7953 FPGA with 6581 Adapter Global Clock Inputs

[JHaas]

I'm very new to FPGA design with LabVIEW. I have a 7953 FPGA card that connects to the 6581 adapter. Looking at this brochure, for the 6581,

( http://www.ni.com/pdf/products/us/cat_ni6581.pdf )

on page 3, it states "Note: Clock is connected to NI FlexRIO FPGA module global clock inputs". I think this means that on DDCA pin 67 of the 6581, I can feed an external clock in that is accessible in my LabVIEW FPGA code at the 7953's global clock inputs? I'm not sure what those global clock inputs would be on the 7953. Would it be one of the choices presented to me as shown in the attached picture?

Sorry if this question is off base......

[MorganS]

Hi JHaas,

The FlexRIO adapter modules can provide a clock to the FPGA so that you can synchronize your FPGA's operation with the adapter module. The way you set this up is by specifying the FPGA Base Clock. Instead of using the standard 40 MHz clock, you will use the clock from the 6581. This setting is in the FPGA properties in the project:

From there, you can select the I/O module clock and configure it according to the specs you need:

Hope this helps!

Morgan S

Applications Engineer

National Instruments

[MorganS · Accepted solution]

Hi JHaas,

I think I may not have fully answered your question.  Yes, you can bring an external clock into the 6581 that is accessible in your FPGA code.  Take a look at this KnowledgeBase article which has some more detail about which pins to use, and how to use the clock in a single-cycle timed loop.

[angelo_podda]

Hi,

I have an other question. the module 6581 has two global clock inputs. I mind if is possible to use simultaneously  "Global clock 0" to acquire signals from DDCA, and "Global clock 1" to acquire signals from DDCB.  Clocks connected to "Global clock 0" and "Global clock 1" are completely independent from each other (for example "Global clock 0" at 15.26MHz and "Global clock 1" at 20MHz). In other words all digiltal inputs share the same clock, or is possible to use two different clock for signal on the two connectors?

Thank-you

[SunainaK]

Hi angelo_podda,

As long as the DIO is in the SCTL from the clock source you want it to be in, it will work. So you could have 2 SCTL's where 1 has DDCA DIO in it with the clock source IO Module Clock 0 and a separate SCTL with DDCB DIO in it with the clock source being IO Module Clock 1 and vice-versa.