Reading 12 bits on a Silab board

[Tiffany_M]

I have a Silab board that has 12 bit AD and the serial command only allows for 8 bits.  Is there any way I can access all 12?

Message Edited by Tiffany_M on 04-28-2006 10:05 AM

[Dennis_Knutson]

I think it's important to make the distinction between the RS-232 serial protocol and a serial bit stream. RS-232 has a max of 8 data bits and unless the A/D board is splitting the data into two frames, you can't use the regular serial port. The board you have probably doesn't even support the signal levels of RS-232 (+/-12 volts). You might want to think about using something like the NI-6533 or NI-6534 which are hardware timed digital I/O boards.

[kfc]

Well, If you are using a Silabs eval board for one of their 12bit a/d micros (C8051F020), then the eval board is equiped to "speak" to the com port of the computer.  What you need to do stream the 12 bit conversion out in the form a 2 bytes, look at this link's example code that uses the internal temperature sensor and the printf statement to send data to the uart port.

http://www.silabs.com/public/documents/tpub_doc/anote/Microcontrollers/Precision_Mixed-Signal/en/an1...

You could just modify this to send out a 16bit value with the upper nibble padded with zeros.

Cheers

[Tiffany_M]

Thanks for the lead.