simple PC interface to ADC/DAC

[Adam Seychell]

For a instrumentation circuit which I am designing I need to somehow
interface a 16 bit DAC and a 16 bit ADC to the PC and send data at a
continuous sample rate of 2 KHz. My idea so far is to use a USB->8bit
parallel IC (FTDI's FT245BM), and bit bang the serial data to the DAC
(TI's DAC8501) and ADC (TI's ADS320) IC's.
The software would write and read blocks of data to the 8 bit port of
the FT245BM at a fixed sample rate. The I/O lines will connect
directly to the serial I/O pins of the DAC & ADC. How will this idea
work ?
One foreseeable problem could be difficulty in writing the software to
translate the DAC and ADC samples into serial information and then
put/get into blocks of data to send/receive to the FT245BM.

FTDI have made USB interface easy since they provide free drivers and
an API for talking to the FT245BM. This takes the pain away from
software development, and appears to be almost easier than programming
the legacy PC parallel port under Windows.

Adam

 

[Nico Coesel]

For a instrumentation circuit which I am designing I need to somehow
interface a 16 bit DAC and a 16 bit ADC to the PC and send data at a
continuous sample rate of 2 KHz. My idea so far is to use a USB->8bit
parallel IC (FTDI's FT245BM), and bit bang the serial data to the DAC
(TI's DAC8501) and ADC (TI's ADS320) IC's.
The software would write and read blocks of data to the 8 bit port of
the FT245BM at a fixed sample rate. The I/O lines will connect
directly to the serial I/O pins of the DAC & ADC. How will this idea
work ?

You could modify a soundcard because it's ADC/DAC will also do fine
with DC signals. Remove the DC blocking caps and make a new
input/output circuit with a few opamps as amplifiers/buffers.

 

[MikeM]

http://www.labjack.com/entry.html