Unexpected behavior on JP5

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Unexpected behavior on JP5

Post by cyprian21 » Mon Mar 29, 2021 10:02 pm

Hi there,

I recently got a MPG2 – Control Pendant from Automation Technology.

https://www.automationtechnologiesinc.c ... g2-pendant

I have been following the implementation from this post here:

and linked articles on the Dynomotion Wiki here:
https://www.dynomotion.com/wiki/index.p ... _Interface

I am trying to implement this MPG on JP5.

However, even before hooking up the MPG, I noticed that when Pin 1 is driven high (with 5V+), Pin 2 seems to be producing a 1.4V+ output even though there is a 1K pull down resistor. I have 8 resistors because I am planning to pull down all the JP5 pins eventually, here I am just starting with the first two pins. You can see this on the voltmeter. I am measuring the voltage on Pin 2 while Pin 1 has 5V+ applied.

You can see that in the first picture I am not driving Pin 1 (Pin 2 is reading 0V+) and in the second picture I am driving Pin 1 and strangely Pin 2 is reading 1.4V+.

Any ideas on how I can resolve this?

Thank you,
I am running Kmotion/Kflop Version 4.35e.
not driving high
driving high
closeup hookup: power and ground from Kflop 5V+

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Re: Unexpected behavior on JP5

Post by TomKerekes » Mon Mar 29, 2021 11:54 pm

Hi Cyprian,

KFLOP IO is 3.3V LVTTL. Even though 5V tolerant pins will not be damaged with 5V avoid driving KFLOP inputs above 3.8V. If you do because of a quirk in the way the inputs are protection diode clamped together in pairs, some leakage current will leak to the other pair pin. In the post notice the switches are switched to 3.3V not 5V. 5V is only used to light the LED in the MPG.


Tom Kerekes
Dynomotion, Inc.

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