DigiDisco: trigger level adjustable ?

[HoWei]

I am triggering in sync mode, but the trigger signal is not super-clean. Sometimes it seems to trigger wrongly and I would like to change the trigger level for the DIN0..23.

Is this possible in the DigitalDiscovery ?

I only found the "AnalogInTrigger" functions, and when reading out they are all 0.

 

[edit:]

I found the follwing command:

pfsLevelLow = c_int()
pfsLevelHigh = c_int()
pfsEdgeRise = c_int()
pfsEdgeFall = c_int()

dwf.FDwfDigitalInTriggerInfo(hdwf, byref(pfsLevelLow),byref(pfsLevelHigh),byref(pfsEdgeRise),byref(pfsEdgeFall));

print(pfsLevelLow, pfsLevelHigh, pfsEdgeRise, pfsEdgeFall)

but this returns:

c_long(16777215) c_long(16777215) c_long(16777215) c_long(16777215)

 

 

[attila]

Hi @HoWei

To heave clear signal make sure to:
- have proper grounding between devices and circuits,
- use twisted (with ground like it is on HS adapter) or shielded wires to reduce crosstalk,
- termination to reduce ringing...
https://store.digilentinc.com/digital-discovery-high-speed-adapter-and-logic-probes/

The input logic threshold is about half of the set digital voltage.
You can also try applying pull-up/down.

See the Digital Discovery section of the WF SDK manual.

Here you have some related posts:

 

[HoWei]

My DUT has a 1.8V SPi intput - thus I am setting the DIO supply to 1.8V before I programm it.

Afterwards I want to capture the output of the DUT with DIN0..23 which are 3.3V CMOS signals.

Whithout readjusting the DIO supply, the DIN threshold would be ~0.9V, right ?

 

To have the correct DIN threshold at ~1.6V, I would need to make all DIOs TS(High-Z) and readjust the DIO supply to 3.3V ?

 

 

[attila]

Hi @HoWei

Yes. DIOs to 0 or Z, then change the VIO to 3.3