Touchpad 5 Click

How does it work?

Touchpad 5 Click as its foundation uses the IQS550, a projected capacitive touch and proximity trackpad/touchscreen controller from Azoteq. The IQS550 offers high sensitivity proximity wake-up and contact detection (touch) through many I2C-controllable sensor lines. Its advanced on-chip signal processing capabilities provide stable high performance with high sensitivity. Also, multiple filters are implemented to detect and suppress noise, track slow varying environmental conditions, and avoid the effects of possible drift. The IQS550 controller is very flexible, providing numerous outputs such as proximity, touch, snap, touch strength, area, and actual finger position, all in one solution.

On Click boards™ front side, a clearly defined field represents a touchpad area. This area is a matrix of conductive electrodes on the PCB, electrically isolated from each other, arranged as rows and columns of X and Y in a dimension of 29x23mm. An electrode consists of multiple diamond-shaped elements connected to the next with a conductive neck.

The controller uses the principle of projected capacitance charge transfer on the trackpad. When a conductive object such as a human finger approaches the sense pad, it will decrease the detected capacitance. Thresholds are applied to the sensor data to identify proximity and touch deviation areas. The contours of the touch areas are then translated to Cartesian position coordinates that are continuously monitored to recognize gestures. A user has access to all of the data layers – the raw sensor data, the sensor proximity/touch status data, the XY coordinates, and the gesture outputs.

Touchpad 5 Click communicates with MCU using the standard I2C 2-Wire interface with a maximum clock frequency of 400kHz, fully adjustable through software registers. An additional ready signal, routed on the INT pin of the mikroBUS™ socket, is added, which indicates when the communication window is available with new data for optimal response. Thus, it is optimal for the response rate to use the INT pin as a communication trigger. Alongside this pin, this Click board™ has a Reset feature routed to the RST pin on the mikroBUS™ socket, which with a low logic level, puts the module into a Reset state, and with a high level, operates the module normally.

This Click board™ can be operated only with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. However, the Click board™ comes equipped with a library containing functions and an example code that can be used, as a reference, for further development.

Specifications

Pinout diagram

This table shows how the pinout on Touchpad 5 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
Reset	RST	2	RST	INT	15	INT	Interrupt
	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	Ground

Onboard settings and indicators

Touchpad 5 Click electrical specifications

Software Support

We provide a library for the Touchpad 5 Click as well as a demo application (example), developed using MikroElektronika compilers. The demo can run on all the main MikroElektronika development boards.

Package can be downloaded/installed directly from NECTO Studio Package Manager(recommended way), downloaded from our LibStock™ or found on Mikroe github account.

Library Description

This library contains API for Touchpad 5 Click driver.

Key functions

• touchpad5_get_touch This function get touch XY data.

• touchpad5_get_status This function get status proximity, touch or snap data.

• touchpad5_wait_ready This function waits for the communication window to be available.

Example Description

This example demonstrates the use of Touchpad 5 Click board™ by utilizing the touchpad XY and snap functionalities.

void application_task ( void )  
 { 
     // Busy wait for communication window availability 
     touchpad5_wait_ready( &touchpad5 ); 
     // Get touchpad XY data 
     touchpad5_get_touch( &touchpad5, &touch_data ); 

     // Detecting the snap (click) criteria 
     if ( touchpad5_detect_snap( &touchpad5, snap_buffer, SNAP_BUFFER_SIZE, &snap_reference) && touch_data.touch_strength > 0 ) 
     { 
         log_printf( &logger, "----------------------------------------------------------------rn" ); 
         log_printf( &logger, "rn* Snap (click) event occured with strength: %u *rn",  
                                                                         ( uint16_t ) touch_data.touch_strength );  
         log_printf( &logger, "----------------------------------------------------------------rn" ); 
         Delay_ms( 100 ); 
     } 
     // Detecting the touch criteria 
     else if ( touch_data.x_pos > 0 && touch_data.y_pos > 0 && touch_data.touch_strength > TOUCH_STRENGTH_THRESHOLD ) 
     { 

         log_printf( &logger, "----------------------------------------------------------------rn" ); 
         log_printf( &logger, " rnTouch with Tag ID %u detectedrn",  ( uint16_t ) touch_data.id_tag ); 
         log_printf( &logger, "Coordinate X = %u rn",                               touch_data.x_pos ); 
         log_printf( &logger, "Coordinate Y = %u rn",                               touch_data.y_pos ); 
         log_printf( &logger, "Touch strength = %u  rn",               ( uint16_t ) touch_data.touch_strength ); 
         log_printf( &logger, "----------------------------------------------------------------rnrn" ); 
         Delay_ms( 100 ); 
     } 

     // Monitoring to determine whether the reset occurred on the device after the last ack reset      
     if ( touch_data.xy_info & TOUCHPAD5_SHOW_RESET ) 
     { 
         log_printf( &logger, "----------------------------------------------------------------rn" ); 
         log_error( &logger, "rn Unexpected reset occured. rn" );  
         log_printf( &logger, "----------------------------------------------------------------rnrn" ); 
     } 

     Delay_ms( 50 );        
 }

The full application code, and ready to use projects can be installed directly from NECTO Studio Package Manager(recommended way), downloaded from our LibStock™ or found on Mikroe github account.

Other Mikroe Libraries used in the example:

• MikroSDK.Board
• MikroSDK.Log
• Click.TouchPad5

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. UART terminal is available in all MikroElektronika compilers.

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.