MSP430FR2633: MSP430FR2633 - Need of the Ground Guard around the Custom Board for buttons and slider

Hello Sanath,

The guard ground is not necessarily the issue here.  How many elements do you have in your slider and are the 2 end elements tied together?

Hi Eddie,

We have 4 elements and Yes our 2 end elements are tied together .we have done it with reference to the development kit hardware.

We are using a acrylic material on top of the slider which is about 4mm .

Even the same flickering of slider occurs  occasionally when we put the acrylic on top of the board but it's not there  when we use the bare board.we attach the acrylic using gum on top of the board.we have kept the sensitivity as needed for acrylic and the touch is working fine.

Regards

Sanath Rai

Sanath,

Since you have flickering, then 1 or more of your elements must have noise that is exceeding the touch threshold.  This gets detected and the slider algorithm tries to process the position.  Can you provide your Captivate .ser file?

Hi Eddie,

Below i have attached the .ser file for the slider and button.

How can be the Noise reduced on Individual Elements?

How and from where does the noise is generated?

Regards

Sanath

Hi Eddie,

there is some issue in attaching the .ser file to the forum.

Regards

Sanath

Can you try changing the file extension to something other than .ser to see if it accepts that?

CaptivateDesignCenter.txt

Above is my .ser file in txt format.

Regards

Sanath

Hi Eddie,

The reason we have set the conversion count high is we are not able to find the valid touch on acrylic material of 4mm.when conversion count is set to 1750 i am able to find the touch on acrylic material.

Regards

Sanath

Hi Eddie,

One small update about the thickness of acrylic material its not 4mm its 6mm.

we can see the valid touch at conversion gain value at 1750.

Can you give me exact values of gain and count for 6mm material sensitivity .

Regards

Sanath

Hi Sanath,

Sorry for the delayed response.  Were you able to resolve the issue?  You can also reference the tuning sensors section of the Captivate technology guide below.

http://software-dl.ti.com/msp430/msp430_public_sw/mcu/msp430/CapTIvate_Design_Center/latest/exports/docs/users_guide/html/CapTIvate_Technology_Guide_html/markdown/ch_workshop.html#part-2-tuning-sensors 

Hi Eddie,

I will look into the link provided.

We still have the flickering problem of the slider.

We have understood that it's because of the sensitivity as we have set the touch threshold and proximity threshold very high( 255) value as only for that we are able to get the valid touch on slider on the acrylic material of 6mm .but even in design center i can see the slider flickering continuosly .

We have made some changes in our PCB and relaunched it.we need to check in our new board.

Can you review our PCB design layout ?

Regards

Sanath

Sanath,

Yes, I can review your PCB.  If you want to send the PCB privately, I can send you a connection request where you can send directly to me.  If the PCB does not need to be private, you can attach here.

Hi Eddie,

Thank you,

In this version of our PCB we had a copper cover on the electrode which made the sensitivity less and on acrylic i couldn't tune it .

Now we had launched a new version of PCB and i was able to tune it and have kept the slider sensitivity very less.

Now we have kept it under observation to see whether the flickering will reocurre or not?

I will let you know the update here.

Thank you

Regards

Sanath Rai