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PSoC™ 5, 3 & 1 Forum Discussions

Anonymous
Not applicable

Hi there - first time poster. I'm using a 68-QFN part from the CY8C58LP family.

   

I would like to use P12[7] as a rising-edge triggered interrupt. This is an SIO pin whose corresponding bank voltage (VDDIO1) is 3.3V. The source driving this pin is a digital 1.8V. 

   

What I would like to do is use a Vref for the SIO input threshold, and configure the Vref component to Vccd (1.8V SIO Only). 

   

My question is - when using a Vref as an SIO input threshold, what are the relative Vih and Vil voltages?

   

The "Pin" component datasheet (http://www.cypress.com/file/137401/download) lists on page 31 a few Vih/Vil settings but the GPIO values listed are relative to the VDDIO voltage. If I'm using a reference voltage Vref (instead of the CMOS default), what values can I expect?

   

Thanks in advance -

   

Parker

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Anonymous
Not applicable

I think I may have answered my own question -- the "SIO Tips and Tricks in PSoC® 3 / PSoC 5LP" doc says that when using a threshold other than CMOS/LVTTL that this qualifies as differential input, and not GPIO as I thought mistakenly. So - the Vih and Vil are the SIO reference +/- 0.2V. 

   

So, I think what I actually want to do is set the threshold to 0.5*Vref (which would be 0.9V) and then Vil-Vih are 0.7-1.1V.

   

Can someone confirm?

   

Thanks!

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Anonymous
Not applicable

I think I may have answered my own question -- the "SIO Tips and Tricks in PSoC® 3 / PSoC 5LP" doc says that when using a threshold other than CMOS/LVTTL that this qualifies as differential input, and not GPIO as I thought mistakenly. So - the Vih and Vil are the SIO reference +/- 0.2V. 

   

So, I think what I actually want to do is set the threshold to 0.5*Vref (which would be 0.9V) and then Vil-Vih are 0.7-1.1V.

   

Can someone confirm?

   

Thanks!

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RoBO_1287886
Level 4
Level 4
25 replies posted 10 replies posted 10 sign-ins

pmartin,

   

You are right into the pin configuration of the SIO : you can use a threshold of Vref or 0.5*Vref (it's not the case for a basic GPIO)

   

The Vref could be set into your TopDesign. This value can be the output of VDAC or the internal Vref 1024V.

   

 - Vih range : your selected threshold to VCCIO

   

 - Vil range : 0V to your selected threshold

   

 

   

yours,

   

rob1

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