Do sensors "wear out" when they are being used?

I have a project where I'm using and RTC (DS3231) and temperature sensors (DS18b20).

The MTTF for both is more then 5000 years according to http://www.maximintegrated.com/reliability/product/DS1820.pdf http://www.maximintegrated.com/reliability/product/DS3231.pdf but the MTTF cannot be used as life-time off a product...

I was wondering if I can poll the hell out of them? Or will they fail quicker when they are used more often?

The DS18B20 is slow, so you have to use delays as you can read in the datasheet.

If you keep that in mind, you can poll the DS18B20 and RTC as much as you like, they will never ever fail faster because of that.

Polling the DS18B20 continuesly, is a normal sitution. I have a Arduino as I2C Slave with a DS18B20. The DS18B20 is polled continuesly in the background. When a request is received via I2C for the temperature, the latest temperature is replied.

Thank you erdin.

Conserning the DS18b20 and it's slow speed. Am I correct when i assume that the 9-bit word gives me a resolution of 0.34°C? 2^9 / temprange (-55 ~ +100°C) 2^9 / 155 = 0.34°C

Edit: This is explained in the datasheet:

OPERATION—MEASURING TEMPERATURE The core functionality of the DS18B20 is its direct-to-digital temperature sensor. The resolution of the temperature sensor is user-configurable to 9, 10, 11, or 12 bits, corresponding to increments of 0.5°C, 0.25°C, 0.125°C, and 0.0625°C, respectively.

Another question arises: Why would someone want to use a resolution up to 0.0625°C if the sensor itself is only accurate up to +/- 0.5°C?

Polling the ds3231 too frequently will alter the clock rate. If you need to perform an operation every second or every minute, use an alarm interrupt.

Why would someone want to use a resolution up to 0.0625°C if the sensor itself is only accurate up to +/- 0.5°C?

It can still be useful for measuring changes in temperature even if the absolute value is not accurate.

Pete

el_supremo: Polling the ds3231 too frequently will alter the clock rate.

Could you explain that ? Is that even possible ?

I use 12 bit for the DS18B20. I think most people do. It is nice to see a very small change. The absolute accuracy is often better than 0.5 degrees Celsius.

I had a problem with the ds3231 running very slow (or fast, can't remember) last year when I was reading the interrupt bit in the control register every time the loop function was called. I changed the code to use interrupts and had no trouble with it since. I presumed that it was the polling that caused the problem.

Pete