01-16-2015 12:43 PM
What's the maximum switching frequency on the Digital I/O lines. Well, when used as output only obviously. I don't see this number listed anywhere on the web or on the datasheet.
Is this a number that nobody else cares about?
I don't want to use these to set static signals, I want to use them to drive serial data lines, what kind of speed can I expect?
01-16-2015 12:52 PM
Which card were you looking at?
Most DAQ boards only have static DIO, meaning they change as quickly as your software can write to it. There are some boards that can output a digital waveform, I think 4MHz is their fastest rate (haven't looked at them in a long time, so I could be way off there). And then there are R Series boards that use LabVIEW FPGA where you can toggle those lines at 40MHz based on logic that you programmed into the FPGA.
01-16-2015 01:01 PM
Errm... I'm referring to the Digital I/O in the VirtualBench product. Sorry if this is the wrong forum for that.
I'm aware NI has some boards that will handle 10, 25 and 50 MHz and up, those are clearly spec'd.
01-16-2015 01:11 PM - edited 01-16-2015 01:12 PM
The DIO lines can be used multiple ways:
Regards,
William Earle
Software Engineer
NI R&D
01-16-2015 01:12 PM
Sorry, I lost track of which forum board I was in.
I'm pretty sure the DIO are static lines. If you want a digital waveform output, you will need to use the function generator.
This was one of my gripes I had on this instrument (needs more DIO in general and some high speed Digital Output).
01-16-2015 01:15 PM
@WilliamEarle wrote:
The DIO lines can be used multiple ways:
- As general purpose I/O. This is software timed only.
- As a way to export signals, such as fgen/start. The timing is tied to the signal you are exporting.
- (added in version 1.1) To master a SPI bus. The maximum frequency supported is 31.25MHz.
- (added in version 1.1) To master an I2C bus. The maximum frequency supported is 1MHz.
So it sounds like the hardware is capabile of the hgih speed digital outputs. We just don't have the software drivers to do so?
01-16-2015 01:28 PM
@crossrulz wrote:
So it sounds like the hardware is capabile of the hgih speed digital outputs. We just don't have the software drivers to do so?
Yes, and we welcome customer feedback to help us to prioritize features.
01-16-2015 02:50 PM
I would put in a vote for this capability! I would've taken it over the SPI or I2C, if I've got a general purpose way to do it, I can (and have) written my own I2C & SPI masters.
One case where I would see this is generally useful is if I want to simulate some arbitrary data coming down the bus to my device under test. In this case, I am not expecting I2C or SPI control, just "random" data. Perhaps I don't have the actual data source hooked up or I want a reliable/repeatable pattern that can be used as stimulus on my device.
Right now I've got the purchase of a couple of VirtualBench systems hinging on this capability. If it could do this (up to 20MHz in my case), then it's an easy sell and quick sign off. If it can't, then I've got to find another justification for this thing...