Particle.publish -> sprintf -> Hard fault

Troubleshooting
1

Hey there, I am trying to particle.publish a string for my first project using a DHT22

here is an excerpt of my code:

sprintf(publishString,"%.2f,%.2f,%.2f,%.2f",lightAmbient,sensorValue,lightDelta,stand,Temperatur,Luftfeuchtigkeit,Taupunkt);
//Particle.publish("VS",publishString); // I commented the publish for debug reasons

This sprintf creates a string with comma separated values of lightAmbient,sensorValue,lightDelta,stand
As soon as I add more %.2f I get a red SOS error code No1: Hard fault
I also tried %.1f %.0f and %.u

Temperatur,Luftfeuchtigkeit,Taupunkt come from a DHT22:

Luftfeuchtigkeit = dht.getHumidity();                           
Temperatur = dht.getTempCelcius(); 
Taupunkt = dht.getDewPoint();

I used Adafruit DHT library since it was the most downloaded
#include <Adafruit_DHT.h>

lightAmbient,sensorValue,lightDelta are float
Adafruit DHT seems to use float too

Any help would be very much appreciated :blush:

2

I don't think floats are implement in printf

by the way, you should use the (safer) snprintf

3

sprintf() does support floats for ages already.
Withouth any info about the definition of publishString I'd put my money on that as the reason tho' - probably too short buffer or just a char* without actually allocated memory :wink:

For seven comma seperated floats with two decimal places the buffer needs to be at least 42 bytes long
(7 x -#.##,) plus any extra places for more than one leading digits.

1 Like
4

Thanks ScruffR that seemed to do the trick

2 Likes