conevrting the physical quantity value into digital data

[hegdeabhi]

Hi all ,

I just wanted to know the principal behind measuring a quantity and converting them to a digital set of data.
i.e suppose using some circuitry i design a meter which measures Resistance of a resistor. How do i convert them into digital data so that i can send it to a PC to handle my further application using some interface?

Thanks in advance
Abhijith

 

[btbass]

To convert a analog signal such as a voltage level to a digital value you woud use an analog to digital convertor. (A/D).
To transfer a known resistance to a pc you would just send an assci string over some comms network, such as RS232.

 

[vinodstanur]

analog to digital converter converts an analog value to a digital value. The digital value will be a multiple of a small value. In ADC the analog value is compared with discrete multiples of a small value and is tracked at a particular range and is rounded to a particular multiple of the step size(smallest discrete value).

Now the multiple obtained is coded to digital for example ,
If you give analog voltage 2.7963v then then in quantizer it is rounded to 3v and then coded to digital as 03h (hex).If more efficient quantizer then it may also include few decimals also. The 03h is a hex representation and actually its an 8 bit binary data in reality . ie '00000011'
which could be stored in a memory chip or a hard disk or any electronic data storage.
This data could be processed by a microcontroller, pc etc at any time.

 

[buiducthang]

Firstly, to read any physical value, u need convert it into digital. This is implemented through A/D converter. U can A/D converter outside your MCU or u can A/D intergrated in your MCU. (Now, there are a lot of MCU intergrated A/D converter inside it). After, u read the value, u can send it to your PC through RS232.
This is the principle for all of measurements.