Digital thermometer ...................... help !!!

[#MAAM#]

Hi guys

i`m design a digital thermometer (adc0804 + LM35 + at89c52) i confused about how to determine vref/2 pin9 in adc0804 ........ when i put it at 1.28v it give me the correct temperature when i vary the value of voltage it give me wrong temperature value ............ i want to know how i calculate the correct value of vref/2 ??



i upload my proteus file and keil file. thanks in advance.

 

[mvs sarma]

you may read this linked pdf. as per them vref is nothing but supply given to V+ of the chip. always keep input at Vdd/2. Suppose Vref is 5V, the input could be 2.5V max.

**broken link removed**

 

[#MAAM#]

you may read this linked pdf. as per them vref is nothing but supply given to V+ of the chip. always keep input at Vdd/2. Suppose Vref is 5V, the input could be 2.5V max.

**broken link removed**

when i put it 2.5v ,,,,,,,, it give me wrong temperature !!!

 

[bajgik]

check this link might help with the information:
Tutorial on 8051 adc with lm35 **broken link removed**
Digital thermometer project: **broken link removed**

 

[#MAAM#]

check this link might help with the information:
Tutorial on 8051 adc with lm35 **broken link removed**
Digital thermometer project: **broken link removed**

this tutorial contain the same information that i know ..... we put vref/2 with 2.5v but this confused with simulation in proteus !!! when i put 1.28v it works well !!!

 

[#MAAM#]

can any one help me !!

 

[ckshivaram]

hi, check this
**broken link removed**

 

[Medtronic]

Dear All My Friends

This is full 8051 and adc project

Thanks

Best Regards

MedTronic

 

[BurnOut_tesla]

#MAMA#,
You can do it with DS1820, it is didgital temperature sensor which communicate on one wire protocol.
With the smallest microcontroller you can interface it.
You dont need to have reference voltage also.