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PSoC 4 MCU

BhSa_4078721
New Contributor

Hi,

I am want to implement the below requirement :

12 CapSense buttons

12 leds

1 I2C

2 GPIO

Maximum current consumption would be 20mA & it should operate in deep sleep mode with min 5uA current consumption. Capsense button press should wake up the device from deep sleep.

Please help me to select the ultra low power controller part fulfilling the above requirement with low cost.

Thanks in advance....

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1 Solution
BragadeeshV
Moderator
Moderator

Hi BhSa_4078721​,

We recommend you to go with PSoC 4000 S device for your requirement

PSoC® 4: PSOC 4000S Family Datasheet PROGRAMMABLE SYSTEM-ON-CHIP (PSOC) (cypress.com)

It is not possible to use capsense to wake up the device from deep sleep. CapSense block is not active when the device is in deep sleep and hence CapSense interrupt can not wake up the device from deep sleep. Therefore, you need to have another wakeup source such as WDT to periodically wakeup the device from deep sleep and then perform a capsense scan to check if there was a touch or not.

Please refer

Code example: https://www.cypress.com/documentation/code-examples/ce210291-psoc-4-capsense-one-button

App note:  https://www.cypress.com/documentation/application-notes/an210998-psoc-4-low-power-capsense-design

Regards,

Bragadeesh

Regards,
Bragadeesh

View solution in original post

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7 Replies
BragadeeshV
Moderator
Moderator

Hi BhSa_4078721​,

We recommend you to go with PSoC 4000 S device for your requirement

PSoC® 4: PSOC 4000S Family Datasheet PROGRAMMABLE SYSTEM-ON-CHIP (PSOC) (cypress.com)

It is not possible to use capsense to wake up the device from deep sleep. CapSense block is not active when the device is in deep sleep and hence CapSense interrupt can not wake up the device from deep sleep. Therefore, you need to have another wakeup source such as WDT to periodically wakeup the device from deep sleep and then perform a capsense scan to check if there was a touch or not.

Please refer

Code example: https://www.cypress.com/documentation/code-examples/ce210291-psoc-4-capsense-one-button

App note:  https://www.cypress.com/documentation/application-notes/an210998-psoc-4-low-power-capsense-design

Regards,

Bragadeesh

Regards,
Bragadeesh

View solution in original post

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BhSa_4078721
New Contributor

Thanks for the reply,

Hi Bragadeesh,

I tested the sample code example above, in that I changed only the Controller all other remains same.

In that code I Got Current  35 micro-ampere on Multimeter but ideally it should get the 6 micro-ampere in deep sleep mode.

I used the customized capsense board and only assembled the Bypass capacitor(two pairs ) & Capsense Resistors(560 ohm) on the board.

How to reduce the current upto the 5 or 6 Micro-Ampere

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BragadeeshV
Moderator
Moderator

Hi BhSa_4078721​,

Is 35 uA the instantaneous current consumption or is it the average power consumption?

Regards,

Bragadeesh

Regards,
Bragadeesh
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BhSa_4078721
New Contributor

Yes, it is average current consumption.

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BiBi_1928986
Contributor II

Hello BhSa.

Here's a good article on measuring low current in uA range.

Current Ranger | LowPowerLab   Watch the video.

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odissey1
Honored Contributor II

BhSa,

Check this blog for PSoC low-power current consumption measurement

https://iotexpert.com/psoc-4200m-low-power-with-wdts/

And here is a must-read info on PSoC 4 low-power operation

PSoC 4 Low-Power Modes and Power Reduction ... - Cypress Semiconductor

Don't forget to configure all unused GPIOs to Analog HI-Z unless there is a specific reason to use a different drive mode - digital pins are leaky even in the HiZ mode!

/odissey1

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Len_CONSULTRON
Honored Contributor II

BhSa,

Do you have a scope plot of the current?  

Are you using a scope or meter for the measurement?  Note:  Many meters perform a averaging.  Some can perform peak-n-hold measurements.

Suggestion:

To determine if the 30uA is during low power mode, turn off the WDT that is the wakeup event.   This should prevent the wakeup for the test and should give you an indication of the actual low power mode you are in.

I have found that in design for very low-power modes that external parasitics can have a big impacted on the current at such low levels.  Make sure your design doesn't have any resistive paths that may cause unexpected leakage. 

At VDD = 5V it only takes 1M ohm to dissipate 5uA of current.

Len

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