LM35DZ and 18F2455 settings

[Mark J]

Boy do I feel a bit dumb lol!

Decided to have one more go this morning with the sensor and just displaying the result of all the samples added together with NO adjustments etc.

on the LCD it was showing something like 462 and putting the meter on the Gnd pin and the Vout pin on the sensor the meter was reading 231, so it then dawned on me that I dont need to do all the division stuff by the number of samples etc just simply divide by 2 to get the result!!!!!! DOH! and that way, I get the reading with the fractional degree's also!

Oh, and just using the VDD as the voltage reference.

One happy bunny!

[Mark J]

Well, I thought I had it working, but ive just had chance to work on the project again and found that when submersed in the aquarium (waterproofed obviously!) the thermomitor temp (tube type) shows a steady 25 C, yet the sensor on my project is all over the place (even have it in a bag in case of water seepage etc) it varies from between 22 to 28 degrees! and in a large body of water, there is no way the water temp can fluctuate so wildly (roughly 150 UK gallons)

So I am at a loss, as the code is based on other peoples posts and I thought it was working fine, but testing both sensors I still get the swings (Arghh!)

I am seriously getting annoyed with these sensors but with both swinging so much, it leads me to think its something in either my code, or getting some errenous readins through the breadboard etc.

Does anyone know if breadboards will cause these variations? as I have read somewhere that breadboards arnt exactly the greatest things etc.

Any ideas would greatly be appreciated!

[mackrackit]

Where the leads from the probe connect to the bread board. Place a 22uf , or something close, capacitor between the signal return and ground. This should settle things down. Long wires going to the probe will cause fluctuations like this.

[Mark J]

Cool thanks Dave,
It seems to have sorted the problem out.
As you can probably tell, the electronic side of things isnt my strong point lol! so many little things to think of etc.

[mackrackit]

Cool thanks Dave,
It seems to have sorted the problem out.
As you can probably tell, the electronic side of things isnt my strong point lol! so many little things to think of etc.

To be honest, I had the same problem the first time I used a LM34 at a distance. Learn as you go
The problem is not the bread board, it is long wires.

[slimpeng]

hello....if i using the 16f877A pic so the program need to change or not and the math is only use in LM35DZ or other elese...can use it.....!!

[mister_e]

The program could need some minor modifications for hardware (LCD, USART, ADCs, Comparators etc etc), but the maths have to be the same.