Stephan Richter
12 months ago
3 changed files with 184 additions and 0 deletions
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/* RS 485-Implementierung, die sowohl Schreiben als auch Lesen kann */ |
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/* Basis für andere Projekte */ |
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#define BUTTON 2 |
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#define RECEIVE 3 |
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#define RECEIVE_ENABLE 4 |
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#define SEND 5 |
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#define SEND_ENABLE 6 |
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#define MAX_LEN 128 |
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void setup() { |
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// Buttons connected to analog input lines
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pinMode(A0,INPUT_PULLUP); |
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pinMode(A1,INPUT_PULLUP); |
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pinMode(A2,INPUT_PULLUP); |
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pinMode(A3,INPUT_PULLUP); |
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pinMode(A4,INPUT_PULLUP); |
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pinMode(A5,INPUT_PULLUP); |
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pinMode(A6,INPUT_PULLUP); |
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pinMode(A7,INPUT_PULLUP); |
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// Currently, all buttons are also connected via a diode to an interruptable pin, to notify on input changes.
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// This interruptable pin should be assgined to BUTTON
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pinMode(BUTTON,INPUT_PULLUP); |
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attachInterrupt(digitalPinToInterrupt(BUTTON),button,FALLING); // interrupt for button change
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// Set up pins for RS485 connection
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pinMode(RECEIVE, INPUT); |
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pinMode(RECEIVE_ENABLE, OUTPUT); |
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pinMode(SEND, OUTPUT); |
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pinMode(SEND_ENABLE, OUTPUT); |
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attachInterrupt(digitalPinToInterrupt(RECEIVE),receive,CHANGE); // interrupt for incoming RS485 traffic
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reset485(); |
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buttons = 0x0; |
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} |
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void button() { |
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buttons = 0xFF ^ (digitalRead(A7)<<7 | digitalRead(A6)<<6 | digitalRead(A5)<<5 | digitalRead(A4)<<4 | digitalRead(A3)<<3 | (!digitalRead(A2))<<2 | digitalRead(A1)<<1 | digitalRead(A0));
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} |
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void receive(){ |
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bool received_bit = digitalRead(RECEIVE); |
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curr = micros(); |
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duration = curr - last; |
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Serial.print("Input switched to "); |
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Serial.print(received_bit?"H":"L");
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Serial.print(" after "); |
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Serial.print(duration); |
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Serial.println(" ticks"); |
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last = curr; |
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if (duration > MAX_TICKS) reset485(); |
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received_bit = !received_bit; // received_bit is the current value, the duration of the previous value (=inverted) has been measured
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duration /= BASE; |
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while (duration > 0){ |
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byte_idx--; |
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recv |= received_bit<<byte_idx; |
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if (byte_idx == 0) { |
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msg[msg_idx] = recv; |
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msg_idx++; |
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byte_idx = 8; |
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if (recv == 0x00) message_received(); |
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} |
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duration--; |
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} |
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} |
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void reset485(){ |
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byte_idx = 8; |
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msg_idx = 0; |
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recv=0x0; |
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} |
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void message_received(){ |
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for (int i=0; i<MAX_LEN; i++) message[i]=msg[i]; |
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reset485(); |
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} |
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void button_pressed(int i){ |
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Serial.println("not implemented"); |
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} |
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void loop(){ |
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if (buttons>0){ |
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for (int i=0; i<7; i++){ |
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if (buttons & (1<<i)) button_pressed(i);
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}
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} |
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if (message[0] != 0x0){ |
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Serial.print("Received '"); |
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Serial.print(message); |
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Serial.println("'");
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message[0] = 0x0; |
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} |
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} |
@ -0,0 +1,85 @@ |
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/*// This sketch allows manual setting of the RS485-connected pins via serial terminal commands
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Commands are: |
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r+ – enable read mode (^RE ← LOW) |
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r- – disable read mode (^RE ← HIGH) |
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w+ – enable write mode (DE ← HIGH) |
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w- – disable write mode (DE ← LOW) |
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h – send HIGH level on DI |
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l – send LOW level on DI |
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//*/
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#if defined(ARDUINO_AVR_UNO) |
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#define RS485_RO 5 |
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#define RS485_RE 4 |
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#define RS485_DE 3 |
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#define RS485_DI 2 |
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#define BOARD "Arduino Uno" |
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#endif |
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#if defined(ARDUINO_AVR_NANO) |
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#define RS485_RO 3 |
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#define RS485_RE 2 |
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#define RS485_DE 4 |
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#define RS485_DI 5 |
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#define BOARD "Arduino Nano" |
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#endif |
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String command = ""; |
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bool doPrint = false; |
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// the setup function runs once when you press reset or power the board
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void setup() { |
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// initialize digital pin LED_BUILTIN as an output.
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pinMode(RS485_RO, INPUT); |
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pinMode(RS485_RE, OUTPUT); |
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pinMode(RS485_DE, OUTPUT); |
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pinMode(RS485_DI, OUTPUT); |
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digitalWrite(RS485_RE,LOW); |
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digitalWrite(RS485_DE,LOW); |
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digitalWrite(RS485_DI,LOW); |
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Serial.begin(115200); |
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Serial.println(F("this is Projekte/Arduino/MAX485/ManualSend")); |
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Serial.println(F("send any of the followning commands:")); |
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Serial.println(F("- r+ (enable read)\n- r- (disable read)\n- w+ (enable write)\n- w- (disable write)\n- h (for high)\n- l (for low)")); |
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} |
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// the loop function runs over and over again forever
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void loop() { |
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while (Serial.available()){ |
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char inChar = (char)Serial.read(); |
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if (inChar == '\n') { |
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process(command); |
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command = "";
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doPrint = true; |
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} else { |
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command += inChar; |
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} |
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} |
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if (doPrint){ |
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printState(); |
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delay(1000); |
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} |
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} |
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void printState(){ |
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Serial.print("RE = "); |
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Serial.print(1-digitalRead(RS485_RE)); |
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Serial.print(", DE = "); |
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Serial.print(digitalRead(RS485_DE)); |
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Serial.print(", DI = "); |
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Serial.print(digitalRead(RS485_DI)); |
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Serial.print(", RO = "); |
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Serial.println(digitalRead(RS485_RO)); |
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} |
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void process(String command){ |
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Serial.print(F("received:")); |
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Serial.println(command); |
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if (command == "r+") digitalWrite(RS485_RE,LOW); |
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if (command == "r-") digitalWrite(RS485_RE,HIGH); |
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if (command == "w+") digitalWrite(RS485_DE,HIGH); |
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if (command == "w-") digitalWrite(RS485_DE,LOW); |
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if (command == "h") digitalWrite(RS485_DI,HIGH); |
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if (command == "l") digitalWrite(RS485_DI,LOW); |
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printState(); |
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} |
@ -0,0 +1,4 @@ |
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Erkenntnisse: |
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1. Wenn alle Treiber inaktiv sind, also bei allen Teilnehmer DI = Low ist, kommt vom RO ein High-Signal |
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2. das High-Signal ist dominant, d.h. wenn mehrere Teilnehmer senden, und mindestens ein Teilnehmer eine 1 auf den Bus legt, erhalten alle am RO einen HIGH-Pegel |
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