StephanRichter
/
SoftRS485
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity
Browse Source

re-implemented library. needs to be tested! 

Signed-off-by: Stephan Richter <s.richter@srsoftware.de>
main
Stephan Richter 1 year ago
parent
8a1b4685da
commit
78c1f77b87
3 changed files with 116 additions and 182 deletions
Whitespace
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Split View
Diff Options
Show Stats Download Patch File Download Diff File
  1. 244
      SoftRS485.cpp
  2. 3
      SoftRS485.h
  3. 45
      examples/SendAndReceive/SendAndReceive.ino

244
SoftRS485.cpp
Unescape View File

@ -9,136 +9,50 @@ @@ -9,136 +9,50 @@
//#define DEBUG
#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;
long _pulse_len = 100;
/* INCOMING */
char _recv_message[MSG_LEN];
byte _recv_byte = 0x00;
byte _recv_state = IDLE;
// Receive vars
boolean _recv_bit = false;
byte _recv_idx = 0;
long _last_flip; // this is the time when the bus switched to logical zero
byte _recv_msg[MSG_LEN];
int _recv_pos = 0;
/* OUTGOING */
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 += 3228; // Advance The COMPA Register
if (_send_state == SENDING){
char c = _send_message[_send_pos];
_send_bit = c & 1<<_send_idx;
digitalWrite(_DI,!_send_bit);
#ifdef DEBUG
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;
}
}
}
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;
int _recv_idx = 0;
boolean _avail = false;
void interrupt485(){
_recv_bit = !digitalRead(_RO); // HIGH level = logical zero and vice versa
long now = micros();
long diff = now - _last_flip;
_last_flip = now;
if (diff > 20*_pulse_len){ // we received a start bit
#ifdef DEBUG
Serial.print("Sent start bit: "); Serial.print(_send_bit); Serial.print(" / ");
Serial.print(F("State changed to ")); Serial.println(_recv_bit);
Serial.println(F("received start bit"));
#endif
}
_recv_bit = !digitalRead(_RO); // LOW = 1
if (_recv_bit) {
_idle_cycles = 0;
} else if (_idle_cycles<1000) {
_idle_cycles++;
}
#ifdef DEBUG
Serial.print("idle cycles: "); Serial.print(_idle_cycles); Serial.print(" / ");
Serial.print("received: "); Serial.print(_recv_bit); Serial.print(" / ");
#endif
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.println("\nCOLLISION");
#endif
}
if (_send_state == COMPLETE){
digitalWrite(_DE,LOW); // disable driver
_send_message[0]=0x00; // clear message
_send_state = IDLE;
_idle_cycles =0;
#ifdef DEBUG
Serial.print("transmission complete / ");
#endif
}
if (_recv_state == START){
_recv_byte = 0x00;
_recv_pos = 0;
_recv_idx = 0;
_recv_state = RECEIVING;
#ifdef DEBUG
Serial.print("Start reception / ");
#endif
_last_flip+=_pulse_len;
} else {
long count = diff/_pulse_len;
for (int i=0; i<count; i++){
if (_recv_idx == 0) {
_recv_msg[_recv_pos] = (!_recv_bit);
} else {
_recv_msg[_recv_pos] |= (!_recv_bit)<<_recv_idx;
}
if (_recv_bit && _recv_state == IDLE){
_recv_state = START;
_recv_idx++;
if (_recv_idx == 8){
_recv_idx = 0;
if (_recv_msg[_recv_pos] == 0x00){
_avail = _recv_pos != 0;
return;
}
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_pos++;
}
_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){
@ -146,8 +60,7 @@ void init485(int RO, int nRE, int DE, int DI){ @@ -146,8 +60,7 @@ void init485(int RO, int nRE, int DE, int DI){
_RE=nRE;
_DE=DE;
_DI=DI;
_recv_message[0] = 0x00; // empty
_send_message[0] = 0x00; // empty
pinMode(_RO,INPUT);
pinMode(_RE,OUTPUT);
@ -159,46 +72,93 @@ void init485(int RO, int nRE, int DE, int DI){ @@ -159,46 +72,93 @@ void init485(int RO, int nRE, int DE, int DI){
pinMode(_DI,OUTPUT);
digitalWrite(_DI,LOW); // output line = LOW
TCCR1A = 0; // Init Timer1A
TCCR1B = 0; // Init Timer1B
TCCR1B |= B00000001; // Prescaler = 1
OCR1A = 3328; // Timer Compare1A Register
TIMSK1 |= B00000010; // Enable Timer COMPA Interrupt
attachInterrupt(digitalPinToInterrupt(_RO),interrupt485,CHANGE);
#ifdef DEBUG
Serial.begin(115200);
Serial.println("Started timer!");
Serial.print("RO = ");
Serial.print(F("RO = "));
Serial.println(_RO);
Serial.print("^RE = ");
Serial.print(F("^RE = "));
Serial.println(_RE);
Serial.print("DE = ");
Serial.print(F("DE = "));
Serial.println(_DE);
Serial.print("DI = ");
Serial.print(F("DI = "));
Serial.println(_DI);
#endif
_last_flip = micros();
}
void speed485(long baudrate){
#ifndef DEBUG
_pulse_len = 1e6 / baudrate;
#else
_pulse_len = 1000;
Serial.print(F("Set pulse_len to ")); Serial.print(_pulse_len); Serial.println(F("µs"));
#endif
}
boolean available485(){
return _recv_state == IDLE && _recv_message[0] != 0;
return _avail;
}
String get485Message(){
String res = String(_recv_message);
_recv_message[0] = 0;
return res;
String get485message(){
_avail = false;
return String((char*)_recv_msg);
}
boolean send485(char message[]){
if (_send_message[0] != 0x00) return false; // we already have a queued message, abort!
for (int idx = 0; idx<MSG_LEN; idx++){
_send_message[idx] = message[idx]; // copy message
if (message[idx] == 0x00) break;
boolean writeBit(boolean bit){
digitalWrite(_DI,!bit);
delayMicroseconds(5);
if (_recv_bit != bit){ // collision!
digitalWrite(_DE,LOW);
#ifdef DEBUG
Serial.println(F("Collision!"));
#endif
return false;
}
if (_send_message[0] == 0x00) return false; // message is empty! abort
_send_state = START;
delayMicroseconds(_pulse_len-5);
return true;
}
boolean send485(char message[]){
#ifdef DEBUG
Serial.print("sending "); Serial.println(_send_message);
Serial.print(F("preparing to send "));
Serial.print(message);
Serial.print(F(": line state = "));
Serial.print(_recv_bit);
Serial.print(F(" / last_flip = "));
Serial.print(_last_flip);
Serial.print(F(" / micros = "));
Serial.println(micros());
#endif
return true;
while (_recv_bit || (micros() - _last_flip) < (20 * _pulse_len)) {
delayMicroseconds(20*_pulse_len);
}
#ifdef DEBUG
Serial.println(F("enabling driver…"));
#endif
digitalWrite(_DE,HIGH); // enable driver
if (!writeBit(HIGH)) return false;
int pos = -1;
boolean good = true;
do {
pos++;
#ifdef DEBUG
Serial.print(F("sending character ")); Serial.println(message[pos]);
#endif
good = writeBit(message[pos] & 0x01)
&& writeBit(message[pos] & 0x02)
&& writeBit(message[pos] & 0x04)
&& writeBit(message[pos] & 0x08)
&& writeBit(message[pos] & 0x10)
&& writeBit(message[pos] & 0x20)
&& writeBit(message[pos] & 0x40)
&& writeBit(message[pos] & 0x80);
} while (good && message[pos]);
if (good) writeBit(1);
digitalWrite(_DE,LOW); // disable driver
#ifdef DEBUG
Serial.println(F("disabled driver…"));
#endif
return good;
}

3
SoftRS485.h
Unescape View File

@ -9,7 +9,8 @@ @@ -9,7 +9,8 @@
#include "Arduino.h"
extern void init485(int RO, int nRE, int DE, int DI);
extern void speed485(long pulse_length);
extern boolean available485();
extern String get485Message();
extern String get485message();
extern boolean send485(char message[]);
#endif

45
examples/SendAndReceive/SendAndReceive.ino
Unescape View File

@ -1,45 +1,18 @@ @@ -1,45 +1,18 @@
/*
This sketch demonstrates, how to use the SoftRS485 library.
This library makes use of Arduinos timer 1
*/
#include <SoftRS485.h>
int count = 0;
String message = "Message ";
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
if (send485("Test")) {
// This should send "Test" if the line is free.
Serial.println("Test sent!");
}
if (!send485("Test2")) {
// This shoult fail, as transmission of "Test" should still be on the way
Serial.println("Test2 failed!");
init485(2,3,4,5);
speed485(8000);
boolean sent = false;
while (!sent) {
sent = send485("This message is sent and received!");
}
}
void loop(){
if (available485()){ // check if we have received anything
Serial.print("messageReceived: ");
Serial.println(get485Message()); // read the received message
// send another message everytime we have received one
count++;
char msg[128];
(message+count).toCharArray(msg,128);
if (!send485(msg)){
Serial.print("Sending ");
Serial.print(msg);
Serial.println(" failed!");
}
void loop() {
// put your main code here, to run repeatedly:
if (available485()){
Serial.println("Received "+get485message());
}
}

Write Preview
Loading…
Cancel
Save