I/O Expander shield is a shield used to expand the number of I/Os of an Arduino Uno. It is based on the chipset MCP23017. The chipset MCP23017 communicates with Arduino Uno through I2C interface. It adds GPIOA and GPIOB, a total of 16 I/Os. There are two LEDs and two buttons on the shield. User can decide if they want to use the built-in LED/buttons or not by using the 4-bit DIP switch.
- 16 bidirectional I/O ports. Default is input state.
- High-speed IIC interface (MCP23017): 100kHz, 400kHz, 1.7MHz
- Three hardware address pins allow up to eight devices on the bus
- Configurable interrupt output pin: can be configured for active-high (output), active-low (output) or open-drain (output)
- INTA and INTB can be configured to work independently or jointly
- Configurable interrupt sources: the interrupt changes according to the configured register defaults or pin level changes
- External reset input
- Low standby current: 1μA (max)
- Operating voltage:
- 1.8V to 5.5V (-40 ° C to +85 ° C)
- 2.7V to 5.5V (-40 ° C to +85 ° C)
- 4.5V to 5.5V (-40 ° C to +125 ° C)