Help To Select A Microcontroller And An Adc

Dear Sir,
Here I am assigned a project where I need ur useful suggestions.

I have to do the following things prior to start my project and for that purpose suggest me.
1. Choose a microcontroller(8/16/32 bit)
2. ADC whose input range should be between 0 - 10 volts range and must have more than 3-channels for following purpose:
a) the output of pressure transducer in terms of voltage will be used by one channel whose voltage range is between 0-10 V.
b)Output of Temperature transducer will be used by other second channel whose voltage range is between 0-5 V.
c)Weight Transducer will be used by third channel whose voltage range is between 0-5 V.
3.LCD interfacing(text only) 16x2.
4.keyboard (Logitech keyboard or any alphanumeric) having alphanumeric and up-down keys.
5.data Logging facility for storing atleast 1000 data values( RAM for that purpose).
>Operater name
>Company Name
>date and time
>Reading data
6.connectivity to PC through RS-232.
7.Printer interface.

Kindly suggest me, which ADC and Microcontroller I should use.Also, for best precision it is required that I should not convert 0-10V range of ADC to 0-5 V. Suggest me an ADC having 0-10V input range and having more than 3 channels.

So please suggest me and mail me. Waiting 4 ur most valuable suggestions.

With regards
Thank You sir,

Rajesh Mahapatra

Hi,
Why can't you level shift 10 V to 5 V? There're many PICs with many analog channels with 10 bits resolution (some even 12 bits).

rajesh.mahapatra said:

Kindly suggest me, which ADC and Microcontroller I should use.Also, for best precision it is required that I should not convert 0-10V range of ADC to 0-5 V. Suggest me an ADC having 0-10V input range and having more than 3 channels.

Click to expand...

You simply need to convert it down to 0-5V, a simple resistive attenuator is all that's required - this doesn't affect your precision at all, and is how your meter and scope work.

Check huge numbers of the PIC range - something like the 16F876 will do everything you want, and it's all covered in my tutorials.

hello all

Sir,

U have suggested me to convert 0-10v range to 0-5 V. What is the external circuit required. Will u mail me the circuit diagram.

rajesh.mahapatra said:

Sir,

U have suggested me to convert 0-10v range to 0-5 V. What is the external circuit required. Will u mail me the circuit diagram.

Click to expand...

A simple potential divider, two equal value resistors, their value will depend on source and load impedances.

You probably want to buffer the resistive divider with an "op-amp buffer" (Google it. It's a very simple and popular circuit) before feeding it into the ADC because a lot of the time large resistance values are used to not distort the signal source, but these resistances are too big to charge the ADC sample capacitor fast enough as well. So you buffer it. I always do, anyways.