RoadTest: CapSense MBR3 Evaluation Kit
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?: MSP430 Launchpad + Capacitive Touch Booster Pack
What were the biggest problems encountered?: At first, pin mapping between CY8CMBR3116 and CY3280-MBR3 EVK was a little confusing but after you getting familiar with the kit is fine.
I choose to test this kit because I build a night light with clock and changeable light color and intensity for my daughter and I don't want to use mechanical buttons to adjust the device settings. Before I found CapSense MBR3 kit, I tried to use for this task a MSP430 Launchpad plus Capacitive Touch Booster Pack. It basically worked ok for what it is but tuning and integration with the rest of target device is harder and offer far less options CapSenseMBR3.
For my project the key points of CapSense MBR3 are:
- auto-tuning, so I don't have to do manual tuning from software each time I changed the material and thickness of the control panel faceplate.
- buttons and proximity loop have a number of features like sensor auto-reset, debounce and toggle built-in.
- buttons have LEDs with brightness control and an on board buzzer.
- can be set to work at 5V, I use in my design an Arduino working at 5V because of the other related components.
- can be reconfigured from Arduino or from EZ-Click graphic tool.
The most useful piece of information in setting the board and Cypress environment was "CY3280-MBR3 User Guide", but you can find on the product page links to documents and software required to better understand and operate MBR3 evaluation kit.
The kit came nicely packed and had added a RaspberryPi Model B as an external host.
Before use the kit some software have to be installed. I used for installation "CY3280-MBR3_Kit Setup" to be sure all required software is there. You can go with the ISO but I found that "CY3280-MBR3_Kit Setup" is enough. Installation was straightforward on Windows 7 Professional, no problems found.
I have began the testing part with tests described in chapter 3.4.1 - SmartSense Auto-tuning feature, chapter 4.3.7 Capacitance Variation Demonstration and chapter 5 of CY3280-MBR3 User Guide. I used initial settings described or loaded with the tests and also change some parameters to see how/if board reacts to changes of parameters.
For checking of auto-reset function with a metallic object, I placed a 10mm washer on top of a button. Button's LED turned on and after configured auto-reset period, LED turned off and touch button operate normally. With "Finger threshold" set to 50, finger proximity is detected at about 1 cm above the washer. I registered positive touches on buttons and proximity loop using different metallic and carbon rods/tubes.
I did not notice a change in sensitivity or detection range when supply voltage was changed between 1.8V, 3.3V and 5V.
I found EZ-Click 2.0 tool very easy to use to configure and monitor realtime touch buttons of CapSense MBR3 EVK.
For testing purposes and for the target project I used an 3mm acrylic overlay placed on top of existing overlay. I modified the following parameters and check how CapSenseMBR3 behaviour changes.
Sensitivity - can take values between 100 and 400. I noticed that lower values give greater detection range.
Finger threshold - lower values give greater detection range. I used for testing values from 128(default) to 50. With this values touch buttons responded steady every time with a 3mm acrylic overlay. Test were performed with automatic threshold disabled.
FSS - flanking sensor suppression - from EZ-Click -> CapSense sensor configuration -> FSS tab can be checked/unchecked for each button. When enabled, prevents triggering of adjacent buttons when a certain button is touched. Although, with FSS enabled, it is not possible to have multiple buttons triggered. In the end, I keep it disabled because I wanted to use combinations of buttons.
I tested proximity loop, connected to CS0/PS0(pin1) in two configurations:
- first, with proximity loop configured as simple touch button - from EZ-Click -> CapSense sensor configuration -> Number of proximity sensors - set to zero, finger threshold set to 50. In this configuration a steady detection occurred at a maximum distance of about 6cm.
- on second test, from EZ-Click -> CapSense sensor configuration -> Number of proximity sensors - set to 1. In this configuration a steady detection occurred at a maximum distance of about 8cm, but the detection process seemed a little slower. Opposed to simple touch button mode, in this mode more parameters can be configured.
I tested the kit powered from mini USB connector and 5V Arduino header. Over voltage, reverse voltage and externally regulated 1.8V were NOT tested.
EZ-Click also offer guidance for design your own touch sensors. From EZ-Click -> Configuration -> Open Design Toolbox -> an Excel document containing layout and sensor parameters is automatically opened.
Beside MS Office I test this feature with Open Office but I couldn't make it work. I'm not sure if this feature work with other spreadsheet editor because I don't find anything about it in the prerequisites.
Connecting CapSenseMBR3 kit to Arduino
I used for this test an Arduino Pro Micro board to read buttons status from CapSense MBR3 board and control WS2812 RGB LEDs I have in target project.
From EZ-Click -> Configuration -> Select target device, I set CapSenseMBR3 kit to run at 5V so I2C lines voltage match with 5V/16MHz Arduino Pro Micro board I/O lines voltage.
From design, MBR3 I2C lines are pulled to Vadj voltage (pag.49 from User Guide), Vadj is 5V in this case.
To allow MBR3 kit to communicate with Arduino board, jumpers J13 and J14 must be switched from position 1-2 to position 2-3(see User Guide).
I connected J3_9, J3_10, 5V and GND from MBR3 kit to A4, A5, 5V and GND from Arduino board.
As test code I used a modified version of "MBR3_Read_Status" sketch taken from here http://www.element14.com/community/thread/31800/l/cy3280-mbr3-example-with-arduino-unomega.
Everything worked from the first try, results were seen on Arduino serial monitor and from LEDs connected to Arduino.
You can find attached the code used for testing.
All in all, I found CapSense MBR3 EVK a stable and easy to use product with a good software support and documentation and a perfect match for my project. I'd like to thank Element14 and Cypress for the opportunity to evaluate this product and I hope to came back soon with a demo of the finished project.
Meantime, a short demo:
All the best