Comunicating ADC+ Arduino DUE with the protocol 1-wire

30 meters is a very long distance for 1-wire communication. If you get this to work, which is unlikely, it may not be very reliable.

(I am the current maintainer of the OneWire library, by the way...)

Usually such long distances are done with 4-20 mA analog current or RS-485 serial.

Hi everyone! sorry for my later reply.

Markus thanks for your response. I decided use a simple sensor temperature. If I can't use 1wire because the manufacturer don't make 1wire ADC I won't use it. I thought to use 1wire protocol because the quantity of wire is small and with one pin of the Microcontroller I can manage all. But I won't use it because I see that there are other most common protocols.

Graynomad, the 10 sensor will stay in differents positions. The distance between Arduino-10 sensors will be approximately 30m. The distance between sensors will be short (2m).

Paul, I thought yesterday that I can use RS485 because is differential and I can connect others PIC in the bus. This is the best and easy protocol that I could use.

I think that I can do the following idea: 10 sensors temperature (with its voltage-intensity converters) and connect them with a PIC for use its internal ADC. The pic should have 10 channels ADC for connect 10 sensors. The PIC will process the analogs signals. The pic will connect with the Arduino Due with a RS485 bus.
I will need to adapt the pic's out RS232 for RS485. I think that I can use a MAX485 for adapt it. I think that I must use two MAX485 for adapt the signals between protocols. One of them in the out of the PIC and the other one in the entrance of the Arduino Due's RS232. And I read that Arduino doesn't use TTL voltages in the RS232 (0-3.3V in Arduino?)
if i use RS485 I will be able to connect more PICs in the future if I need use more Sensors (using MAX485). I don't know if MAX485 adapts the TTL signals of the PIC (because the PICs use RS232 but with TTL signals).

New diagram:
[Sensors with I-V Converters} --> PIC's ADC --> MAX485 --> (BUS RS485) <--- MAX485 <--- Arduino Due ----------> DATAS

What do you opinion? Can I use MAX485 easily for adapt the RS232-RS485 and RS485-RS232 conversion?

Thanks a lot for yor responses!! :slight_smile: :slight_smile:

Your "diagram" looks correct but your terminology is not. A PIC (or any other CPU for that matter) does not have RS-232, it has a UART that talks async serial. RS-232 is a voltage level spec (as is RS-485) that has nothing to do with the format of the data or anything like that.

I think that I must use two MAX485 for adapt the signals between protocols. One of them in the out of the PIC and the other one in the entrance of the Arduino Due's RS232.

Yes for two devices you need two RS-485 transceivers, one at each end. Every extra device added needs another transceiver.

The MAX485 is a common choice and of course it works OK, but I don't think it's available in a 3v3 version which you need for the Due end. Check that out, if not try a LTC1480 or similar that does run at 3v3.

This is the best and easy protocol that I could use.

RS-485 is not a protocol, a protocol is code that implements a set of rules that determine the format of the data being transferred and optionally how to handle errors etc. You will have to write the protocol. That said yes I think RS-485 is the best method.

I can connect others PIC in the bus

Again, why a PIC? Not that there's anything wrong with PICs but you won't get much (or any) help here with them.


Rob

Thanks Graynomad! I am learning more in this forum :slight_smile:

The part of the pics is solved (that part is not a big problem now). I will send from Pics to Arduino a value type Float. For example, the smaller value that I can obtain with the measure of the Pic's ADC(10bits) is 5V/1024 =0,00488V. The smaller value that Arduino will receive by serial port is that. Will the arduino's serial port receive packet of the 8bits? I will send to Arduino the value in string form by pic's serial port. If later I need send by arduino's serial port (to other platform, for example my laptop) that smaller value I can use a simple "print()" ?

I wish that you understand that explanation. Thanks for your responses.

Will the arduino's serial port receive packet of the 8bits?

It will receive whatever you send to it.

I will send to Arduino the value in string form by pic's serial port.

Then that's what it will receive (subject to faults in the line etc).

If later I need send by arduino's serial port (to other platform, for example my laptop) that smaller value I can use a simple "print()" ?

Yes, you can just echo the same data or change it as you see fit.

I won't ask again why you are using a PIC, I'll just assume there is a good reason.


Rob

Thanks a lot Grainomad and the other users with your help. I am continuing with this project and developing it. :slight_smile: :slight_smile:

I am using pics because the idea is comunicate the Arduino and the sensors with a only bus. I will use the pics' ADC to make the conversion (Analog to digital) and I will save problems (probably this isn't the best metod).

I am using pics because the idea is comunicate the Arduino and the sensors with a only bus.

That's a reason to use a processor of any kind and a reasonable decision. I'm just curious as to the choice of a PIC because you won't get much (any) help here with it. So if you are already proficient with PICs fair enough, but if you have to learn a processor anyway it might as well be an AVR.


Rob

Yes, I will use AVR. I think that is a good idea to start with microcontrollers. Now, I am programing the Arduino Due. I am trying to do a program with this algorithm:

The Arduino will receive instructions from my laptop by serial port. The laptop will send two thinks. For example, if I want that the sensors send me its information (temperature information) I will send to Arduino the following string: "$ADQ,Pxx,CHx" where the variable [ x ] is a number 0 to 9. Example: If I want receive sensor's information (microcontroller 1 's channel0) I will sent to Arduino: "$ADQ,P01,CH0" and Arduino send this information to microcontrollers connected by bus RS485 and Arduino will wait for resply from microcontrollers. The other think that laptop can send to arduino is the option of automatic mode.

The laptop too will send to Arduino if I want automatic mode. If I want automatic mode Arduino will send information request by serial port to microcontrollers. Example: if want that Arduino send automatically the strings "$ADQ,Pxx,CHx" by Serial port I need send to Arduino --> Automatic mode = 1. If Automatic mode is 0 Arduino will receive the string from laptop and will retransmit this information to microcontrollers.

Arduino will receive sensors' information from microcontrollers by serial port and only will retransmit the received strings to laptop by serial port. Example: If Arduino send by bus the following string: "$ADQ,P01,CH0" the microcontroller 1 will respond with the following string :"$ADQ,P01,CH0,n" where [ n ] is the result of the ADC's conversion in the microcontroller (ADC 10 bits).

I need use two serial ports from Arduino: the first SERIAL0 to connect laptop with arduino and the second SERIAL1 to connect the bus (with microcontrollers) and Arduino. Fisrt, I will send always the string of automatic mode (AutomaticMode = 0/1) and later if I want manual mode (AutomaticMode=0) I will send the string that I want send (for example "$ADQ,P01,CH0").

I have done some think but I don't know if I am going by good way.

void setup() {
** int AutomaticMode=0;**
** int CALL=0;**

** boolean FlagUART= false;**

** char DataReceivedMODE[2]={0};**
** char DataReceivedSERIAL0[13]={0};**
** char DataReceivedSERIAL1[19]={0};**

** Serial.begin(9600);**
** Serial1.begin(9600);**

}
void loop() {

** CALL= UART0();**
** CALL= AnalyzeSensors();**
** CALL= UART1();**
}
void UART0(){
while(Serial.available()){
if(FlagUART==false){

** FlagUART=true;**

** DataReceivedMODE= Serial.read();**

** Switch (DataReceivedMODE){**

** case '1':**

** AutimaticMode= 0;**

** break;**

** case default:**

** AutomaticMode= 1;**

** break;**

** }**
** }**
else if {FlagUART=true||AutimaticMode==1){

** FlagUART=false;**

** DataReceivedSERIAL0=Serial.read();**
** }**
else{
** FlagUART=false;**
}
** }**

}

** return(0);**

}

void AnalyzeSensors(){

** if (AutomaticMode==1){**

** Serial1.print("$ADQ,P00,CH0");**
** delay(1);**
** Serial1.print("$ADQ,P01,CH0");**
** delay(1);**
** Serial1.print("$ADQ,P02,CH0");**
** delay(1);**
** Serial1.print("$ADQ,P03,CH0");**
** delay(1);**
** Serial1.print("$ADQ,P04,CH0");**
** delay(1);**
** Serial1.print("$ADQ,P05,CH0");**
** delay(1);**
** Serial1.print("$ADQ,P06,CH0");**
** delay(1);**
** Serial1.print("$ADQ,P07,CH0");**
** delay(1);**
** Serial1.print("$ADQ,P08,CH0");**
** delay(1);**
** Serial1.print("$ADQ,P09,CH0");**
** delay(1);**
** Serial1.print("$ADQ,P10,CH0");**
** delay(1);**

** }**

** else{**

** Serial1.print(DataReceivedSERIAL0);**
** delay(1);**

** }**
return(0);
}
void UART1() {
while(Serial1.available()){
DataReceivedSERIAL1=Serial1.read();

}
** return(0);**

}

Please use CODE tags and provide code that at least compiles, have you tried that code or is it just a collection of semi-random instructions?

For example all the variable declarations in setup() are local to setup(), they are not global, so all references to them from the rest of the code causes errors.

 CALL= UART0();
  CALL= AnalyzeSensors();
  CALL= UART1();

These functions are void functions, they do not return a value. And even if they did you do not use CALL anyway. Then there's

     AutimaticMode= 0;
            break;
            case default:
            AutomaticMode= 1;

AutimaticMode or AutomaticMode?

You should at least try to provide working code, or at least code that compiles.


Rob

Sorry. I am working it and I'm thinking, I have a doubt now... If I want use a Switch with the data received by serial port I can use this data directly? For example, Arduino will receive by serial port "1" or "0" and will select one case. The following code is correct?

DataReceivedMODE= Serial.read();

Switch (DataReceivedMODE){

case '1':
AutomaticMode= 0;
break;

case default:
AutomaticMode= 1;
break;
}

If you only have those two possibilities like that then an if() is more appropriate

if (DataReceivedMODE == '1')
   AutomaticMode= 0;
else
   AutomaticMode= 1;

or even better (but more cryptic)

AutomaticMode = DataReceivedMODE == '1' ? 0 : 1

Rob

Thanks!! I am learning a lot. Other problem solved :). But now I am trying receive correctly the datas from serial port. For example, If I need receive from serial port 0 the string "$ADQ,P00,CH0" I was reading that the function Serial.read() only returns the first byte available in the buffer. My string have 12 bytes (without count the null character). If I work with the variable [char DataReceivedUART0[13];] and I do DataReceivedUART0=Serial.read(); I only will receive the first byte available in serial port? or willl I need use a bucle for if I need save 12bytes ("$ADQ,P00,CH0")? -->

for(i=0; i<13; i++){
DataReceivedUART0*=Serial.read();*
}[/b]
When one byte is read with serial.read() in serial port this byte, later, is removed?
Thanks a lot!!!

for(i=0; i<13; i++){
DataReceivedUART0=Serial.read();
 }

Notice anything missing? I bet that's not your actual code. That's why we insist on people using CODE TAGS. (the # button in the tool bar when editing your post)

I suspect your problem is simple but we need to see the code properly presented without missing parts.


Rob

This is the code. Sorry. :slight_smile: This code have errors that I don't know what is. (Errors like dd:36: error: ISO C++ forbids comparison between pointer and integer).

char DataReceivedMODE[2]={0};
 char DataReceivedSERIAL0[13]={0};
 char DataReceivedSERIAL1[18]={0};
 int AutomaticMode=0;
 int i=0;
 boolean FlagUART= false;


void setup() {
  
  Serial.begin(9600);
  Serial1.begin(9600);
  
}


void loop() {
  
  UART0();
  AnalyzeSensors();
  UART1();
  
 }
 
 
void UART0(){  //This function receve the datas from my laptop (Mode and Resquest sensor's infromation)

while(Serial.available()){

if(FlagUART==false){
  
  FlagUART=true;
  
  
     if(DataReceivedMODE == '1'){
       
       AutomaticMode= 1;
       
       }
       
      else{
        
        AutomaticMode= 0;
      
       }
  
  }

else if (FlagUART=true||AutomaticMode==1){
  
  FlagUART=false;
  
  for (i=0;i<13;i++){
  
  DataReceivedSERIAL0[i]=Serial.read();
   }
 }

else{

  FlagUART=false;

}

  }
 
   

 }
 

 
 void AnalyzeSensors(){
   
   if (AutomaticMode==1){
      
     Serial1.print("$ADQ,P00,CH0");
     delay(1);
     Serial1.print("$ADQ,P01,CH0");
     delay(1);
     Serial1.print("$ADQ,P02,CH0");
     delay(1);
     Serial1.print("$ADQ,P03,CH0");
     delay(1);
     Serial1.print("$ADQ,P04,CH0");
     delay(1);
     Serial1.print("$ADQ,P05,CH0");
     delay(1);
     Serial1.print("$ADQ,P06,CH0");
     delay(1);
     Serial1.print("$ADQ,P07,CH0");
     delay(1);
     Serial1.print("$ADQ,P08,CH0");
     delay(1);
     Serial1.print("$ADQ,P09,CH0");
     delay(1);
     Serial1.print("$ADQ,P10,CH0");
     delay(1);
    
   }
     
    else{
    
    
    Serial1.print(DataReceivedSERIAL0);
    delay(1);
     
     }



}


void UART1() { //This function receive the datas from microcontrollers

while(Serial1.available()){

for(i=0;i<18;i++){  
  
 DataReceivedSERIAL1=Serial1.read();
 
 }

 Serial.print(DataReceivedSERIAL1);
  
}
 
  
}
if(DataReceivedMODE == '1')

You are comparing an array with a char

if(DataReceivedMODE[0] == '1')

Will compile, as to the logic of the program I'll look at that.


Rob

OK yes. Now it will compile! Thankss. But I have a question is possible simplify when I send by serial port the strings "$ADQ,P00,CH0", "$ADQ,P01,CH0" etc? And I don't know if I do correctly the assignation of the received datas from serial port.

 char DataReceivedMODE[2]={0};
 char DataReceivedSERIAL0[13]={0};
 char DataReceivedSERIAL1[18]={0};
 int AutomaticMode=0;
 int i=0;
 boolean FlagUART= false;


void setup() {
  
  Serial.begin(9600);
  Serial1.begin(9600);
  
}


void loop() {
  
  UART0();
  AnalyzeSensors();
  UART1();
  
 }
 
 
void UART0(){  //This function receve the datas from my laptop (Mode and Resquest sensor's infromation)

while(Serial.available()){

if(FlagUART==false){
  
  FlagUART=true;
  
  
     if(DataReceivedMODE[0] == '1'){
       
       AutomaticMode= 1;
       
       }
       
      else{
        
        AutomaticMode= 0;
      
       }
  
  }

else if (FlagUART=true||AutomaticMode==1){
  
  FlagUART=false;
  
  for (i=0;i<13;i++){
  
  DataReceivedSERIAL0[i]=Serial.read();
   }
 }

else{

  FlagUART=false;

}

  }
 
   

 }
 

 
 void AnalyzeSensors(){
   
   if (AutomaticMode==1){
      
     Serial1.print("$ADQ,P00,CH0");
     delay(1);
     Serial1.print("$ADQ,P01,CH0");
     delay(1);
     Serial1.print("$ADQ,P02,CH0");
     delay(1);
     Serial1.print("$ADQ,P03,CH0");
     delay(1);
     Serial1.print("$ADQ,P04,CH0");
     delay(1);
     Serial1.print("$ADQ,P05,CH0");
     delay(1);
     Serial1.print("$ADQ,P06,CH0");
     delay(1);
     Serial1.print("$ADQ,P07,CH0");
     delay(1);
     Serial1.print("$ADQ,P08,CH0");
     delay(1);
     Serial1.print("$ADQ,P09,CH0");
     delay(1);
     Serial1.print("$ADQ,P10,CH0");
     delay(1);
    
   }
     
    else{
    
    
    Serial1.print(DataReceivedSERIAL0);
    delay(1);
     
     }



}


void UART1() { //This function receive the datas from microcontrollers

while(Serial1.available()){

for(i=0;i<18;i++){  
  
 DataReceivedSERIAL1[i]=Serial1.read();
 
 }

 Serial.print(DataReceivedSERIAL1);
  
}
  
  
}

Another problem

	while(Serial1.available()) {
		for(i=0;i<18;i++){  
			DataReceivedSERIAL1[i]=Serial1.read();
		}

Let's assume there was a single byte available so this code it executed. What makes you think there are 18 bytes? and anyway aren't there just 12 bytes in the received string?

	if (Serial1.available() >= 12) {
		for(int i=0; i<12; i++){  
			DataReceivedSERIAL1[i]=Serial1.read();
		}

Same in UART0().

Sorry, I still haven't thought about the logic of the program as I keep finding errors like these.


Rob

Ok now let's look at the program, as I understand it you can get the same strings from either the PC or another Arduino...or maybe not.

The two arrays are different sizes, are the strings expected from the PC and other Arduino also different sizes?

Can you spell out the program requirements in a few lines like,

if I get a string from Serial0, parse it and do X
if I get a string from Serial1, parse it and do Y

EDIT: I see you did describe things fairly well in post #20, I'm trying to get my head around it.


Rob

If I received by serial port 0 from laptop the string "$ADQ,P00,CH1" in the buffer I must have 13 bytes (12 bytes + NULL character) no?

The laptop send me by the same serial port differents strings. For example string of Mode ("0" or "1") and the strings like "$ADQ,P00,CH1". How I can differentitate between these strings in the same buffer? :~

Example: If I want receive sensor's information (microcontroller 1 's channel0) I will sent to Arduino: "$ADQ,P01,CH0" and Arduino send this information to microcontrollers connected by bus RS485 and Arduino will wait for resply from microcontrollers.

So in this case the data received from the PC is simply echoed to the sensors. Is that the case?


Rob