Author Topic: [Solved] Touch sensor MCU selection  (Read 1289 times)

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Offline blueskullTopic starter

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[Solved] Touch sensor MCU selection
« on: March 09, 2017, 07:32:20 pm »
Hi all. I'm working on a digital gadget that requires user interface, particularly, physical buttons and touch buttons.
Is there any suggestion on which MCU to use to implement touch sensing?
I will also need PWM, I2C slave and ADC features, so dedicated touch sensors won't work. UART is also welcomed for debugging purposes.

I'm currently looking at MSP430 CapTIva, UFM8SB1 and PSoC 4000, I've used neither, and I can learn to use either.
The chosen technology must have very small package, 0.4mm/0.5mm pitch WLCSP first. QFN up to 4mm*4mm is acceptable, WLCSP less than 0.4mm is not an option.

I need moisture rejection, water spill rejection is not required. Wake up on touch is not needed. Operating voltage: 3.1V (3.2V Li-ion cutoff minus 0.1V LDO drop-out).

Thanks in advance.

Solved. PSoC4200 selected.
« Last Edit: March 09, 2017, 11:40:25 pm by blueskull »
 

Offline amitchell

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Re: Toush sensor MCU selection
« Reply #1 on: March 09, 2017, 07:36:35 pm »
Cypress seams to be the leader for touch. I am using the PSoC 4000S, moved from the Atmel Atmega328PB.

The 4000S is the newest generation of touch. I am running at 1.8v

I find the Cypress support to be better and I can get samples from them.
 
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Offline timb

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Re: Toush sensor MCU selection
« Reply #2 on: March 09, 2017, 08:56:36 pm »
Yes, the PSoC 4200S series is very good when it comes to CapTouch MCUs. They have replaced the MSP430 as my go to micros for capacitive sensing. The S generation support some pretty advanced features, including CSX sensing (versus CSD), guard nodes, water proofing, support for button matrices, proximity, etc.

Well worth looking into.
Any sufficiently advanced technology is indistinguishable from magic; e.g., Cheez Whiz, Hot Dogs and RF.
 
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Offline Dielectric

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Re: Toush sensor MCU selection
« Reply #3 on: March 09, 2017, 10:42:47 pm »
If you need an ADC, use the PSoC4xxxS series.  The one in the non-S series is harder to use.  The S family also has UARTs and more PWMs, all you get in 4000 is an I2C-slave and one TCPWM block.  If you go with a 4100S, you can get an additional "real" SAR ADC instead of the CSD-ADC in the 4000S, which is nice.

Plenty of package options, 24-QFN and 25-WLCSP are the smallest.  Then 32-QFN and 35-WLCSP.

For the moisture rejection, you can either use CSD (self capacitance) mode with shield, or try the CSX mode (mutual capacitance) which has some natural moisture rejection.  You're smart enough to figure the rest out.
 
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