Triggering on threshold

[Loic VINET]

Hello

I am using a digital discovery device.

in a python program, I would like to trigger on a threshold value. Assuming I am using the 12 first bits, dio 0 to 11, I would like to trigger as soon as I have a value greater than a value between 0 to 4095 = (1<<12)-1.

I tried dwf.FDwfDigitalInTriggerSet(hdwf, c_int(threshold), c_int(4095), c_int(4095), c_int(0)), but it is not working.

First, is it possible to trigger on threshold?

Second, how should I do it?

Thank you

[attila]

Hi @Loic VINET

A 12bit bus value range is 0 to 4095. It can't be greater than 4095.

To trigger on 4095 you can use:
dwf.FDwfDigitalInTriggerSet(hdwf, c_int(0), c_int(0xFFF), c_int(0), c_int(0))

To trigger on 2048-4095:
dwf.FDwfDigitalInTriggerSet(hdwf, c_int(0), c_int(0x800), c_int(0), c_int(0))

To trigger on 3840-4095:
dwf.FDwfDigitalInTriggerSet(hdwf, c_int(0), c_int(0xF00), c_int(0), c_int(0))

[Loic VINET]

Hello Attila,

I tried your solution, but it didn't work for me.

Let me explain what I did:

I have a clock signal from DIO out 24 to DIO in 8, when I trigger with dwf.FDwfDigitalInTriggerSet(hdwf, c_int(0), c_int(0), c_int(1 << 8), c_int(0)), it works.

Now I want to trigger on threshold, that is to say as soon as I have a value greater than 100 for example, since c_int(1 << 8) = c_long(256), I tried dwf.FDwfDigitalInTriggerSet(hdwf, c_int(0), c_int(100),  c_int(0), c_int(0)), but it doesnt trigger.

Do you know why?

Regards

[Loic VINET]

Hello Attila,

I tried your solution, but it didn't work for me.

Let me explain what I did:

I have a clock signal from DIO out 24 to DIO in 8, when I trigger with dwf.FDwfDigitalInTriggerSet(hdwf, c_int(0), c_int(0), c_int(1 << 8), c_int(0)), it works.

Now I want to trigger on threshold, that is to say as soon as I have a value greater than 100 for example, since c_int(1 << 8) = c_long(256), I tried dwf.FDwfDigitalInTriggerSet(hdwf, c_int(0), c_int(100),  c_int(0), c_int(0)), but it doesnt trigger.

one more thing, I am using a 16-bit bus, but I want to trigger only within DIO in  (0 to 11) with a threshold

Is it possible?

Regards

[attila]

Hi @Loic VINET

No. Only fixed trigger bus value trigger is supported, specifying mask for bits that need to be low or high.

By unmasking least significant bits it will trigger on a range. Like here it will trigger on 0x0F?? 3840-4095

[Loic VINET]

 

Well well, it is very annoying

How is it possible I cannot trigger relatively to a threshold.  It is common to do that.

Edited March 14, 2023 by Loic VINET