Capacitive Touch Not working

[gauravkothari23]

Hi all.
I am designing a Capacitive touch sensor using Cypress CY8CMBR3102 IC.
Have also attached the circuit diagram.
The IC works properly. when any finger is touched to the pad, the LED glows and as soon as the finger is removed the LED goes off, That's perfect.
But when the system is OFF and i keep the finger on the Touch Pad and then i switch ON the system, it does not detects the finger on startup, so i have to remove the finger and place it again, can anybody please let me know what changes have to be made in the circuit for the IC to detect the finger on Startup.

 

[KlausST]

Hi,

Did you check diagnostics?

Klaus

 

[gauravkothari23]

Hi,

Did you check diagnostics?

Klaus

yes, i have tried changing all the setting and configuration using CYpress Easy click software.
but still the things are not working.

 

[danadakk]

There is a stuck sensor register setting ......page 16 datasheet -




Regards, Dana.

 

[KlausST]

Hi,

yes, i have tried changing all the setting and configuration using CYpress Easy click software.

this was not my question.


So diagnostics are enabled....

Then read out the contents (after power up, and when finger touches the sensor) and upload the values of the registers here.


Klaus

 

[gauravkothari23]

There is a stuck sensor register setting ......page 16 datasheet -

View attachment 159329


Regards, Dana.

this is a sensor auto reset feature.
when sensor is being activated for more than estimated time say 5 or 20 seconds, the sensors goes OFF automatically.
but my problem is sensor does not gets activated, when i keep my finger on capsense at OFF state and then when ON the system the capsense does not detect my finger, so i have to remove my finger and place it back on the capsense to get activated.

- - - Updated - - -

Hi,


this was not my question.


So diagnostics are enabled....

Then read out the contents (after power up, and when finger touches the sensor) and upload the values of the registers here.


Klaus

as i am not using any microconroller to communicate with Touch IC using I2C to read out the content, the output pin of touch IC is connected to microcontroller port pin to just detect the touch

 

[KlausST]

Hi,

are you sure the sensor is able to do what you want?
can it properly detect a finger during power up?

There is a good chance that the sensor needs all touch to be released to self-calibrate.

Klaus

 

[gauravkothari23]

Hi,

are you sure the sensor is able to do what you want?

Klaus

No the sensor is not able to do what i exactly need. i need when during power Up, if the finger is kept on the touch pad, it has to detect the finger and send the signal, which its not happening

Hi,
can it properly detect a finger during power up?
Klaus

yes, it detects the finger after the power up, but not if the finger is placed on the touch pad before power up.

 

[FvM]

The device has many configuration features. Did you try to disable automatic threshold and set the finger threshold appropriately?

 

[gauravkothari23]

The device has many configuration features. Did you try to disable automatic threshold and set the finger threshold appropriately?

Yes, i tried disabling automatic threshold, and also tried with different finger threshold. but the things are not working
also tried to change the scan period but still the problem arises

 

[danadakk]

- - - Updated - - -

You are aware of these resources -

https://community.cypress.com/docs/DOC-10616

https://www.cypress.com/documentation/application-notes/an90071-cy8cmbr3xxx-capsense-design-guide


From the manual -




Look at notes in page 52 of manual, 5.1.2.4


Regards, Dana.

 

[KlausST]

Hi,

and: 001-91082_CY8CMBR3xxx_CapSense_Express_Controllers_Registers_TRM.pdf
https://www.cypress.com/file/127221/download

Klaus

 

[danadakk]

If your solution encompasses coding to modify register values be
careful about foot notes on register descriptions. Often there are
interrelated effects on other HW that is described in the foot notes.

Read the fine print carefully.


Regards, Dana.