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4200-L, Power-efficient GPIO configuration (IRQ+Wake-support) | Cypress Semiconductor

4200-L, Power-efficient GPIO configuration (IRQ+Wake-support)

Summary: 3 Replies, Latest post by Bob Marlowe on 21 Sep 2016 12:43 AM PDT
Verified Answers: 0
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dav01's picture
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22 posts

Hi,

Using CY8C4247BZI-L479, I assume it's possible

I'm planning to use 56 gpio inputs from various buttons & external signals.
Requirements:

  • any gpio must be able to wake from "deep sleep" (preferably hibernate and stop-mode as well)
  • gpio's should be completely interrupt-driven in run-time (as well as the requirement from sleep above)

I need some input on best practice and if someone knows how the "Interrupt Source Multiplexer" works behind the scenes, in sleep and if it draws any extra/considerable amount of power.

 

best david

 

user_1377889's picture
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10719 posts

Have you already seen this appnote?

 

Bob

dav01's picture
User
22 posts

Hi Bob,

That app-note is great, amazingly detailed.

 

I'll try and measure a bit, what I'm not sure about regardless of mode, deep-sleep/hibernate, is when say having all GPIO's set to inputs, wake on falling-edge (i.e. button shorts to gnd when pressed with internal pull-up on the gpio)
vs.
just one gpio doing the same. Would that make a difference in the overall power consumption.

Related,
I see in most app-notes they state wake-irq on rising-edge. Also doable if changing the button scheme from common gnd to all being pulled together say 1.8V and have all gpio's have a pull-down instead. Pros/cons? 

best David

user_1377889's picture
User
10719 posts

I think even defining interrupt on both edges for an input pin will not have much influence on power consumption, but you may try out.

I would always recommend to use pullups, so you do not have power at the (external, accessible, vulnerable) switches.

 

Bob

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