CapSense MBR3 Evaluation Kit - Review

Table of contents

RoadTest: CapSense MBR3 Evaluation Kit

Author: astro27

Creation date:

Evaluation Type: Evaluation Boards

Did you receive all parts the manufacturer stated would be included in the package?: True

What other parts do you consider comparable to this product?:

What were the biggest problems encountered?: The biggest problem i encountered was the fact that no examples were running on my system saying the project is not a valid project file for the EZclick software which was due to the fact that i had administrator permission problem. So i uninstalled the software and reinstalled to get it running. Else everything was nice and fine.

Detailed Review:

Hello all

This is my first roadtest review and I hope it goes well. I received the kit on 4th july.

Included items :

  • CY3280-MBR3 EVK with a 2-mm overlay
  • One additional overlay of 1-mm thickness
  • A to Mini-B USB cable
  • Water dropper
  • Raspberry pi

  Introduction 

The CY8CMBR3 series is the latest addition to the register-configurable CapSense Mechanical

Button Replacement (MBR) family of solutions. The CY8CMBR3 family of controllers enables

you to quickly and easily add capacitive touch sensing to your user interface.

CY3280-MBR3 offers the best features of Cypress’ CapSense in a small

package that is easy to implement and configure. Coupled with the Capacitive Sigma Delta PLUS

(CSD PLUS) sensing algorithm and the patented SmartSense Auto-Tuning feature, the

CY8CMBR3xxx controller provides a robust capacitive sensing solution, with up to 16 CapSense inputs.

SmartSense Auto-Tuning has the following advantages:

Reduces design effort by eliminating manual tuning

Adapts to variations in PCB, overlay, paint, and manufacturing that degrade touch-sensing performance

Eliminates manual tuning in production

Adapts to changes in the system environment due to noise

Allows a platform design approach with different overlays, button shapes, and trace lengths

 

Setting up:

  1. 1. Install EVK software from www.cypress.com
  2. 2. Power up the device and get the drivers installed .
  3. 3. Find the Com port.
  4. 4. Open Ezclick and run or create projects.

The evaluation kit has a lot of very good and interesting features. One of them is the SmartSense

auto-tuning capability of the device. The SmartSense Auto-Tuning provides some very cool features. It is one of the best thing about this kit for me. It readily adapts to variations in PCB, overlay, paint, and manufacturing that degrade touch-sensing performance. It also eliminates production-related manual tuning,adapts to changes in system environment due to noise sources, allows a platform design approach with different overlays, button shapes, and trace lengths. The whole setup as to how to vary the parasitic capacitance is illustrated in the capsense mbr3 user guide.

Capacitance variations :

The capacitance can be varied in the follwing three ways :

  • Using short and long traces on the BTN4

  • Using 10 and 15 pf external caps on BTN2

   

  • Using 1 mm overlay provided in the kit

 

Here are some more graphs on normal touches . This one depicts diff count vs finger threshold. At the default value of 128 the capsense worked accurately. But when I tried to increase the finger threshold from 128 to higher values the kit detected some false detection below the finger threshold.

This is the graph for the raw count vs the base line. The touches can be easily identified.

PROXIMITY DETECTION

The proximity sensor is one more interesting feature of the kit. It can be easily configured in the Ezclick software. There are two proximity sensors. These can detect proximity and proximity  finger touches. According to the application required the proximity and finger threshold can help in detecting proximity and finger. I had enabled the buzzer for finger touches so first proximity was detected in the BUTTON STATUS and the buzzer is sounded when finger touch is detected only after the proximity finger threshold is crossed.

WATER TOLERANCE :

The water tolerance feature can be easily configured by opening the water tolerance project. With the guard sensor and shield electrode in the device turned on the device is operated as per the requirements.

HOST INTERRUPT :

This can be easily configured in the EZ click software. I firstly configured the J15 jumper to A combination so that cs15 is allowed for host interrupt pin in global config tab.

Current Measurement :

The low power needed to operate the device is one of the attractive features of the device. The total current consumption of the whole MBR3 kit varies from 60 to 90 milliamps highest when all the leds and proximity sensors were on. This can be tested by connecting a multimeter across the jumper J11. The CY8CMBR3116 Device current goes not more than 1.5 milliamps in my test. This can be tested by connecting a multimeter across the jumper J12.


Other features include : The sensitivity of the buttons can be increased to get a more precise touch . this helps in eliminating false touches.

 

FSS (flanking sensor suppression) : Eliminates false touches by distinguishing between signals

from closely spaced buttons. This can be activated in capsense sensor configuration tab. If you touch multiple buttons with this feature on it will take only the first one.


Auto reset : this feature resets the led status if the button is still on after the time indicated in the autoreset period. Also by activating the use led duration box in global config tab the leds remain on after the button is released with the duration as indicated in the led duration box.


Active and inactive duty cycles are a very important feature . This allows the device to work and be visible in the nights also . the inactive duty gives the amount of brightness when no button is touched. In the proximity sensor mode these leds can be turned off completely and these become slightly dim that is as indicated in the inactive duty cycle when the proximity sensor senses somebody around. This can be done by checking the wakeup sensor in the capsense sensor configuration tab. This also helps in low power consumption of the device.

 

Buzzer : It can be activated in the global config tab with a specified frequency and duration of sound.


Conclusion :

The build of the kit is very good. The pcb is very well laid out and nice. I was not knowing of cypress as a major silicon company earlier may be due to less visibility. But after working on this eval kit i consider it one of the best player in the market. At least for me I liked the whole pcb layout, software, accessories of the kit and consider it much better than any other company gives at this price. The ease of configuring the kit, all the accessories being included, very good documentation, jumpers for measuring current are some of its plusses. On the negative side I feel the only problem with the kit is the placement of the trace button for testing purpose but in actual applications this placement is also well made.


I havent added anything of my project. I was thinking of using the host interrupt on the capsense to interrupt the raspberry pi. For enabling the host interrupt

1. first the combination of the  J15 jumper to 'A'.

2.Then we have to enable the host interrupt in the global config tab.


I was thinking to add the raspberry pi gpio interrupt libraries in the LXterminal and then using interrupts on capsense to interrupt the raspberry pi to take photos when the capsense buttons are touched. This i will be adding to this review or into a blog as and when i finish it.

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