Create solutions with innovative touch-sensitive controls using CAP1166 and ATmega644
Tap into endless possibilities
Published Aug 07, 2023
Click board™
Cap Touch 2 click
Dev Board
EasyAVR v7
Compiler
NECTO Studio
MCU
ATmega644
Dive into the world of capacitive touch sensing and transform your ideas into touch-sensitive reality
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Hardware Overview
How does it work?
Cap Touch 2 Click is based on the CAP1166, a 6-channel capacitive touch sensor with 6 LED drivers from Microchip. This IC comprises six input capacitive touch channels, implemented with the RightTouch® technology, six LED drives with programmable signaling functions, and the logic section, which uses the standard SPI communication interface. Besides the SPI bus, the logic section uses a few more lines - for the device reset and triggering the alert (interrupt) event. The board has six PCB pads to sense touch or proximity events. These pads are the only elements on the top of the board, allowing the protective acrylic glass layer to be installed. These pads can be programmed to generate a touch event for both when they are pressed and when they are released. The capacitive sensor channels feature programmable sensitivity and an automatic recalibration, used to compensate for environmental changes. The recalibration procedure can be triggered either automatically or on-demand, and it is used to set the base register value for the “not touched” state of the input channel. The enabled input channels are polled in a cyclic order. A touch event will be generated if
the difference between the base value and the measured value on a particular channel is over the threshold. The CAP1166 IC also integrates sections that provide efficient interference protection. The EMI and RFI detection sections protect by discarding the corrupted bytes if the detected noise threshold is exceeded. Also, false input readings, such as the negative values and “stuck button” events, are handled by the internal algorithms, which will set the respective bits to indicate the problem, and can be set to trigger a recalibration procedure. Multiple touch pattern detection (MTPD) sets the pattern to generate a touch event. This pattern may consist of multiple specific sensors touched at once, a minimal number of touched sensors, or when their noise flag bit is set in the status register. This function can be used to detect a closed lid or similar event. Cap Touch 2 click contains six LEDs mounted on the back side of the PCB inside the specially designed openings. These LEDs can be linked to the corresponding sensing channel or controlled by the host MCU. As described above, these LEDs can be programmed to indicate a touch event with a range of lighting effects, including
breathing, two modes of pulsing with programmable parameters, and an ON-OFF state. The interrupt engine allows one to differentiate between simple touch and touch-and-hold events. The interrupt can be generated once when a pad touch is detected or repeatedly generated while the pad is touched. The programmable timer is started after the first touch event on a specific channel. The interrupt is generated in the programmed intervals if no release event is detected after the timer expires. This function is very useful for building volume up/down buttons, light-dimming buttons, and similar applications. The interrupt event will also drive the /ALERT pin to a state defined in the configuration register. This pin is routed to the mikroBUS™ INT pin and is used to trigger an interrupt event on the host MCU. The RST pin is routed to the RST pin of the mikroBUS™ and is used to reset the CAP1166 IC. This pin must be set to a HIGH logic level to reset the device. This will clear all the readings and reset the configuration registers to their factory default values. The device will be kept in a Deep Sleep mode until this pin is set to a LOW logic level. This pin is equipped with a pull-down resistor.
Features overview
Development board
EasyAVR v7 is the seventh generation of AVR development boards specially designed for the needs of rapid development of embedded applications. It supports a wide range of 16-bit AVR microcontrollers from Microchip and has a broad set of unique functions, such as a powerful onboard mikroProg programmer and In-Circuit debugger over USB. The development board is well organized and designed so that the end-user has all the necessary elements in one place, such as switches, buttons, indicators, connectors, and others. With four different connectors for each port, EasyAVR v7 allows you to connect accessory boards, sensors, and custom electronics more
efficiently than ever. Each part of the EasyAVR v7 development board contains the components necessary for the most efficient operation of the same board. An integrated mikroProg, a fast USB 2.0 programmer with mikroICD hardware In-Circuit Debugger, offers many valuable programming/debugging options and seamless integration with the Mikroe software environment. Besides it also includes a clean and regulated power supply block for the development board. It can use a wide range of external power sources, including an external 12V power supply, 7-12V AC or 9-15V DC via DC connector/screw terminals, and a power source via the USB Type-B (USB-B)
connector. Communication options such as USB-UART and RS-232 are also included, alongside the well-established mikroBUS™ standard, three display options (7-segment, graphical, and character-based LCD), and several different DIP sockets which cover a wide range of 16-bit AVR MCUs. EasyAVR v7 is an integral part of the Mikroe ecosystem for rapid development. Natively supported by Mikroe software tools, it covers many aspects of prototyping and development thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.
Microcontroller Overview
MCU Card / MCU
Architecture
AVR
MCU Memory (KB)
64
Silicon Vendor
Microchip
Pin count
40
RAM (Bytes)
4096
Used MCU Pins
mikroBUS™ mapper
Take a closer look
Schematic
Step by step
Project assembly
Start by selecting your development board and Click board™. Begin with the EasyAVR v7 as your development board.
Track your results in real time
Application Output via UART Mode
1. Once the code example is loaded, pressing the "FLASH" button initiates the build process, and programs it on the created setup.
2. After the programming is completed, click on the Tools icon in the upper-right panel, and select the UART Terminal.
3. After opening the UART Terminal tab, first check the baud rate setting in the Options menu (default is 115200). If this parameter is correct, activate the terminal by clicking the "CONNECT" button.
4. Now terminal status changes from Disconnected to Connected in green, and the data is displayed in the Received data field.
Software Support
Library Description
This library contains API for Cap Touch 2 Click driver.
Key functions:
captouch2_detect_touch- Touch Detect functioncaptouch2_check_interrupt- Interrupt Check functioncaptouch2_reset- Reset function
Open Source
Code example
This example can be found in NECTO Studio. Feel free to download the code, or you can copy the code below.
/*!
* \file
* \brief CapTouch2 Click example
*
* # Description
* The demo application shows the button reading and checking.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Configuring clicks and log objects.
* Reset device and settings the click in the default configuration.
*
* ## Application Task
* Calls function to check touch detection (is interrupt occured) and shows message on
* USB UART on which input touch is detected or on which input touch is released.
* Also turns on LED on which linked input interrupt occured.
*
* \author Katarina Perendic
*
*/
// ------------------------------------------------------------------- INCLUDES
#include "board.h"
#include "log.h"
#include "captouch2.h"
// ------------------------------------------------------------------ VARIABLES
static captouch2_t captouch2;
static log_t logger;
// ------------------------------------------------------ APPLICATION FUNCTIONS
void application_init ( void )
{
log_cfg_t log_cfg;
captouch2_cfg_t cfg;
/**
* Logger initialization.
* Default baud rate: 115200
* Default log level: LOG_LEVEL_DEBUG
* @note If USB_UART_RX and USB_UART_TX
* are defined as HAL_PIN_NC, you will
* need to define them manually for log to work.
* See @b LOG_MAP_USB_UART macro definition for detailed explanation.
*/
LOG_MAP_USB_UART( log_cfg );
log_init( &logger, &log_cfg );
log_info( &logger, "---- Application Init ----" );
// Click initialization.
captouch2_cfg_setup( &cfg );
CAPTOUCH2_MAP_MIKROBUS( cfg, MIKROBUS_1 );
captouch2_init( &captouch2, &cfg );
captouch2_reset( &captouch2 );
Delay_ms( 200 );
captouch2_default_cfg( &captouch2 );
Delay_ms( 100 );
log_info( &logger, ">> Cap Touch 2 is initialized " );
}
void application_task ( void )
{
uint8_t cnt;
uint8_t sensor_results[ 6 ];
captouch2_detect_touch( &captouch2, &sensor_results[ 0 ] );
for ( cnt = 0; cnt < 6; cnt++ )
{
if ( sensor_results[ cnt ] == 1 )
{
log_printf( &logger, "Input %d is touchedr\r\n", cnt + 1 );
}
else if ( sensor_results[ cnt ] == 2 )
{
log_printf( &logger, "Input %d is released\r\n", cnt + 1 );
}
}
}
void main ( void )
{
application_init( );
for ( ; ; )
{
application_task( );
}
}
// ------------------------------------------------------------------------ END
