Serial read from sensor

[point5]

Hmmmm, I'm still trying to find out where the problem is.... I've tried cutting the code down so that it does the bare minimum to display the data required but I don't think it's right?  I have also inserted a sample counter to see when the crash happens but my noobness can't even get that right!!!  it counts 1,2,3,10,11,12,13,20 :-(

Yikes

Code: [Select]

#include <LCD4Bit_mod.h>
LCD4Bit_mod lcd = LCD4Bit_mod(2);

#include <Wire.h>

#define address 0x31

#define delayC 2000

#define baudrate 9600

char co_str[10];

char sam_str[4];

int sam;

int co;



const int data_bytes = 7;
byte data_buffer [data_bytes];

void setup()
{
 Wire.begin();
 Serial.begin(baudrate);
 lcd.init();
 lcd.clear();
 lcd.printIn("Value");
}

void loop()
{
 Wire.beginTransmission(address);
 Wire.send('R');
 Wire.endTransmission();
 
 delay(2);
 Wire.requestFrom(address, data_bytes);
 while (!Wire.available ());
 for (int i = 0; i < data_bytes; ++i)
 data_buffer [i] = Wire.receive();
 

 for (int i=0;i<7;i++)
 {
   byte c = data_buffer [i];
   if (i==1) co = c;
   if (i==2) co = (co << 8) | c;
 }
 lcd.cursorTo(2, 0);
 lcd.printIn(itoa(co,co_str,10));
 lcd.cursorTo(2, 5);
 lcd.printIn("ppm");
 sam = (sam++);
 lcd.cursorTo(2, 10);
 lcd.printIn(itoa(sam,sam_str,4));
 
 delay(delayC);

}

[PaulS]

The itoa function's final argument is the base of the conversion, not the number of digits in the value.

So, sam, at least is displaying correctly.

[point5]

Thanks Paul, it all makes perfect sense now :-) - I can see when the crash is happening now - at 96 loops this time !!

[PaulS]

I went back and read the entire thread. I don't understand all of it, but I understand enough, I think.

I'm confused about the crashing part. What's crashing? The arduino? The PC that the arduino is attached to? Something else?

[point5]

Hi Paul, its the Arduino that crashes (or at lease that's what appears to be happening - the display stops updating but the sensor LED keeps blinking as expected).  Now with the loop counter working I can see that the crash has happened after the following counts:

61,32,10,56,33,10,56,47,11,101,34

I thought a pattern was emerging but I don't think so now.

[point5]

Hmmm, I'm starting to wonder if this is a timming issue?  Is it possible to get arduino to wait until the bytes are delivered from the sensor before continuing? - the sensor transmits evey 3 seconds.

[point5]

WORKING :-)

The issue was the delay - changed from 2 to 50.

It would still be good to try and ask Arduino to wait until data is available before printing anything - just not quite sure if this is poss and how?

Thanks for all the help - it is very much appreciated.