MSP430FR2672: Cap 0.0 pin noise immunity

Hi Astro,

I'm not aware of any difference in CAP0.0's noise performance. Would you be willing to share some information about your layout? Is CAP0.0 close to any switching or RF components?

Also, have you looked through the capTIvate noise immunity guide?

https://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_design_guide.html#noise-immunity-hardware-check-list

Regards,

Evan

Hi, Evan

The LED is controlled by the pin adjacent to CAP0.0.

Is it possible that the control of this LED is involved?

Thanks,

Astro

Hi, Evan

I have one additional question.
When I select the device "MSP430FR2672TRHB" on the Design Center, "Dynamic Threshold Adjustment" does not appear on the Design Center. Does it mean that MSP430FR2672TRHB is not supported? Is it related to the CapTIvate generation (MSP430FR2672TRHB is GEN2)?

Thanks,

Astro

Hi, Evan

Do you have any update?

Thanks,

Hi Astro,

Apologies for the delay, I was out last week. I'm looking into this and will get back to you by tomorrow.

Regards,

Evan 

Hi Astro,

Can you share a little bit more about your application? Is it battery powered or mains powered? How are you testing you design against noise immunity? 

Does the errant behavior change if the LED is on versus off? Can you review this snippet from the CapTIvate Design Guide: (under Best Practices > Common Layout Considerations > LEDs/LED backlighting)

If you are driving LEDs with using a HiZ state than you may need a capacitor as shown in the figure.

Also, do the LED (or other) traces run near the CAP00 traces? If so it could be possible that those traces are capacitively coupled which could cause problems for capacitive sensing. The capTIvate design guide has information about trace separation. See below.

As far as your other question:

Conor said:

When I select the device "MSP430FR2672TRHB" on the Design Center, "Dynamic Threshold Adjustment" does not appear on the Design Center. Does it mean that MSP430FR2672TRHB is not supported? Is it related to the CapTIvate generation (MSP430FR2672TRHB is GEN2)?

You are correct. 2672 is a GEN2 device. The GEN2 devices have an updated feature set compare to GEN1. Some features that were implemented in software have been added as hardware features.

Regards,

Evan

Hi, Evan

As a measure to change the sensitivity depending on the lighting of the LED, a 1000pF capacitor was added in parallel with the LED.
The place where the capacitor was added and the place where the erroneous reaction occurred this time are the same.
Do you have any views on the relationship between the addition of capacitors and false reactions?

Thanks,

Astro

I don't think that should be a problem. Can you share a bit of your layout close to CAP0.0 and the led?

Regards,

Evan

Evan

Thank you for your reply.
Is it possible to exchange private messages as the layout contains sensitive information?

Astro

Sounds good.