Filter button noise on sleep

Tip / Sign in to post questions, reply, level up, and achieve exciting badges. Know more

cross mob
lock attach
Attachments are accessible only for community members.
TamirM
Level 2
Level 2
25 sign-ins First like given 10 questions asked

I have a power button which cause interrupt and wakesup the system from Deep Sleep.

I would like to add, even only when the system is on (not a sleep),  sort kind of filter, Debouncer or even just the D-FF the filter noise.

the problem is that those components require a clock and when I tried to add it even with Control Register which is initialized to transfer the signal from the

0 Likes
1 Solution
Len_CONSULTRON
Level 9
Level 9
Beta tester 500 solutions authored 1000 replies posted

Tamir,

When you are in Deep Sleep mode, the clocks are turned off except for the LCO.  Additionally the UDB blocks are turned off as well.   Having these elements on would consume significant current <100uA but > 10uA.

The HW RC filter mentioned by Ganesh is a good solution.

Len
"Engineering is an Art. The Art of Compromise."

View solution in original post

0 Likes
5 Replies
VenkataD_41
Moderator
Moderator
Moderator
750 replies posted 500 replies posted 250 solutions authored

Hi,

I guess some part of the statement is missing here: "the problem is that those components require a clock and when I tried to add it even with Control Register which is initialized to transfer the signal from the"

You can use the Debounce component if your device supports UDBs. Please go through the project from the link below:

https://www.cypress.com/documentation/code-examples/ce224719-psoc-4-debouncer-and-glitch-filter

If your end application has enough place on the PCB, you can connect a simple RC filter on the PCB that sufficiently filters the noise.

Please update if you need more information.

Thanks

Ganesh

0 Likes
Len_CONSULTRON
Level 9
Level 9
Beta tester 500 solutions authored 1000 replies posted

Tamir,

When you are in Deep Sleep mode, the clocks are turned off except for the LCO.  Additionally the UDB blocks are turned off as well.   Having these elements on would consume significant current <100uA but > 10uA.

The HW RC filter mentioned by Ganesh is a good solution.

Len
"Engineering is an Art. The Art of Compromise."
0 Likes
TamirM
Level 2
Level 2
25 sign-ins First like given 10 questions asked

Hi,

thanks for the reply.

i have tried the debounce but then the interrupt isn't being triggered by the power button when the system is on deep sleep mode

0 Likes

Tamir,

In Deep Sleep (DS) mode, only certain input Pins are able to wakeup the CPU.

See section:

3.3 Low-Voltage Interrupts in PSoC Sleep Mode

Additionally the DFF you are using is functionally disabled in DS mode.

See the following link:

https://www.cypress.com/documentation/application-notes/an77900-psoc-3-and-psoc-5lp-low-power-modes-...

Len
"Engineering is an Art. The Art of Compromise."
0 Likes
TamirM
Level 2
Level 2
25 sign-ins First like given 10 questions asked

Thanks.

Unfortunately, it's impossible for me to add HW RC Filter (existing boards already at the costumer), I have tried to think of a way to workaround it.

I now understand it's probably impossible. 

0 Likes