_t _baud, int8_t nslpPin) : Lin_Interface(uart_nr)
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{
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// Use typical pin configuration if interfaced by uart_nr
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//############
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// See "HardwareSerial.cpp"
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if(uart_nr == 0) {
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_tx_pin = TX0;
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}
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if(uart_nr == 1) {
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_tx_pin = TX1;
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}
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if(uart_nr == 2) {
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_tx_pin = TX2;
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}
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//############
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// use default baud rate, if not specified
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Lin_Interface::baud = _baud ? _baud : 19200;
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_nslp_pin = nslpPin;
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}
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//-----------------------------------------------------------------------------
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// write / read on bus
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/// Requests a Lin 2.0 Frame
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bool Lin_TJA1020::readFrame(uint8_t FrameID)
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{
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setMode(_writingSlope);
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return Lin_Interface::readFrame(FrameID);
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}
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/// Sends a Lin 2.0 Frame
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void Lin_TJA1020::writeFrame(uint8_t FrameID, size_t size)
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{
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setMode(_writingSlope);
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return Lin_Interface::writeFrame(FrameID, size);
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}
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/// Sends a Lin 1.3 Frame (Legacy Checksum)
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void Lin_TJA1020::writeFrameClassic(uint8_t FrameID, size_t size)
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{
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setMode(_writingSlope);
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Lin_Interface::writeFrameClassic(FrameID, size);
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}
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/// does control sequences to switch from one to another operational mode of the chip
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/// NormalSlope, LowSlope for writing operation;
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/// Sleep will release INH and may disables Power-Supply
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/// @param newMode TJA1020 Mode to be the next
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void Lin_TJA1020::setMode(TJA1020_Mode mode)
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{
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// we don't need to act, if we're allready there
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// see "setMode(sleep)" in the switch below
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if (mode == _currentMode)
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{
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break;
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}
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pinMode(_tx_pin, OUTPUT); // TX Signal to LIN Tranceiver
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pinMode(_nslp_pin, OUTPUT); // /SLP Signal to LIN Tranceiver
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// Statemachine des TJA1020 von [SLEEP] nach [NORMAL SLOPE MODE] ändern
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switch (mode)
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{
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case NormalSlope:
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if (_currentMode == LowSlope)
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{
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// no direct step from LowSlope to NormalSlope
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setMode(Sleep);
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}
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// rising edge on /SLP while TXD = 1
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digitalWrite(_tx_pin, HIGH);
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delayMicroseconds(10); // ensure signal to settle
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// create rising edge
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digitalWrite(_nslp_pin, LOW);
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delayMicroseconds(15); // ensure t_gotosleep (min. 10us)
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digitalWrite(_nslp_pin, HIGH);
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delayMicroseconds(15); // ensure t_gotonorm (min. 10us)
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// [Normal Slope Mode] reached
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_currentMode = NormalSlope;
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break;
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case LowSlope:
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if (_currentMode == NormalSlope)
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{
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// no direct step from NormalSlope to LowSlope
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setMode(Sleep);
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}
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// rising edge on /SLP while TXD = 0
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digitalWrite(_tx_pin, LOW);
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delayMicroseconds(10); // ensure signal to settle
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// create rising edge
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digitalWrite(_nslp_pin, LOW);
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delayMicroseconds(15); // ensure t_gotosleep (min. 10us)
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digitalWrite(_nslp_pin, HIGH);
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delayMicroseconds(15); // ensure t_gotonorm (min. 10us)
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// [Low Slope Mode] reached
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_currentMode = LowSlope;
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break;
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default: // = Sleep
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// no direct step from Standby to Sleep, but we don't know if we're in
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// we're going over _writingSlope
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setMode(_writingSlope);
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// rising edge on /SLP while TXD = 1
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digitalWrite(_tx_pin, HIGH);
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delayMicroseconds(10); // ensure signal to settle
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// create falling edge
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digitalWrite(_nslp_pin, HIGH);
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delayMicroseconds(15); // ensure t_gotosleep (min. 10us)
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digitalWrite(_nslp_pin, LOW);
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delayMicroseconds(15); // ensure t_gotonorm (min. 10us)
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break;
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// [Sleep] reached
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_currentMode = Sleep;
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}
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} // void Lin_TJA1020::setMode(TJA1020_Mode newMode)
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/// Defines standard slope, to be used, when writing to the bus
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void Lin_TJA1020::setSlope(TJA1020_Mode slope) {
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_writingSlope = slope;
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if (_writingSlope == Sleep) {
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_writingSlope = NormalSlope;
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}
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}

‎src/TJA1020.hpp‎

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// Utilizes a TJA1020 Lin-Transceiver
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// Provides Lin-Interface but considers the statemachin in all steps
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//
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// Copyright mestrode <[email protected]>
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// Original Source: "https://github.com/mestrode/Lin-Transceiver-Library"
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//
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// Requires class Lin_Interface: https://github.com/mestrode/Lin-Interface-Library
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//
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// Tested with ESP32
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#pragma once
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// #include <Arduino.h>
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#include <Lin-Interface.hpp>
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class Lin_TJA1020 : public Lin_Interface
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{
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public:
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enum TJA1020_Mode { Sleep, NormalSlope, LowSlope };
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/// provides HW-Lin Interface via TJA1020 Chip
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/// @param uart_nr Index of HW UART to be used (0..2)
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/// @param baud Baud rate for RX/TX (0 = default 19200 baud)
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/// @param nslpPin /SLP Pin to control TJA1020
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Lin_TJA1020(int uart_nr, uint32_t _baud, int8_t nslpPin);
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bool readFrame(uint8_t FrameID);
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void writeFrame(uint8_t FrameID, size_t size);
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void writeFrameClassic(uint8_t FrameID, size_t size);
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/// returns the current mode of TJA1020 chip
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TJA1020_Mode getMode();
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/// switches the operational mode of TJA1020 chip
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/// @param mode target mode
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void setMode(TJA1020_Mode mode);
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/// Defines standard slope rate, when using to the bus
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/// @param slope "NormalSlope" or "LowSlope" is only valid
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void setSlope(TJA1020_Mode slope);
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private:
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TJA1020_Mode _writingSlope = NormalSlope;
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TJA1020_Mode _currentMode = Sleep;
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int8_t _tx_pin;
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int8_t _nslp_pin;
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};

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