HSDIO with multiple voltage level

[moonss2]

Hi,

I am using PXI-6552 HSDIO. I am usign 15 channels to drive 15 signals into a CPU using  single test pattern (hws), but they are different family logic for this 15 signals which need to drive at different voltage level. (like 3.3V, 1.8V, 1.05V).

I try to do this , but  it prompt error. I attached the VI which i have written.

Can somebody advise on this? thank you.

[tbob]

I don't think you can set different voltage levels for different channels at one time.  Maybe I'm wrong.  I've used the PXI-6551 many times and it doesn't allow different voltages on a per channel basis.  Maybe the 6552 does, but after reading the documentation on it, I don't think it supports this.  If you have to use all 15 channels at one time, you may be stuck.  The only other solution is to use 3 different 6552 cards, one for each voltage level.

What is the error you are getting?

[Aaron_W.]

moonss2,

Thanks for posting on the NI Forums. What tbob said is correct, you cannot have different voltage levels on different generation channels. With the 655X device you are allowed to have one voltage level for the generation session, such as channels and triggers. You can also have a different voltage level for the acquisition session. The suggestion to use multiple 6551 cards would work, and you could use our T-CLK driver to make sure the cards were synchronized with one another. 

Message Edited by Aaron W. on 04-20-2010 01:43 PM

[JuanCarlos]

Since there is only 1 generation voltage level for all lines, there are a couple of tricks you can try. If the patterns that you need to generate at different voltage levels are not synchronized, you can configure the voltage generate the 3.3V patterns, then reconfigure you channels and voltage to 1.8V and generate the second pattern; this will increase your test times, but may be able to get you up and running. Another option may be to add termination resistors to the lower voltage channels, the 655x has an output impedance of 50 Ohms, if you add a 50 Ohm termination resistor to a line you will get half the voltage on that line; i.e.. You configure all channels for 3.3 V and add 50 Ohm termination resistors to the 1.8 V channels; due to the voltage divisor, you'll get 1.65 V on the terminated lines, that is probably enough to drive the 1.8 V lines without overdriving them. Ultimately, you can get a level-shifter IC to translate from 3.3V to the other levels, but as you can imagine this can get complicated.

I hope this helps, let me know if you have any further questions. 

Juan Carlos

NI

[tbob]

I'm going to piss NI off here and suggest a competitor's product.  Hopefully, NI will develop a similar HSDIO.  Geotest makes a HSDIO that has individual voltage controls for each channel.  I forgot the model number of the card, and I'm not quite sure if it is fully released and on the market yet.  Go to geotestinc.com.  It might be the GX5290.  They make Labview drivers for their product, but their drivers are a bit more complicated to use than NI's drivers.  Just a bit.  Geotest has good customer service and technical support.  They also produce a TestStand like sequencer called ATEasy.  You might want to check it out also. 

I'm doing this to keep competition alive to make NI keep in line with their pricing.

If you call Geotest, talk to Bob Spzilla or Dale Johnson and tell him Bob Duet sent you.

[tbob]

I have just thought of another solution, but this one involves extra hardware.  Are you familiar with level shifters?  ICs that take in a certain voltage level and shifts them to a different level.  You could wire your highest voltage lines (for example 3.3 v) directly to your device under test (DUT).  For the other lower voltage levels (2.2, 1.8,etc), wire the HSDIO outputs to the inputs of level shifters, wire the appropriate output voltage (2.2 for example) to the level shifter (maybe from a power supply or an analog AO), then wire the level shifter output to your DUT pins.  You can do this for a number of voltage groupings.  Just build an interface board for the level shifter circuit.  Look up level shifters on google, or on Digi-Key, Mouser, or Newark.

Some level shifters are bi-directional, meaning they will step down the voltages in one direction, then step them up in the other.  This will allow you to interface the PXI-6552 card to multiple pins on your DUT, and just specify one voltage level on the HSDIO.