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LTSpice woes: oscillation and logic controls

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ACharnley

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As much as I love this software I equally hate it.

Working with FETs and voltages I find myself more and more using GPIO's to make decisions, which requires emulating the hysteresis logic they'd contain otherwise LTspice goes into loops. Unless I'm missing a trick I end up doing multiple B source's which reference one another. The approach works but after a while the multiple IF's become a pain (I sometimes have 4!).

Surely there's a better way?!?

Q) Is it possible to set params dynamically?
Q) Is it possible to condense these IF's using standard operators: && ||


Screenshot_2018-09-04_09-05-41.png
 
Does it have emulations of single schmitt triggers such as 74HC14, CD40106 etc?

Depending what you are doing, they may work.
 
Have you tried using the 'A' devices? You can set their parameters (e.g. you can set the Schmitt buffer threshold and hysteresis, so that it behaves like a comparator), but AFAIK you can't set any parameters dynamically.
 
They're in the LTS 'Digital' folder and are primitive ideal gates with 1V logic by default.
 
Don't think that's possible. Try using a pair of gates or switches.
 
alec_t, bingo - that's exactly what I needed.

Now, how to get the schmitt inverse pin to include a deadzone?

The A devices don’t support that functionality. You’ll have to use a combination of A devices.

Maybe use a clock source with a leading and trailing edge detectors. The pulse width of the clock source could then set the “dead” time.

eT
 
Here's one way :
Deadzone.PNG


Param 'on' sets the dead zone between b and d.
 
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