Hello all. I got an issue that has been killing me for weeks. I'm not a noob, just really terrible at this. I am trying to put together a data logger for a serial device. I have limited control over what the serial device spits out, and my code works for short serial lines that come out of the device. However, when I get a long serial line (greater than 256 characters) it doesn't work. There is nothing I can do to make the line shorter, so I just have to figure out a way to deal with it. In my full code I am tokenizing the input and only saving parts of it.
To show everyone my issue, I came up with a small simulation. I set up two Arduinos (one Arduino Pro Mini and one Teensy 35) with the TX/RX from the Pro hooked to the RX/TX of the Teensy. The Pro Mini is simulating the serial device by sending out this line every three seconds:
$MUX1230,2,1,70,2,0002,0,1,1,1,60,240,0,109,1000,100,50,100,0,656,2CC,0,652,33E,0,624,0,0,624,0,0,624,0,0,624,0,0,1,2,1,2,1,2,1,2,1,2,1,2,26,145,0,5,276,1,1,0,0,0,0,443,451,0,0,0,0,-4,-2,-624,-624,-624,-624,13,22,0,0,0,0,4,4,0,0,0,0,563,20-12-2016 04:15:01 THIS IS THE ADDITIONAL CHARS
Here is the code I have running on the Teensy, which is going to be the data logger:
#define SERIAL_BUFFER_SIZE 512
const unsigned int MAX_INPUT = 512; // how much serial data we expect before a newline
char inputLine [MAX_INPUT]; // where to store the string
byte inputPosition = 0; // input position of the inputLine character array.
bool debug = 0;
//***************************************************
void setup() {
delay(3000); // Allow for Teensy startup
Serial.begin(57600);
Serial4.begin(57600);
Serial.println("Logger is starting up");
}
//***************************************************
//***************************************************
void loop() {
while (Serial4.available () > 0) { // If the MUX sends something out, process it
processByte(Serial4.read ());
}
}
//***************************************************
//***************************************************
void processByte (const byte c) { // Used to process all bytes coming in from the MUX
switch (c) {
case 10: // If it is an end of text because we see the 'new line' character from the MUX
inputLine [inputPosition] = 0; // Terminating null byte '/0'
processInput(inputLine);
Serial.println("");
inputPosition = 0; // Reset buffer for next time
break;
default:
if (inputPosition < (MAX_INPUT - 1)) { // If we haven't reached the max input size for the array
inputLine [inputPosition++] = c; // Keep adding if not full ... allow for terminating null byte
if (debug)
Serial.write(c); // If debug true, write each character as it comes in
}
else { // In case of an overflow, clear the array and reset the pointer
memset(inputLine, 0, sizeof(MAX_INPUT - 1));
inputPosition = 0;
}
}
}
//***************************************************
//***************************************************
void processInput(const char * c) {
if (!debug)
Serial.write(inputLine);
}
//***************************************************
When I have debug 0, this is what I see on the serial of the Teensy:
Logger is starting up
THIS IS THE ADDITIONAL CHARS
It is missing the first 255 characters. It is like there is a buffer that filled up, and at the 256th character the whole buffer was cleared and now I am only seeing the rest of the characters.
When I have debug 1 (it prints each character as it comes in the serial port) then I see this:
Logger is starting up
$MUX1230,2,1,70,2,0002,0,1,1,1,60,240,0,109,1000,100,50,100,0,656,2CC,0,652,33E,0,624,0,0,624,0,0,624,0,0,624,0,0,1,2,1,2,1,2,1,2,1,2,1,2,26,145,0,5,276,1,1,0,0,0,0,443,451,0,0,0,0,-4,-2,-624,-624,-624,-624,13,22,0,0,0,0,4,4,0,0,0,0,563,20-12-2016 04:15:01 THIS IS THE ADDITIONAL CHARS
I have struggled with this for weeks now, and I have no clue what I am doing wrong. I tried the #define SERIAL_BUFFER_SIZE 512, but obviously that doesn't help.
I've tried bumping the buffer size up to 512 for both RX_BUFFER_SIZE and TX_BUFFER_SIZE and that doesn't seem to help either.
Any suggestions?
Just for completeness, here is what is running on the Arduino Pro Mini:
char str[] = "$MUX1230,2,1,70,2,0002,0,1,1,1,60,240,0,109,1000,100,50,100,0,656,2CC,0,652,33E,0,624,0,0,624,0,0,624,0,0,624,0,0,1,2,1,2,1,2,1,2,1,2,1,2,26,145,0,5,276,1,1,0,0,0,0,443,451,0,0,0,0,-4,-2,-624,-624,-624,-624,13,22,0,0,0,0,4,4,0,0,0,0,563,20-12-2016 04:15:01 THIS IS THE ADDITIONAL CHARS";
int led = 13;
void setup() {
Serial.begin(57600);
pinMode(led, OUTPUT);
}
void loop() {
digitalWrite(led, HIGH); // turn the LED on
Serial.println(str);
digitalWrite(led, LOW); // turn the LED off
delay(3000);
}
