CODEWITHSUNDEEP
arduinoprintf
Luis Del Barrio
Luis Del Barrio

Reputation: 57

Sprintf is not printing everything in the line (Arduino)

I created a small model plane with arduino, and now want to create a simple FCS page on the serial monitor. I used printf to print all the variables in one line, but it isn't printing everything in the printf line.

char buf[150];
 sprintf(buf, "\t LEFT \t RIGHT \n AIL \t %d \t %d \n STAB \t %d \t %d \n TEF \t %d \t %t \n LEF \t %d \t %d \n RUD \t %d \n\n SPD  %f KTS  %f M \n AOA  %f", leftAilPos, rightAilPos, leftStabPos, rightStabPos, TEFPos, TEFPos, LEFPos, LEFPos, RuddPos, Spd, AoA);
 Serial.println(buf);

I thought this would print something like this:

          Left   Right
AIL        20      -15
STAB       12      12
TEF        5       5
LEF        3       3
RUD        0

SPD       250KTS  0.37M
AOA         3.5

However, on the serial monitor, only the first few lines get printed:

          Left   Right
AIL        20      -15
STAB       12      12
TEF        5

Is there something I'm doing wrong or missing?

Upvotes: 2

Views: 733

Answers (3)

Luis Del Barrio
Luis Del Barrio

Reputation: 57

So I realized where my error was, I typed %t instead of %d in one of the variables, here;

TEF \t %d \t %t \n

This wasn't popping up as an error but it kinda stopped showing the rest of the line. Fixing this now actually shows everything.

Thanks to everyone else for trying to help, and I'll actually still use some of those solutions hoping to make my program a bit more efficient.

Upvotes: 0

Delta_G
Delta_G

Reputation: 3243

Since you are just printing out to Serial, the best thing for you to do is to remove the sprintf altogether and simply use a bunch of Serial.print and Serial.println statements. The code will take more lines on the page, but will actually be a lot smaller since you don't have to bring sprintf in, it's a huge function. It's more efficient that way too, sprintf is an expensive function. Anything on the other end of the line will have no way of knowing if you printed it all with one line or with a million Serial.print one for each letter. Serial output is buffered so there's no difference as far as the receiver is concerned.

Upvotes: 1

Sourabh Choure
Sourabh Choure

Reputation: 733

Your code is absolutely fine. What you are not considering is the serial port buffer size which is just 64 Bytes. Anything larger than that will truncate. So, you need to split your data into two parts to successfully send it over the serial port.

Or else you can modify the size of the serial buffer by altering the Arduino core library files.

Update: In newer version of Arduino IDE, they have changed the location of the SERIAL_BUFFER_SIZE

Here is the code snippet from my [Local Drive](C:)\[Installation Path](Program Files (x86))\Arduino\hardware\arduino\avr\cores\arduino

In File USBAPI.h

#ifndef SERIAL_BUFFER_SIZE
#if ((RAMEND - RAMSTART) < 1023)
#define SERIAL_BUFFER_SIZE 16
#else
#define SERIAL_BUFFER_SIZE 64
#endif
#endif
#if (SERIAL_BUFFER_SIZE>256)
#error Please lower the CDC Buffer size
#endif

change to

#ifndef SERIAL_BUFFER_SIZE
#if ((RAMEND - RAMSTART) < 1023)
#define SERIAL_BUFFER_SIZE 16
#else
#define SERIAL_BUFFER_SIZE 256
#endif
#endif
#if (SERIAL_BUFFER_SIZE>256)
#error Please lower the CDC Buffer size
#endif

Note: Don't increase beyond 256 Bytes as there are some issues and the serial port tends to behave erratically.

Upvotes: 3

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