MSPCAPTDSNCTR: CAPTIVATE EVAL boards and GUI

Hello Harri,

In the SNR tab of the CapTIvate Design Center, you can export all of the SNR information per sensor to a CSV. 

The CapTIvate technology does not measure absolute capacitance, but relative capacitive changes. However, in application you can access the measurement data (raw counts) directly if you desire. See this section wihtin the Software Library UG: 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_library.html#access-element-measurement-data 

Hello Jace,

Thank you. Appreciate your quick response. I did manage to get a CSV file. I will dig in a bit more and get back if I have any queries.

regards

Hari

Hello Jace,

 I am looking at some applications which require me to switch between different operating frequencies for capacitance sensing ( e.g. 10 kHz, 100 kHz, 500 kHz, 1 MHz, 5 MHz, 10 MHz, etc.) (frequency sweep or frequency selection). I found TI chipsets like FDC1004 operating at either single fixed frequency (25 kHz) and FDC2214 offering wide frequencies (10k-10 Mhz) but not switchable using the Sensing solutions GUI (requires hardware design). 

I have a few more questions on the CAPTIVATE boards 

a) What is the operating sensor frequency range? Is this info provided anywhere?

b) If the boards do provide multiple frequency ranges, can this be switched using GUI (captivate design centre)?

Where can I find such info?

Hope to hear from you soon.

regards

Hari

Hello Hari,

CapTIvate can actually automatically sample at up to 4 different frequencies. See function calls here: 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_library.html#sensor-update-routines

Its typically used in conjunction withEMC resistance: 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_library.html#emc

CapTIvate operates at 19MHz and has set dividors for different conversion frequencies. See: 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/Frequency_Divider.html

In general the CapTIvate Design Guide i've been linking to has all the information you need for capacitive touch designs with CapTIvate. 

Thank you Jace. Really helpful! Appreciate it. I wet through the links ane it has improved my understanding substantially

Just have one question. I cannot seem to find any shielding options in Captivate, unlike FDC1004. Any possibilities of active shielding?

Hello Hari,

Most designs can be accomplished with passive shields utilizing different ground pours and hatching. However, you can also see other solutions by searching for "Driven Shield" in the design guide like: 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#proximity-sensor-with-driven-shield 

Thank you Jace. I checked the different frequencies as per your suggestion. I am unable to validate the different frequencies from f/1 to f/128 (16 M Hz to 125 kHz) using an oscilloscope. I connected the terminal, for example, CAP0.0 and ground on FR2676 board to red and black terminals of an oscilloscope. I  varied the frequency divider option to verify. I do see changes in the frequency of the waves but the waveform and frequencies don't match (kHZ only). Am I doing anything wrong?

Hello Hari,

To clarify here, the device is not outputting different frequencies to the capacitive sensors. It  is just adjusting the internal sampling frequency of the CapTIvate peripheral. 

Thank you, Jace. Appreciate all your responses. Immensely enlightening! Will get back when i have more queries. I will close this thread for now.