Translating Analog Signal into Digital and Displaying it With Led's

[marcusaurelius]

Hello everyone. I am working on a homework project, and at this final stage, this is my situation :

I have a circuit where an LM35 chip yields temperature in a voltage rate proportional to the ambient centigrade value (eg. 20 degrees would be 20mV V). Then, after i found out i had to turn this into a digital signal to be able to display this voltage on a seven segment display, i decided to use ADC0831 and to use it's binary output, i decided to use MAX7219 (includes a decoder for binary signals and a driver to drive the 7 segment displayers).
Here's my first sticking point, and despite some research, which i couldn't quite understand.

ADC0831 has 8 terminals, namely CS, Vin+, Vin- , GND on one side and Vcc, Vref, CLK and DO on other.
What exactly do these terminals do? CS,CLK and DO are of particular interest to me. And I'd also appreciate advice on how best i'd use these terminals. My goal is to display temperature on the 7 segment displays with 2 digits , from 0 to 50 celsius.

So far i saw that CS activates the chip , CLK puts in the working frequency of the chip and DO is the binary signal that is translated from the analog value. But how exactly? What should be my CLK or CS value? What is the correspondence between the ambient temperature and the 8 bit signal?

 

[Harald Kapp]

ADC0831 has 8 terminals, namely CS, Vin+, Vin- , GND on one side and Vcc, Vref, CLK and DO on other.
What exactly do these terminals do? CS,CLK and DO are of particular interest to me.

Have you had a look at the datasheet? This is an ADC with serial output, but it is not suitable to interface directly with the MAX7219 controller.

What is the correspondence between the ambient temperature and the 8 bit signal?

That's up to your circuit:
The LM35 yields a voltage proportional to temperature.
The ADC0831 yield a digital value proportional to voltage. This is a binary number that needs to be scaled to give a value proportional to temperature.
You will need a microcontroller to read data from the ADC, scale the value correctly and send it to the 7-segment driver. By chosing a microcontroller with enough I/O-pins and using a multiplexing scheme you will not need the extra 7-segment driver. This part can be done in software by the microcontroller.

You'll have to set up the signal chain such that temp -> voltage -> digital value -> display scales correctly.

Put these serch terms into your favorite search engine: 'lm35 digital thermometer' and you'll find many complete projects you can base your own work on.