using several ADC's (ad7476a) via SPI

[freitas]

Hi:

I have BF537-EZkit and AD7476A-DBRD and I put it to work using the "SPI and UART" project..

But in my project I will need several AD7576A.. how do I configure the SPI to do that?

I used the "analog read I/O" inside the while loop (that writes via UART) but it reads the ADC too slowly for AC reading..

What's the correct way to do it? The UART is no need, I only use it to see the values read by the ADC..

Thanks in advance,

António Veríssimo de Freitas

[thomas.baudouin]

Hi,

If I understand correctly, you want to digitize various analog signals and to read this data with the Blackfin. One option to do that would be to use only one ADC and to have a multiplexer in front of the ADC. The multiplexer will allow you to switch between the various analog signals. The multiplexer would be controlled by the Blackfin.

Best regards, and good luck!

[freitas]

Hi:

That was the solution I was going to do, until my "supervisor" advised me not to use a MUX and use several ADC's instead (because I need a fast reading to measure harmonic distortion)

By the way, if I go with the multiplexer option, I need 3 "flagpins" to choose the input (8 inputs) what pins from the processor do you recomend to use? and how do I choose them in the labview?

Thanks in advance,

António Veríssimo de Freitas

[thomas.baudouin · Accepted solution]

Hi,

In order to control the operation of the multiplexer, you can use a digital output of the Blackfin. You can use the PPI on the Blackfin to do that. You will be able to control it in LabVIEW with the Blackfin functions that were added to the LabVIEW palette.
If you are not familiar with LabVIEW, you can learn here:
http://digital.ni.com/public.nsf/allkb/7D5F60ADBFD9CDC2862572BA005DD96A?OpenDocument
And then,the exercises provided with the EZkit should help you ( http://zone.ni.com/devzone/cda/tut/p/id/6949 ).

Best regards