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MSP430FR5889: MSP430FR5889

Part Number: MSP430FR5889
Other Parts Discussed in Thread: MSP430FR2633

Sir,

This is in continuation to our conversation on CAP SENSE of MSP430FR5889.Now we are able to sense the cap sense switches.But the problem is the thickness of the OVERLAY.

If the overlay is about one mm, it is not sensing.But our application is a three mm acrylic sheet.

What should we do to have a 3 mm OVERLAY to give a reliable switch operating result.If any specific guideline are available to have the required 3 mm sensitivity

we can try that.

  • Hello Vijeth,

    You will need to increase the sensitivity of captouch application in order to sense through a thick overlay. For the fRO method that the MSP430FR5889 uses, you have two options for this. You can either a) increase gate time or b) increase system clock resolution (higher speed). Please note that by increasing your gate time that you will see decrease in response time as your scan rate lengthens. Please also note that grounding schemes on your board can be affecting your sensitivity as well.

    Have you seen our CapTIvate enabled devices such as MSP430FR2633? These devices are specifically built for capacitive touch solutions and allow more extensive tuning to increase sensitivity within SW for your application.
  • Sir,

    Thanks for your reply.

    But our application demands 128kb memory with 12 bit adc.Is there any in TI FAMILY with 128kb memory,12 bit ADC and captivate feature.

    Regards

    VTC

  • Hello Vijeth,

    Currently we do not offer a CapTIvate device with that much memory. Please see comments above about increasing sensitivity for the fRO based Captouch library. In addition, I also encourage you to look at the Best Practices within the CapTIvate Technology Guide for how to handle overlays as well as how grounding will affect your sensitivity. As the name implies, the CapTIvate Design Guide is written for CapTIvate devices; however, the Best Practices section applies to capacitive touch based applications.

    software-dl.ti.com/.../ch_design.html