As mentioned in my previous post CapSense Evaluation Kit - First Impressions, I planned to run through the user guide to familiarise myself with the board. I was particularly interested in understanding the configuration of the switch sensitivity and the SmartSense auto-tuning feature. I'd effectively run through parts 1 and 2 already so I returned at section 3 Kit Operation. I ran through the setup instructions 3.1 - 3.3 with no issues.
It's worth mentioning the kit features:
- Four CapSense buttons of two different sizes – two buttons of 10-mm diameter (BTN1 and BTN2) and two buttons of 11-mm diameter (BTN3 and BTN4)
- LEDs corresponding to sensors indicating button touch
- A buzzer
- Shield electrode pin for water tolerance
- I2C selection jumpers
- Arduino-compatible headers
- One proximity loop and a corresponding LED to indicate proximity state (on/off)
- A host interrupt pin
- Two slide switches on two CapSense buttons to vary trace capacitance and demonstrate
Note: The CS15 pin of the MBR3 device is multiplexed for the CapSense button, host interrupt, and shield electrode. Similarly, GPO7 is multiplexed for general-purpose output, host interrupt, and buzzer output. All three features – host interrupt, buzzer, and shield electrode (water tolerance) cannot be enabled simultaneously.
For my evaluation the key things here are the button sizes, I need to be consistent in my testing so will likely go for the larger 11mm BTN3 at the top of the board.
I ran through the auto-tuning section in 3.4.1 but then repeated the tests with the automatic threshold off but the sensors seemed to cope with that too so I'm not sure how these two features relate to each other.
Section 4 mostly is a reading exercise but there are a couple of tests.
4.3.3.1. Tests with an "external power supply"
I did not quite understand the requirement for this so have not completed this test.. "To operate the kit in externally regulated mode at 1.8 V, solder resistors R84 and R85 with 0-ohm resistors" if all that is needed is a jumper then why not just fit it with a header and provide a couple of jumpers in the kit?
4.3.3.3 Power consumption
For this test I created a simple adapter.
Whilst idle the current was fluctuating between 0.04mA and 0.2mA. When a switch was touched and the LED was lit the current was in the order of 0.4mA. During upload this increased to 3mA. When I activated the proximity switch current increased to 1.1mA.
Section 5 looks at loading up the sample projects.
The LED test performed fine. For the proximity test, I found the loop started detecting at about 10cm, it also reported signal to noise errors for longer than mentioned in the manual but it did eventually settle down. The water test is a little un-nerving but performed fine.
Section 5.3. Has examples for a PSoC 4 Pioneer Kit, there are equivalent Example with Arduino (Uno/Mega) but I need read these carefully as they require a slight modification to the board.
Section 6 tests did not seem relevant as these look at the PSoC 5LP rather than the MBR3 but they could be useful if the I2C address gets mixed up.
I still feel that I need to learn a bit more about the sensitivity and threshold settings to do a proper glove / panel material test but for my quick experiments the switches behave normally with gloves.
So next is to configure the board for testing the gloves and test different scenarios.
