I volunteered for this road test because I thought that capacitive switches could be a good solution for front panels for CNC or measuring equipment in a workshop environment. I particularly liked the idea that you could design your switches on a PCB and then connect to a microcontroller via I2C with things like debouncing and calibration handled by the MBR3 chip. Alternativelty the GPO pins can be configured using to provide signals directly. This also means less wiring and no mechanical parts to break or get dirty so cost and reliability (as well as reduced build time) should also be better. The CapSense solution also has low power options (the evaluation kit has test points to measure current) so could be good for battery operated equipment.
For my roadtest report I'm going to look at how the switches perform under different situations particularly gloved operation and with different thicknesses of front panel and also compare this solution to the alternatives. For this blog I'm just going to look at getting started with the kit.
In side the kit is a USB cable, a dropper (for the water tests), the CapSense board and a plastic overlay. As expected the software for the kit is a download rather than being provided in the box. The QR code on the front of the board links to a page for the CY3280-MBR3 CapSense
MBR3 Evaluation Kit with the documentation and software downloads. If you do want to burn a CD then an ISO image is provided. The userguide and quickstart guide are provided in English and Chinese.
The board seems quite complex but the core parts are the CY8CMBR3116CY8CMBR3116 chip and a few discrete components, the additional chip and circuitry is for a USB to I2C bridge. The board is packed with testing features such as jumpers and switches to enable and disable tests and headers to connect to an ardiuno or similar.
The quickstart guide has 5 steps firstly to download the "latest kit software" it was not totally obvious which to download but as I'd watched the Designing Capacitive User Interfaces for Single Board Computers webinar, I knew I needed one with EZ-Click in it so chose the CY3280-MBR3 Kit Setup (Kit Files + EZ-Click + PSoC Programmer) download. There are some other interesting downloads, for instance the "Hardware files" have both the Gerber files needed to create your own PCB and also the full schematics of the board. You might want to download the user guide but that is also included in this main setup.
I'm using Windows 7 Home Premium (32bit)
The software setup seems initially very straightforward, the only option is the location of the files. However that launches a second installer with some options. So I referred to the User Guide, this does have the details of which download you need (I had picked correctly) and walks you through the software install.
At the end of the install and update manger appeared so I ran through that upgrade too, this does seem to re-download and replace most of the components just installed.
I skipped the water for the time being and plugged in the board. The 4 buttons worked nicely lighting up when a finger got close.
I started a new project and selected the CY8CMBR3116, had a quick play and managed to enable the proximity sensor but disabled buttons 2 to 4. The loading of configuration to the board is very quick, looking at the .h file that is generated the reason for this is clear in that only 128bytes of data need sending. This would mean that you could happily program this board from a microcontroller.
I tried to load the LED toggle project provided with the kit at "C:\Program Files\Cypress\CY3280-MBR3 EVK\1.0\Firmware\Config Files". The software refused to load this as it wanted to create a lock file. I re-ran EZ-Click as administrator and the file loaded correctly, reading the manual later this is covered. The LED toggle did demonstrate that the buzzer works fine, I also realised at this point that the pins were labelled on the front of the board so you'd know which 4 are used for the switches and LEDs. The proximity detection project is good to show the range of the proximity sensor, using the CapSense output tab.
I loaded the water tolerance project to return the board back to it's default.
The install seems quite large for what it is doing but the software seems to work well and is easy to use. The EZ-Click configuration is good in that it reports of errors before you try to upload and stops you doing so if you've chosen incompatible options. The documentation is very clear and comprehensive. I've read the design guide on the website and also noted that there is a menu option in EX-Click that brings up a spreadsheet with the design guide details.
I am new to capacitive switches and to this board so there's a bit of learning to be done but the user guide is detailed so I plan to follow the testing mentioned in there. There are a few references to external components so I may not be able to complete all of the tests.