CAP WHEEL CLICK
PID: MIKROE-3203
Weight: 25 g
CAP Wheel Click is a capacitive touch sensor with round shaped electrodes integrated
on a Click board™. This click can sense touch even through plastic, wood, or other
dielectric materials, which can be used to protect the surface of the PCB and the sensor
pad trace itself. Therefore, this Click board™ comes with overlay, made of plexiglass.
Unlike the mechanical button, the capacitive touch button lasts much longer, it is not
prone to damage and wear over time and it is very reliable.
Cap Wheel click is supported by a mikroSDK compliant library, which includes functions
that simplify software development. This Click board™ comes as a fully tested product,
ready to be used on a system equipped with the mikroBUS™ socket
Capacitive sensors are a very popular method of controling various devices. Besides
the aforementioned benefits, having a touch sensitive button on a device allows for a
compact design, opens possibilities for various kinds of human-machine interface and it looks good and modern, especially if 8 LEDs array that CAP Wheel click has onboard
is taken into account. CAP Wheel click can find its place among many applications - for
touch activated lighting controls, process control, touch activated control panels, toys
and any other applications that need a switch or an encoder.
HOW DOES IT WORK?
Although it looks simple at first glance, capacitive touch sensing is not an easy task.
There are many parameters that need to be sampled, filtered, compared and processed
before positive touch detection and its position are confirmed. To make this possible,
Cap Touch click utilizes the IQS333, ProxSense® IC, a 9-channel projected (or 7channel self) capacitive proximity and touch controller from Azoteq. This IC has some
advanced features such as the auto drift compensation, Long proximity range,
Automatic adjustment for optimal performance (ATI), two Configurable 11-bit
sliders/scroll wheels and more. These features enable CAP Wheel click exhibit very
reliable and accurate touch detection.
Capacitive touch sensing is based on detecting a change in capacitance, due to the
influence of a foreign object. Basically, the capacitance of the sensor, also known as the
antenna, is measured and monitored and if a significant change occurs, after
processing by the detection integrator, a touch event is acknowledged. To maximize
performance, many routing requirements need to be met in the sensing electrodes
design. The relation between the sensing elements in position and size is crucial. CAP
Wheel click is designed with these requirements in mind and electrodes are „SelfCapacitive Wheel“ shaped.
CAP Wheel click also contains 8 LEDs whose function can be user-defined. LEDs are
connected to PWM LED driver pins on IQS333 which means that the user can turn
LEDs on or off and control illumination, using the dimming modes that IQS333 supports.
The IQS333 IC interfaces to a master controller via a 3-wire (SDA, SCL, and RDY)
serial interface bus that is I2C™ compatible, with a maximum communication speed of
400kbit/s. The host MCU has the capability to force a communication at any time, by
pulling the RDY line low. The communication will start directly following the current
conversion cycle. If the event is terminated by the watchdog timer, the device will reset.
After every power on cycle, the device will recalibrate itself. It will take some time, so it
should be taken into consideration when building custom applications. MikroElektronika
provides libraries and the demo application, that can be used as a reference for any
future designs.
As mentioned before, this Click board™ is I2C™ compatible and uses SCL, SDA and
RDY pins for communication which are routed to SCL, SDA and INT pin on mikroBUS™
respectively. Besides that, CLR pin is available on board which is routed to RST pin on
mikroBUS™ and used to master reset the IC.
SPECIFICATIONS
Type
Capacitive
Applications
It can be used for touch activated lighting controls, process control, touch
activated control panels, toys and any other applications that need a
switch or an encoder.
On-board
modules
IQS333, ProxSense® IC, a 9-channel projected (or 7-channel self)
capacitive proximity and touch controller from Azoteq.
Key Features
Auto drift compensation, Long proximity range, Automatic adjustment for
optimal performance (ATI), 2 Configurable 11-bit sliders/scroll wheels and
more.
Interface
GPIO,I2C
Input Voltage
3.3V
Click board
size
L (57.15 x 25.4 mm)
PINOUT DIAGRAM
This table shows how the pinout on Cap Touch click corresponds to the pinout on the
mikroBUS™ socket (the latter shown in the two middle columns).
Notes
Pin
Pin
Notes
NC
1
AN
PWM
16
NC
CLR
2
RST
INT
15
RDY
NC
3
CS
RX
14
NC
NC
4
SCK
TX
13
NC
NC
5
MISO
SCL
12
SCL
I2c Clock
NC
6
MOSI
SDA
11
SDA
I2C Data
Power Supply
+3.3V
7
3.3V
5V
10
NC
Ground
GND
8
GND
GND
9
GND
Master Clear
Ready Output
Ground
ONBOARD SETTINGS AND INDICATORS
Label
Name
Default
Description
LD1-LD8
-
-
User configurable LED indicator
LD9
PWR
-
Power LED Indicator
SOFTWARE SUPPORT
We provide a library for the CAP Wheel Click on our LibStock page, as well as a demo
application (example), developed using MikroElektronika compilers. The demo can run
on all the main MikroElektronika development boards.
Library Description
Library performs the control of the CAP Wheel Click board and allows to set all
necessary configurations which include number of activated channels, threshold values
for touch for each channel and for proximity, and etc. Also can read data from
capacitance wheel and represent that value on LEDs. For more details check
documentation.
Key functions:
uint8_t capwheel_writeReg( uint8_t register_address, uint8_t *dataIn, uint8_t nBytes ) -
Function writes the determined number of bytes to the register.
void capwheel_getData( uint16_t *wheelData ) - Function reads data from wheel 1 and stores this
value in memory via output parameter.
void capwheel_setOutput( uint16_t inputData, uint8_t outputMode ) - Function sets output
LEDs depending on the input wheel data value in the way which is determined with the ouputMode
parameter.
Examples description
The application is composed of three sections :
System Initialization - Initializes peripherals and pins.
Application Initialization - Initializes I2C interface, performs the device reset and activates the
desired channels (from CH0 to CH9), in this example all channels are activated.
Application Task - (code snippet) - Checks is sense data ready for reading and if was ready, then
reads wheel coordinates and sends these results to the LEDs.
void applicationTask()
{
readyCheck = capwheel_checkDataReady();
if (readyCheck == _CAPWHEEL_DATA_READY)
{
capwheel_getData( &senseData );
capwheel_setOutput( senseData, _CAPWHEEL_LED_BRIGHTNESS_NUMBER );
}
}
The full application code, and ready to use projects can be found on our LibStock page.
Other mikroE Libraries used in the example:
I2C
Additional notes and informations
Depending on the development board you are using, you may need USB UART
click, USB UART 2 click or RS232 click to connect to your PC, for development systems
with no UART to USB interface available on the board. The terminal available in all
MikroElektronika compilers, or any other terminal application of your choice, can be
used to read the message.
MIKROSDK
This Click board is supported with mikroSDK - MikroElektronika Software Development
Kit. To ensure proper operation of mikroSDK compliant Click board demo applications,
mikroSDK should be downloaded from the LibStock and installed for the compiler you
are using.
For more information about mikroSDK, visit the official page.
.
https://www.mikroe.com/cap‐wheel‐click/6‐28‐19
