Triggering and the OptaScope

r2d2_bot

·· I finished the Asynchronous chapter in 'Understanding Signals' and was viewing two channels with the same exact data with the OptaScope V 4.0.0.· When I had my triggering set for channel 1, the start bit of the signal for channel 1 was aligned with the middle vertical gridline, but the start bit for channel 2 was offset from the middle vertical line.· The situation was reversed when I switched the trigger from channel 1 to channel 2.· I also noticed when I set the trigger settings for one channel, there were set for the other channel as well.
·· My questions are:
·· > Can you have independent trigger settings for each channel, if so how?
·· > Why won't both identical signals line up the same in the window?· It acts as if only one channel can be triggered at a time.· Is this true?
·· > I've attached a png file when I have the trigger channel selected for each channel.· Is there any way I can have both channels line up at the same time?

Thanks!

[noparse][[/noparse]Tim]

Chris Savage

Hello,

There is only one Trigger input. This is typical of most common scopes. Even our Tek Scopes here have only a single external trigger input or can be triggered from one or the other channel. It appears that, while your signals may be identical they are being sent one after the other, which indicates they are from different I/O pins. Is this the case?

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Chris Savage
Parallax Tech Support

r2d2_bot

Chris

·· Yep, guilty as charged!· I have the one signal on port 15 and the other on port 14.· I placed both channels on the same port and the delay went away.· I've rarely used multiple channels on a scope before, so never much thought about triggering across multiple channels.· I measured the delay between the channels and it is around 1.6ms.· I'm assuming this would be the amount of time between the two program statements?

[noparse][[/noparse]Tim]

Chris Savage (Parallax) said...
Hello,

There is only one Trigger input. This is typical of most common scopes. Even our Tek Scopes here have only a single external trigger input or can be triggered from one or the other channel. It appears that, while your signals may be identical they are being sent one after the other, which indicates they are from different I/O pins. Is this the case?

Chris Savage

Tim,

You are correct…It includes the load time for the next instruction, but the delay also includes the time it takes to complete the previous instruction.

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Chris Savage
Parallax Tech Support