Product description
Electrokit EKM017 - 8-Channel I²C I/O Expander With Level Shifter (TCA6408A)
The EKM017 is an I/O expander with eight GPIO channels, based on the TCA6408A from Texas Instruments. The module communicates over the I²C bus and provides both input and output functionality with individual configuration per port.
Each channel can be set as either an input or output, offering flexibility for various control and monitoring applications. Thanks to separate power supplies for the I²C side (VCCi) and the port side (VCCp), integrated level shifting is supported between different logic levels (1.65-5.5 V) without the need for external level translators.
The TCA6408A is particularly well-suited for systems where the main microcontroller has a limited number of GPIOs. Each port can drive LEDs directly with up to 10 mA (source) or 25 mA (sink). An interrupt output (INT) signals state changes on input pins and can be used to trigger events without continuous I²C polling.
Two devices can be used on the same I²C bus thanks to address selection via solder jumper. The module is equipped with dual QWIIC-compatible connectors for quick and reliable connection.
Features:
- Adds 8 GPIO ports via I²C
- Each port configurable as input or output
- Integrated level shifter
- High drive capability - directly control e.g. LEDs
- QWIIC connectors for fast and easy wiring
Specifications:
- Supply voltage VCCi: 1.65-5.5 VDC (I²C side)
- Supply voltage VCCp: 1.65-5.5 VDC (port side)
- Max current per port: 25 mA (sink) / 10 mA (source)
- I²C speed: 100 kHz / 400 kHz
- I²C address: 0x20 (default) / 0x21 (via solder jumper)
- Dimensions: 26 x 18 mm
- Mounting holes: 21 mm c-c / Ø2.5 mm
Connections:
- VCCi / GND - Power supply for I²C side
- VCCp / GND - Power supply for I/O ports
- SDA / SCL - Serial data and clock for I²C communication
- RST - Reset input (active low)
- INT - Interrupt output (open-drain, active low)
- IO0 - IO7 - Eight user-configurable ports (default as inputs on startup)
When using the QWIIC connectors, the VCCi and GND pins do not need to be connected separately. 10 k pull-up resistors for SDA and SCL are included on the board and can be disabled via solder jumpers on the backside.
Conclusion:
The TCA6408A is an excellent choice for projects requiring more GPIO ports than the primary microcontroller can provide. Its integrated level shifting makes it especially useful in systems with mixed logic levels. With high reliability, straightforward integration, and competitive pricing, the EKM017 is a highly functional and versatile addition to any I²C-based system.
