EXPAND Click

How does it work?

Expand Click is based on the MCP23S17, a 16-bit general-purpose parallel I/O expansion with the serial interface from Microchip. The MCP23S17 consists of multiple 8-bit configuration registers for input, output, and polarity selection. The host MCU can enable the I/Os as either inputs or outputs by writing the I/O configuration bits with data for each input or output kept in the corresponding input or output register. This port expander represents a simple solution when additional I/Os are needed while keeping interconnections to a minimum. It features two double-row unpopulated headers for connecting I/O devices.

This Click board™ communicates with MCU using the standard 4-Wire SPI serial interface with a maximum 10MHz frequency. The MCP23S17 has a 7-bit slave address with the first four MSBs fixed to 0100. The address pins A0, A1, and A2 are programmed by the user and determine the value of the last three LSBs of the slave address, which can be selected by positioning onboard SMD jumpers labeled as HARDWARE ADDRESS SEL to an appropriate position marked as 1 or 0. This way, the MCP23S17 provides the opportunity of using more Extend Clicks on a single host MCU.

Besides, it also has an interrupt feature, routed to the INT pin of the mikroBUS™ socket, indicating to the host controller that an input state has been changed alongside the general reset feature. Two interrupt pins on the MCP23S17 can be associated with their respective ports or logically OR’ed together so that both pins will activate if either port causes an interrupt. The desired interrupt port can be selected by positioning an onboard SMD jumper labeled J4 in an appropriate position.

This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the PWR SEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. However, the Click board™ comes equipped with a library containing easy-to-use 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 EXPAND 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
SPI Chip Select	CS	3	CS	RX	14	NC
SPI Clock	SCK	4	SCK	TX	13	NC
SPI Data OUT	SDO	5	MISO	SCL	12	NC
SPI Data IN	SDI	6	MOSI	SDA	11	NC
Power Supply	3.3V	7	3.3V	5V	10	5V	Power Supply
Ground	GND	8	GND	GND	9	GND	Ground

Onboard settings and indicators

EXPAND Click electrical specifications

Software Support

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

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

Library Description

This library contains API for Expand Click driver.

Key functions

• Set expander PORTA direction function.

• Write one byte of data to register for PORTA function.

• Reset function.

Example Description

This applicatioin use for expansion I/O lines.

 void application_task ( void ) 
 { 
     pin_position = 1; 

     for ( position = 0; position < 8; position++ ) 
     { 
         expand_write_port_a( &expand, EXPAND_SPI_MODULE_POSITION_0, pin_position ); 
         log_printf( &logger, " PA%d setrn", (uint16_t) position ); 

         port_status = expand_read_port_b( &expand, EXPAND_SPI_MODULE_POSITION_0 ); 

         log_printf( &logger, " Status PB (input) : %d  rn", (uint16_t) port_status ); 
         log_printf( &logger, "----------------rn" ); 

         pin_position <<= 1; 

         Delay_ms( 500 ); 
     } 
 }

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

Other Mikroe Libraries used in the example:

• MikroSDK.Board
• MikroSDK.Log
• Click.Expand

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 MIKROE compilers.

mikroSDK

This Click board™ is supported with mikroSDK – MIKROE 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.