EXPAND 5 Click features a low-voltage 24-bit I2C and SMBus I/O expander. This 24-bit I/O expander is designed to provide general-purpose remote I/O expansion for most microcontroller families via the I2C serial interface. This Click board™ features the TCA6424A from Texas Instruments, and it operates over a power supply voltage range of 1.65V to 5.5V. Wide voltage range allows the TCA6424A to interface with next-generation microprocessors and microcontrollers on the SDA/SCL side, where supply levels are dropping down to conserve power. The P-port outputs have high-current sink capabilities for directly driving LEDs while consuming low device current.

EXPAND 5 Click is supported by a mikroSDK compliant library, which includes functions that simplify software development.

EXPAND 5 Click uses the TCA6424A IC, low-voltage 24-bit I2C, and SMBus I/O expander from Texas Instruments. This 24-bit I/O expander for the two-line bidirectional bus is designed to provide general-purpose remote I/O expansion for most microcontroller families via the 400-kHz fast I2C bus. This Click board™ features on-board I2C address jumpers, pull-up resistors, power supply bypass capacitor, and power LED. It operates over a flexible power supply voltage range of 1.65V to 5.5V, which makes it suitable for 3.3V and 5V microcontrollers.

At power-on, the I/O pins are configured as inputs. However, the microcontroller can enable the I/Os as either inputs or outputs by writing to the I/O configuration bits. The data for each input or output is kept in the corresponding input or output register. The polarity of the Input Port register can be inverted with the Polarity Inversion register. The microcontroller can reset the TCA6424A in the event of a timeout or other improper operation by asserting a low in the RESET input. The power-on reset puts the registers in their default state and initializes the I2C interface. The RESET pin causes the same reset/initialization to occur without depowering the part. This Click board™ also has an open-drain interrupt (INT) output that is activated when any input state differs from its corresponding Input Port register state and is used to indicate to the microcontroller that an input state has changed. By sending an interrupt signal on this line, the remote I/O can inform the microcontroller if there is incoming data on its ports without having to communicate via the I2C bus. Thus, the TCA6424A can remain a simple peripheral device.

The TCA6424A communicates with MCU using the standard I2C 2-wire interface. The TCA6424A can respond to one of two 7-bit I2C Bus peripheral addresses. The first 6 bits (MSBs) have been factory programmed to 010001. The address pin, ADDR (Pin 26) is programmed by the user and determines the LSB of the peripheral address and it can be selected by onboard SMD jumper labeled as ADDR SEL allowing selection of the peripheral address LSB. The last bit of the peripheral address defines the operation (read or write) to be performed. A high (1) selects a read operation, while a low (0) selects a write operation.

This Click board™ can be supplied and interfaced with both 3.3V and 5V without the need for any external components. The onboard SMD jumper labeled as VCC SEL allows voltage selection for interfacing with both 3.3V and 5V microcontrollers. More information about the TCA6424A can be found in the attached datasheet. However, this Click board™ comes equipped with a library that contains easy to use functions and a usage example that may be used as a reference for the development.

• Interface: GPIO, I²C
• Compatibility: mikroBUS™
• Dimensions: 57.15 x 25.4mm
• Input Voltage: 3.3V or 5V
• Supply Voltage: Min. -0.5V, Max. 6.5V
• Maximum Output Current: 25mA
• Maximum Frequency: 400 kHz
• Operating Temperature Range: Min. -40°C, Max. +85°C

• Schematic
• TCA6424A Datasheet
• mikroSDK
• GitHub