neu-implementierung. Funktioniert einigermaßen, interferiert aber mit anderen timer-basierten bibliotheken

Signed-off-by: Stephan Richter <s.richter@srsoftware.de>

README.md

@@ -0,0 +1,12 @@
+# Library to interact with RS485 serial
+
+Ist im Moment so implementiert, dass ein timer läuft und der Bus permanent überwacht wird.
+
+Funktioniert einigermaßen, interferiert aber mit anderen Libs, die Timer benutzen.
+
+Also doch nochmal neu schreiben, so dass
+
+* zum Lesen Flanken erkannt und Zeiten zwischen diesen interpretiert werden
+* das Schreiben timer-basiert erfolgt
+
+Zur Orientierung kann das alte Protokoll, wie es noch beim Controllino verwendet wird, herangezogen werden

SoftRS485.cpp

@@ -7,121 +7,138 @@
 #include "SoftRS485.h"
 
 //#define DEBUG
-#define IDLE -1
-#define START -2
 #define MSG_LEN 64
 
+#define IDLE 0
+#define START 1
+#define RECEIVING 2
+#define SENDING 3
+#define COMPLETE 4
+
+// Pins
 int _RO, _RE, _DE, _DI;
+int _idle_cycles = 0;
 
 /* INCOMING */
-byte _recv_byte = 0x0;
+char    _recv_message[MSG_LEN];
+byte    _recv_byte = 0x00;
+byte    _recv_state = IDLE;
 boolean _recv_bit = false;
-char _recv_message[MSG_LEN];
-int _recv_idx = 0; // used as bit-index for _recv_byte
-int _recv_pos = IDLE; // used as char-index for _recv_message
+byte    _recv_idx = 0;
+int     _recv_pos = 0;
+
+
 
 /* OUTGOING */
-char _message_out[MSG_LEN];
-int _send_pos = IDLE;
-int _send_idx = 0;
+char _send_message[MSG_LEN];
+boolean _send_bit = false;
+byte _send_state = IDLE;
+byte _send_wait = 0;
+byte _send_idx = 0;
+int  _send_pos = 0;
 
 ISR(TIMER1_COMPA_vect){
-    OCR1A += 62500; // Advance The COMPA Register
+    OCR1A += 3228; // Advance The COMPA Register
 
-    _recv_bit = !digitalRead(_RO); // input line is HIGH by default
-    if (_recv_pos == IDLE){
-        if (_recv_bit) { // first 1 indicates incoming message
-            _recv_pos = 0;
+    if (_send_state == SENDING){
+        char c = _send_message[_send_pos];
+        _send_bit = c & 1<<_send_idx;
+        digitalWrite(_DI,!_send_bit);
 #ifdef DEBUG
-            Serial.println(F("start of message reception"));
+        Serial.print("Sending bit "); Serial.print(_send_idx); Serial.print(" of "); Serial.print(c); Serial.print(": "); Serial.print(_send_bit); Serial.print(" / ");
 #endif
+        _send_idx++;
+        if (_send_idx==8){ // byte completed
+            _send_pos++;  // advance to next byte
+            _send_idx = 0; // start with first bit
+            if (c == 0x00 || _send_idx == MSG_LEN){ // we just send a 0-byte
+                _send_state = COMPLETE;
+            }
         }
-    } else { // we are reading!
-        _recv_byte |= _recv_bit << _recv_idx;
-#ifdef DEBUG
-        Serial.print(F("received bit #"));
-        Serial.print(_recv_idx);
-        Serial.print(": ");
-        Serial.println(_recv_bit);
-        Serial.print(F("byte is now "));
-        Serial.println(_recv_byte,BIN);
-#endif
-        if (_recv_idx == 7){ // byte complete
-#ifdef DEBUG
-            Serial.print(F("byte complete: "));
-            Serial.println(_recv_byte);
-#endif
-            _recv_idx = 0;
-            _recv_message[_recv_pos] = _recv_byte;
-            if (_recv_byte == 0x00){ // we encountered a 0-byte! End of message!
+    }
+    if (_send_state == START && _idle_cycles > 9){
+        _send_bit = HIGH;
+        digitalWrite(_DE,HIGH);
+        digitalWrite(_DI,!_send_bit);
+        _send_state = SENDING;
+        _send_idx = 0;
+        _send_pos = 0;
 #ifdef DEBUG
-                Serial.print(F("got 0-byte!\nmessage reception complete: "));
-                Serial.println(_recv_message);
+        Serial.print("Sent start bit: "); Serial.print(_send_bit); Serial.print(" / ");
 #endif
-                _recv_idx = 0;
-                _recv_pos = IDLE;
-            } else {
-                _recv_byte = 0x00;
-                if (_recv_pos<MSG_LEN-1) {
-                    _recv_pos++;
-                }
-            }
-        } else _recv_idx++;
     }
 
-    boolean bit = LOW;
+    _recv_bit = !digitalRead(_RO); // LOW = 1
 
-    if (_send_pos >= 0){
-        char c = _message_out[_send_pos];
-        if (c == 0x00) { // end of message
-            digitalWrite(_DI,HIGH);
-            digitalWrite(_DE,LOW);
-            _send_pos = IDLE;
-            _send_idx = 0;
-            _message_out[0] = 0x00;
+    if (_recv_bit) {
+        _idle_cycles = 0;
+    } else if (_idle_cycles<1000) {
+        _idle_cycles++;
+    }
 #ifdef DEBUG
-            Serial.println("Message transmission completed!");
+    Serial.print("idle cycles: "); Serial.print(_idle_cycles); Serial.print(" / ");
+    Serial.print("received: "); Serial.print(_recv_bit); Serial.print(" / ");
 #endif
-        } else {
-            bit = !(c & 1<<_send_idx);
-            digitalWrite(_DI,bit);
+
+    if (_send_bit != _recv_bit && _send_state == SENDING){ // collision while sending
+        digitalWrite(_DE,LOW); // disable driver
+        _send_state = START;   // start over
+        _idle_cycles = 0;
 #ifdef DEBUG
-            Serial.print("Sending bit #");
-            Serial.print(_send_idx);
-            Serial.print(" (");
-            Serial.print(bit);
-            Serial.print(") of ");
-            Serial.print(c);
-            Serial.print(" (");
-            Serial.print(c,BIN);
-            Serial.println(")");
+        Serial.println("\nCOLLISION");
 #endif
-            _send_idx++;
-            if (_send_idx>7){
-                _send_idx =0;
-                _send_pos++;
-            }
-        }
     }
 
-    if (_send_pos == START && _recv_pos == IDLE && _message_out[0] != 0x00) { // outgoig message awaits, line is idle
-        digitalWrite(_DE,HIGH); // enable driver
+    if (_send_state == COMPLETE){
+        digitalWrite(_DE,LOW); // disable driver
+        _send_message[0]=0x00; // clear message
+        _send_state = IDLE;
+        _idle_cycles =0;
 #ifdef DEBUG
-        Serial.println(F("starting transmission"));
+        Serial.print("transmission complete / ");
 #endif
-        digitalWrite(_DI,bit); // send start bit
-        _send_pos = 0;
     }
 
-    if (_send_pos != IDLE && digitalRead(_RO) != bit){ // driver output state mismatch!
-        digitalWrite(_DE,LOW); // disable driver
-        _send_pos = START;
+
+
+    if (_recv_state == START){
+        _recv_byte = 0x00;
+        _recv_pos = 0;
+        _recv_idx = 0;
+        _recv_state = RECEIVING;
 #ifdef DEBUG
-        Serial.println(F("collision!"));
+        Serial.print("Start reception / ");
 #endif
     }
 
+    if (_recv_bit && _recv_state == IDLE){
+        _recv_state = START;
+    }
+
+    if (_recv_state == RECEIVING){
+        _recv_byte |= _recv_bit << _recv_idx;           // set bit
+        _recv_idx++;                                    // increase bit index
+        if (_recv_idx == 8){                            // byte full
+#ifdef DEBUG
+            Serial.print("pushing "); Serial.print((char)_recv_byte); Serial.print(" / ");
+#endif
 
+            _recv_message[_recv_pos] = _recv_byte;      // push character to string
+            if (_recv_byte == 0x00) {                   // end of message
+                _recv_state = IDLE;
+#ifdef DEBUG
+                Serial.print("reception complete: "); Serial.print(_recv_message);
+#endif
+            }
+            _recv_idx=0;                                // start new byte
+            _recv_byte = 0;
+            _recv_pos++;                                // goto next string pos
+            if (_recv_pos == MSG_LEN) _recv_pos--;      // avoid overflow
+        }
+    }
+#ifdef DEBUG
+    Serial.println();
+#endif
 }
 
 void init485(int RO, int nRE, int DE, int DI){
@@ -130,7 +147,7 @@ void init485(int RO, int nRE, int DE, int DI){
     _DE=DE;
     _DI=DI;
     _recv_message[0] = 0x00; // empty
-    _message_out[0] = 0x00; // empty
+    _send_message[0] = 0x00; // empty
     pinMode(_RO,INPUT);
 
     pinMode(_RE,OUTPUT);
@@ -144,8 +161,8 @@ void init485(int RO, int nRE, int DE, int DI){
 
     TCCR1A = 0;           // Init Timer1A
     TCCR1B = 0;           // Init Timer1B
-    TCCR1B |= B00000001;  // Prescaler = 512
-    OCR1A = 500;        // Timer Compare1A Register
+    TCCR1B |= B00000001;  // Prescaler = 1
+    OCR1A = 3328;        // Timer Compare1A Register
     TIMSK1 |= B00000010;  // Enable Timer COMPA Interrupt
 #ifdef DEBUG
     Serial.begin(115200);
@@ -162,7 +179,7 @@ void init485(int RO, int nRE, int DE, int DI){
 }
 
 boolean available485(){
-    return _recv_pos == IDLE && _recv_message[0] != 0;
+    return _recv_state == IDLE && _recv_message[0] != 0;
 }
 
 String get485Message(){
@@ -172,17 +189,16 @@ String get485Message(){
 }
 
 boolean send485(char message[]){
-    if (_message_out[0] != 0x00) return false; // we already have a queued message, abort!
+    if (_send_message[0] != 0x00) return false; // we already have a queued message, abort!
     for (int idx = 0; idx<MSG_LEN; idx++){
-        _message_out[idx] = message[idx]; // copy message
+        _send_message[idx] = message[idx]; // copy message
         if (message[idx] == 0x00) break;
     }
-    if (_message_out[0] == 0x00) return false; // message is empty! abort
-    _send_pos = START;
+    if (_send_message[0] == 0x00) return false; // message is empty! abort
+    _send_state = START;
 
 #ifdef DEBUG
-    Serial.print("sending ");
-    Serial.println(_message_out);
+    Serial.print("sending "); Serial.println(_send_message);
 #endif
     return true;
 }

examples/ReceiveDemo/ReceiveDemo.ino

@@ -0,0 +1,24 @@
+/*
+ This sketch demonstrates, how to use the SoftRS485 library.
+ This library makes use of Arduinos timer 1
+ */
+
+#include <SoftRS485.h>
+
+void setup() {
+  Serial.begin(115200);
+
+  init485(2,3,4,5); // library initialization:
+  // connect pin 2 to RO of Max485
+  // connect pin 3 to ^RE of Max485
+  // connect pin 4 to DE of Max485
+  // connect pin 5 to DI of Max485
+
+}
+
+void loop(){
+  if (available485()){ // check if we have received anything
+    Serial.print("messageReceived: ");
+    Serial.println(get485Message()); // read the received message
+  }
+}

examples/SendAndReceive/SendAndReceive.ino

@@ -27,9 +27,6 @@ void setup() {
   }
 }
 
-void messageReceived(String message){
-}
-
 void loop(){
   if (available485()){ // check if we have received anything
     Serial.print("messageReceived: ");
@@ -39,6 +36,10 @@ void loop(){
     count++;
     char msg[128];
     (message+count).toCharArray(msg,128);
-    send485(msg);
+    if (!send485(msg)){
+      Serial.print("Sending ");
+      Serial.print(msg);
+      Serial.println(" failed!");
+    }
   }
 }

examples/SendButton/SendButton.ino

@@ -0,0 +1,33 @@
+/*
+ This sketch demonstrates, how to use the SoftRS485 library.
+ This library makes use of Arduinos timer 1
+ */
+
+#include <SoftRS485.h>
+
+const int buttonPin = 10;     // the number of the pushbutton pin
+boolean button_state = true;
+
+void setup() {
+  Serial.begin(115200);
+
+  init485(2,3,4,5); // library initialization:
+  // connect pin 2 to RO of Max485
+  // connect pin 3 to ^RE of Max485
+  // connect pin 4 to DE of Max485
+  // connect pin 5 to DI of Max485
+
+  pinMode(buttonPin, INPUT_PULLUP);
+}
+
+void loop(){
+  boolean new_state = digitalRead(buttonPin);
+  if (new_state != button_state){
+    button_state = new_state;
+    if (new_state == LOW){
+      send485("Button pressed");
+    } else {
+      send485("Button released");
+    }
+  }
+}