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View Full Version : ViewPort config-strings for recording a pulsetrain just once



StefanL38
10-11-2011, 07:56 AM
Hi,

I would like to know how the config-strings for ViewPort must be written to do the following:

an IR-receiver creates a pulsetrain when receiving a command of an IR-remote-control.
I want viewport to stay ready to record the pulsetrain and start recording the pulsetrain when the first pulse comes in on IO-pin number 3
Viewport should record the pulsetrain and stop recording after 200 milliseconds. No more datareceiving no more updating of any view.
I want to know the basic setup to do this and how I can configure the sampling-resulotion.

I haven't been able to do this yet. I think this is a major use of a digital storage oscilloscope. So my opinion is that this configuration should be inluded in the samples and in the manual of ViewPort.

best regards

Stefan

MagIO2
10-11-2011, 05:50 PM
Can't help you with the Viewport question, but I have a comment for you because of your other recent threads.

I also experimented with some remote controls a while ago. Some behave different than you might expect. For example there are remote controls which have a flipping bit - flipping a bit with each repeat. Other remote controls send the signal for a few ms and then switch to a much simpler repeat-code.

So, if you really want to have a device that accepts all possible codes and maybe send all possible codes you have to watch more than one periode.

Hanno
10-12-2011, 10:09 AM
Hi Stefan,
Sounds like you just want to set the timescale of the Logic State Analyzer view and set a trigger for pin 3?
Here's a config string from tutorial #1 "Four bit counter":
vp.config(string("lsa:view=io,timescale=1ms,trigger=io[16]r"))
This tells ViewPort that:
- the LSA should view the "io" channel.
- the timescale per division is 1mSec
- that it should trigger on the "r"ising edge of pin 16 of the IO channel.
Once you've captured a trace you zoom in/out or drag the trace to the left/right to see additional detail. You can use QuickSample with up to 4 cogs to sample at configurable timescales up to 80million samples/second. For slower data you can continuously "stream" data across at 2mbsp- that works out to 50ksps at 32bit/sample.
Hanno

Hanno
10-12-2011, 07:05 PM
ViewPort supports "single-shot" triggers as well. Just suffix your trigger configuration string with a "!" like this:
vp.config(string("lsa:view=io,timescale=1ms,trigger=io[16]r!"))
When you're in DSO mode viewing analog instead of digital values, the configuration can look like this:
vp.config(string("dso:view=cntr,timescale=50ms,trigger=cntr>.5,bgnd=yellow"))

Once the trigger has fired, acquisition will stop...
Hanno