Increase the number of ATmega328P’s I/O ports with CAT9555
More I/Os, more fun!
Published Feb 14, 2024
Click board™
Expand 14 Click
Dev. board
Arduino UNO Rev3
Compiler
NECTO Studio
MCU
ATmega328P
Boost your microcontroller's capabilities with a versatile and trustworthy port expander
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Hardware Overview
How does it work?
Expand 14 Click is based on the CAT9555, a general-purpose I/O expander from ON Semiconductor. It contains two 8-bit configuration ports (input or output), input, output, and polarity inversion registers, alongside an I2C-compatible serial interface, where any of the sixteen I/Os can be configured as an input or output by writing to the configuration register. This port expander represents a simple solution when additional I/Os are needed while keeping interconnections to a minimum; particularly great for sensors, power switches, LEDs, pushbuttons, and fans. Each I/O port is 5V input tolerant, with a high current
I/O drive sink of up to 25mA and an I/O source of up to 10mA, maximum. Additionally, each I/O port is compatible with logic thresholds of 2.5V, 3.3V, and 5V. This Click board™ communicates with MCU using the standard I2C 2-Wire interface with a maximum clock frequency of 400kHz. The CAT9555 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 ADDR SEL to an appropriate position marked as 0 or 1.
Besides, it also features an active-low interrupt feature, routed to the INT pin of the mikroBUS™ socket, indicating to the host controller that an input state has been changed. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC 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.
Features overview
Development board
Arduino UNO is a versatile microcontroller board built around the ATmega328P chip. It offers extensive connectivity options for various projects, featuring 14 digital input/output pins, six of which are PWM-capable, along with six analog inputs. Its core components include a 16MHz ceramic resonator, a USB connection, a power jack, an
ICSP header, and a reset button, providing everything necessary to power and program the board. The Uno is ready to go, whether connected to a computer via USB or powered by an AC-to-DC adapter or battery. As the first USB Arduino board, it serves as the benchmark for the Arduino platform, with "Uno" symbolizing its status as the
first in a series. This name choice, meaning "one" in Italian, commemorates the launch of Arduino Software (IDE) 1.0. Initially introduced alongside version 1.0 of the Arduino Software (IDE), the Uno has since become the foundational model for subsequent Arduino releases, embodying the platform's evolution.
Microcontroller Overview
MCU Card / MCU
Architecture
AVR
MCU Memory (KB)
32
Silicon Vendor
Microchip
Pin count
28
RAM (Bytes)
2048
You complete me!
Accessories
Click Shield for Arduino UNO has two proprietary mikroBUS™ sockets, allowing all the Click board™ devices to be interfaced with the Arduino UNO board without effort. The Arduino Uno, a microcontroller board based on the ATmega328P, provides an affordable and flexible way for users to try out new concepts and build prototypes with the ATmega328P microcontroller from various combinations of performance, power consumption, and features. The Arduino Uno has 14 digital input/output pins (of which six can be used as PWM outputs), six analog inputs, a 16 MHz ceramic resonator (CSTCE16M0V53-R0), a USB connection, a power jack, an ICSP header, and reset button. Most of the ATmega328P microcontroller pins are brought to the IO pins on the left and right edge of the board, which are then connected to two existing mikroBUS™ sockets. This Click Shield also has several switches that perform functions such as selecting the logic levels of analog signals on mikroBUS™ sockets and selecting logic voltage levels of the mikroBUS™ sockets themselves. Besides, the user is offered the possibility of using any Click board™ with the help of existing bidirectional level-shifting voltage translators, regardless of whether the Click board™ operates at a 3.3V or 5V logic voltage level. Once you connect the Arduino UNO board with our Click Shield for Arduino UNO, you can access hundreds of Click boards™, working with 3.3V or 5V logic voltage levels.
Used MCU Pins
mikroBUS™ mapper
Take a closer look
Click board™ Schematic
Step by step
Project assembly
Start by selecting your development board and Click board™. Begin with the Arduino UNO Rev3 as your development board.
Track your results in real time
Application Output
1. Application Output - In Debug mode, the 'Application Output' window enables real-time data monitoring, offering direct insight into execution results. Ensure proper data display by configuring the environment correctly using the provided tutorial.
2. UART Terminal - Use the UART Terminal to monitor data transmission via a USB to UART converter, allowing direct communication between the Click board™ and your development system. Configure the baud rate and other serial settings according to your project's requirements to ensure proper functionality. For step-by-step setup instructions, refer to the provided tutorial.
3. Plot Output - The Plot feature offers a powerful way to visualize real-time sensor data, enabling trend analysis, debugging, and comparison of multiple data points. To set it up correctly, follow the provided tutorial, which includes a step-by-step example of using the Plot feature to display Click board™ readings. To use the Plot feature in your code, use the function: plot(*insert_graph_name*, variable_name);. This is a general format, and it is up to the user to replace 'insert_graph_name' with the actual graph name and 'variable_name' with the parameter to be displayed.
Software Support
Library Description
This library contains API for Expand 14 Click driver.
Key functions:
expand14_set_pin_directionThis function sets the direction of the selected pins.expand14_set_all_pins_valueThis function sets the value of all output pins.expand14_read_port_valueThis function reads the value of the selected port input pins.
Open Source
Code example
The complete application code and a ready-to-use project are available through the NECTO Studio Package Manager for direct installation in the NECTO Studio. The application code can also be found on the MIKROE GitHub account.
/*!
* @file main.c
* @brief Expand14 Click example
*
* # Description
* This example demonstrates the use of Expand 14 click board by setting and reading
* the ports state.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initializes the driver and performs the click default configuration which sets
* the port 0 as output and the port 1 as input.
*
* ## Application Task
* Sets the pins of the port 0 and then reads the status of both ports and
* displays the results on the USB UART approximately once per second.
*
* @author Stefan Filipovic
*
*/
#include "board.h"
#include "log.h"
#include "expand14.h"
static expand14_t expand14;
static log_t logger;
void application_init ( void )
{
log_cfg_t log_cfg; /**< Logger config object. */
expand14_cfg_t expand14_cfg; /**< Click config object. */
/**
* 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.
expand14_cfg_setup( &expand14_cfg );
EXPAND14_MAP_MIKROBUS( expand14_cfg, MIKROBUS_1 );
if ( I2C_MASTER_ERROR == expand14_init( &expand14, &expand14_cfg ) )
{
log_error( &logger, " Communication init." );
for ( ; ; );
}
if ( EXPAND14_ERROR == expand14_default_cfg ( &expand14 ) )
{
log_error( &logger, " Default configuration." );
for ( ; ; );
}
log_info( &logger, " Application Task " );
}
void application_task ( void )
{
uint8_t port_value = 0;
for ( uint16_t pin_num = EXPAND14_PIN_0_MASK; pin_num <= EXPAND14_PIN_7_MASK; pin_num <<= 1 )
{
expand14_set_all_pins_value( &expand14, pin_num );
expand14_read_port_value( &expand14, EXPAND14_PORT_0, &port_value );
log_printf( &logger, " Status port 0 (output): 0x%.2X\r\n", ( uint16_t ) port_value );
expand14_read_port_value( &expand14, EXPAND14_PORT_1, &port_value );
log_printf( &logger, " Status port 1 (input) : 0x%.2X\r\n\n", ( uint16_t ) port_value );
Delay_ms ( 1000 );
}
}
int main ( void )
{
/* Do not remove this line or clock might not be set correctly. */
#ifdef PREINIT_SUPPORTED
preinit();
#endif
application_init( );
for ( ; ; )
{
application_task( );
}
return 0;
}
// ------------------------------------------------------------------------ END
/*!
* @file main.c
* @brief Expand14 Click example
*
* # Description
* This example demonstrates the use of Expand 14 click board by setting and reading
* the ports state.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initializes the driver and performs the click default configuration which sets
* the port 0 as output and the port 1 as input.
*
* ## Application Task
* Sets the pins of the port 0 and then reads the status of both ports and
* displays the results on the USB UART approximately once per second.
*
* @author Stefan Filipovic
*
*/
#include "board.h"
#include "log.h"
#include "expand14.h"
static expand14_t expand14;
static log_t logger;
void application_init ( void )
{
log_cfg_t log_cfg; /**< Logger config object. */
expand14_cfg_t expand14_cfg; /**< Click config object. */
/**
* 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.
expand14_cfg_setup( &expand14_cfg );
EXPAND14_MAP_MIKROBUS( expand14_cfg, MIKROBUS_1 );
if ( I2C_MASTER_ERROR == expand14_init( &expand14, &expand14_cfg ) )
{
log_error( &logger, " Communication init." );
for ( ; ; );
}
if ( EXPAND14_ERROR == expand14_default_cfg ( &expand14 ) )
{
log_error( &logger, " Default configuration." );
for ( ; ; );
}
log_info( &logger, " Application Task " );
}
void application_task ( void )
{
uint8_t port_value = 0;
for ( uint16_t pin_num = EXPAND14_PIN_0_MASK; pin_num <= EXPAND14_PIN_7_MASK; pin_num <<= 1 )
{
expand14_set_all_pins_value( &expand14, pin_num );
expand14_read_port_value( &expand14, EXPAND14_PORT_0, &port_value );
log_printf( &logger, " Status port 0 (output): 0x%.2X\r\n", ( uint16_t ) port_value );
expand14_read_port_value( &expand14, EXPAND14_PORT_1, &port_value );
log_printf( &logger, " Status port 1 (input) : 0x%.2X\r\n\n", ( uint16_t ) port_value );
Delay_ms ( 1000 );
}
}
int main ( void )
{
/* Do not remove this line or clock might not be set correctly. */
#ifdef PREINIT_SUPPORTED
preinit();
#endif
application_init( );
for ( ; ; )
{
application_task( );
}
return 0;
}
// ------------------------------------------------------------------------ END
/*!
* @file main.c
* @brief Expand14 Click example
*
* # Description
* This example demonstrates the use of Expand 14 click board by setting and reading
* the ports state.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initializes the driver and performs the click default configuration which sets
* the port 0 as output and the port 1 as input.
*
* ## Application Task
* Sets the pins of the port 0 and then reads the status of both ports and
* displays the results on the USB UART approximately once per second.
*
* @author Stefan Filipovic
*
*/
#include "board.h"
#include "log.h"
#include "expand14.h"
static expand14_t expand14;
static log_t logger;
void application_init ( void )
{
log_cfg_t log_cfg; /**< Logger config object. */
expand14_cfg_t expand14_cfg; /**< Click config object. */
/**
* 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.
expand14_cfg_setup( &expand14_cfg );
EXPAND14_MAP_MIKROBUS( expand14_cfg, MIKROBUS_1 );
if ( I2C_MASTER_ERROR == expand14_init( &expand14, &expand14_cfg ) )
{
log_error( &logger, " Communication init." );
for ( ; ; );
}
if ( EXPAND14_ERROR == expand14_default_cfg ( &expand14 ) )
{
log_error( &logger, " Default configuration." );
for ( ; ; );
}
log_info( &logger, " Application Task " );
}
void application_task ( void )
{
uint8_t port_value = 0;
for ( uint16_t pin_num = EXPAND14_PIN_0_MASK; pin_num <= EXPAND14_PIN_7_MASK; pin_num <<= 1 )
{
expand14_set_all_pins_value( &expand14, pin_num );
expand14_read_port_value( &expand14, EXPAND14_PORT_0, &port_value );
log_printf( &logger, " Status port 0 (output): 0x%.2X\r\n", ( uint16_t ) port_value );
expand14_read_port_value( &expand14, EXPAND14_PORT_1, &port_value );
log_printf( &logger, " Status port 1 (input) : 0x%.2X\r\n\n", ( uint16_t ) port_value );
Delay_ms ( 1000 );
}
}
int main ( void )
{
/* Do not remove this line or clock might not be set correctly. */
#ifdef PREINIT_SUPPORTED
preinit();
#endif
application_init( );
for ( ; ; )
{
application_task( );
}
return 0;
}
// ------------------------------------------------------------------------ END
Additional Support
Resources
Category:Port expander
