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Arduino crashed? after 12 hours

I am all new to the Arduino world. I wrote the following code - using the DHT22 sensor. After 12 hours, the heater for my greenhouse was not turned on when it was below the desired pace.

After turning off the power and returning back, everything returns to normal operation. I know this code is very dirty, but does it have any memory leaks? Or something else that might make it stop working?

http://pastebin.com/CcdUN3jb

Edit - I found an open counter that increased by 1 time in 2 seconds. I can not imagine that it is, but I changed it here: http://pastebin.com/nuRjHJkR

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2 answers

Council of the old army:

If you cannot fix this, draw it.

A watchdog timer is present in these microcontrollers just to keep your plants alive regardless of your code. Each pass through the loop (), you feed the dog simple

wdt_reset();

If your program freezes and stops feeding the dog, the MCU will reset.

You set the timeout for the watchdog in setup (). For your purposes, you can use a large timeout of 8 seconds, which should provide a huge margin for the execution time of the longest cycle (). How long have these sensors been reading?

See the link on the Arduino pages for a simple description: watchdog

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The only danger obvious in your code is sprintf (). The world would be a better place if no one had ever used it again. Replace it

 void loop() { ... char buf[128]; sprintf(buf, "Integer-only reading: Temperature %hi.%01hi C, Humidity %i.%01i %% RH", myDHT22.getTemperatureCInt()/10, abs(myDHT22.getTemperatureCInt()%10), myDHT22.getHumidityInt()/10, myDHT22.getHumidityInt()%10); //Serial.println(buf);

with

 void loop() { ... const size_t sizeBuf = 128; char szBuf[128+1]; snprintf(szBuf, sizeBuf, "Integer......", ... ); szBuf[sizeBuf] = '\0';

"n" versions exist for all string functions, and all of them provide a specification for the size of the destination buffer so you can be sure that they will never overflow the buffer. Note that functions do not provide null termination, so an extra line should guarantee.

So, with snprintf, you can be safe if, with an error of 1 million data errors, some unexpected string conversion occurs, your code will work.

Along this line, there is not much benefit to highlighting char buf [] inside the loop. Since the entire program executes the execution loop () endlessly, you are not saving memory resources by making this local variable on the stack. There is only a microscopic window in which the stack memory is not used. But while on the stack, if you overflow buf, overflow can erase the return address, which will undoubtedly lead to a program crash. These are all dangers without a return.

Think like that

 const size_t sizeBuf = 128; char szBuf[128+1]; void loop() { ... snprintf(szBuf, sizeBuf, "Integer......", ... ); szBuf[sizeBuf] = '\0';

In this method, memory is allocated statically, and at compile time you know how much memory your program needs.

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