Pulse Width trigger problem.

Forum for discussing PicoScope version 6 (non-automotive version)
Post Reply
jswanson
Active User
Active User
Posts: 14
Joined: Wed Apr 05, 2006 8:07 pm

Pulse Width trigger problem.

Post by jswanson »

Hi,
PicoScope® 6 - PC Oscilloscope software version: 6.9.14.16
Model: PicoScope 2205 MSO
Firmware Version: 1.3.3.0 / 0.2.2.0

Trying to get the pulse width trigger to work, but it triggers all the time just as if in Simple Edge mode. Here are the settings attached.

This happened once before and it was specific to the MSO apparently. It was fixed but now it's back again.

Thanks,

Jeremy.
Attachments
Settings
Settings

jswanson
Active User
Active User
Posts: 14
Joined: Wed Apr 05, 2006 8:07 pm

Re: Pulse Width trigger problem.

Post by jswanson »

Anyone from Pico tried this yet? Can you confirm it is a problem?

Hitesh

Re: Pulse Width trigger problem.

Post by Hitesh »

Hi jswanson,

I've tested a setup here with a square wave (500mHz or slower, 5Vpp with +2.5V offset) using a version of PicoScope 6 that will be released shortly and can confirm that the pulse width trigger does work with the condition specified.
Example of Pulse Width Trigger
Example of Pulse Width Trigger
The new version will be available via our Software Downloads page (http://www.picotech.com/software.html) or you will receive an alert via the PicoScope 6 software if you have enabled the appropriate option in the Updates tab of the Preferences dialog.

Regards,

jswanson
Active User
Active User
Posts: 14
Joined: Wed Apr 05, 2006 8:07 pm

Re: Pulse Width trigger problem.

Post by jswanson »

Hi Hitesh,

I put 1s in the original as I was trying to see what values would work (nothing did).

Here is the waveform I am trying to trigger. I have triggered on this in the past, so I'm guessing it is a problem with the current version?
Attachments
Serial Break at 250kbps
Serial Break at 250kbps

Hitesh

Re: Pulse Width trigger problem.

Post by Hitesh »

Hi jswanson,

I believe that is correct - an issue was found in the driver which has been fixed.

The new release of PicoScope 6 incorporating the fixed driver will be available shortly.

Regards,

Lotharyx
Newbie
Posts: 0
Joined: Tue Dec 02, 2014 9:55 pm

Re: Pulse Width trigger problem.

Post by Lotharyx »

Hi, I am having a pulse-width trigger problem as well, with channel D on a Pico 3405A.

If I use the onboard signal generator maxed at a 2V 1 MHz square wave fed into channel A, I can see the triggering stop if I increase the pulse width beyond 500ns. Just fine.

Unfortunately, I am trying to observe a faster signal on channel D, and it only triggers when the pulse width is set to 0 (zero).

I am trying to observe a serial binary signal which is sometimes a single high bit, and sometimes two high bits in a row, operating at around 3 MHz. In other words, sometimes the pulse is one clock cycle (about 300 ns), and sometimes it is two cycles (about 600 ns). Here are some images to help explain.

First there is short_pulse.png, which shows the short pulse of about 300 ns.
The shorter pulse
The shorter pulse
Then there is long_pulse.png, showing the longer pulse, about 600 ns.
The longer pulse
The longer pulse
Finally, there is no_trigger_4ns.png, showing how the trigger doesn't occur even with a "greater than 4ns" setting.
Pulse width trigger set to greater than 4ns, no trigger occurs
Pulse width trigger set to greater than 4ns, no trigger occurs
I expect that I should be able to set to pulse width triggering around "greater than 500 ns" and the trigger occur only on the longer pulse. Unfortunately the trigger never occurs. There is a lot of ringing on the signal, but that ringing is all above the trigger threshold and shouldn't be a problem. I also tried a window pulse width, setting "dwell inside" to cover the entire ringing amplitude, and it doesn't work either. Is help available for this issue?

Hitesh

Re: Pulse Width trigger problem.

Post by Hitesh »

Hi Lotharyx,

There have been some issues with pulse width triggering in relation to the PicoScope 3400 devices which have recently been fixed and verified.

The fixes should appear in the next release (no timescales at present) after PicoScope 6.10.6.

In the meantime, you could try using Channels B or C for your trigger channel. Other than Channels A and D are you using any other channels?

Regards,

Lotharyx
Newbie
Posts: 0
Joined: Tue Dec 02, 2014 9:55 pm

Re: Pulse Width trigger problem.

Post by Lotharyx »

Hi, and thanks for the rapid engagement. I really appreciate that.

It seems like using another channel on the same signal allows the pulse width trigger mode to function correctly, so perhaps the problem is unique to channel D.

I have moved on to other modes of testing which do not rely on the pulse width triggering, but I still look forward to PicoScope software and driver updates.

HMD
Newbie
Posts: 0
Joined: Mon Jul 06, 2015 10:00 am

Re: Pulse Width trigger problem.

Post by HMD »

Hello,

I found a(nother) bug in the Advanced Trigger Menu “Pulse Width” for digital inputs (D1/D0) . If I try to trigger for a Pulse Width greater than 20 ms on a digital input (D1). The Oscilloscope triggers always.
But the pulse width is less than 5ms.
My digital signal channel settings are correct: (Signal is TTL 3.3V high)
For analog signals e.g. A/B everything works fine.

SW versions: PicoScope® 6 - PC Oscilloscope software version: 6.11.4.929 and 6.10.16.2

Hitesh

Re: Pulse Width trigger problem.

Post by Hitesh »

Hi HMD,

There was an issue relating to pulse width triggering on digital channels that was reported and fixed recently. This should be available via the next version of PicoScope 6.11 Beta.

If you have a PicoScope 6 settings file corresponding to the trigger setup, please post it here or send to support@picotech.com and we can take a look.

Regards,

Post Reply