I2C, SPI or UART: How do I choose the right connection for sensor and development plate?
I2C, SPI and UART are different methods of connecting devices. The choice should be determined by the actual interface of the module and the requirements of the project, not just the number of free wires.
What to check out
- I2C is convenient for several slower peripheral devices with different addresses. Check pull-up resistance, tension and capacitance connection.
- SPI is suitable for rapid data exchange, for example by SD-card. Devices normally need a separate CS signal and a harmonised transmission mode.
- UART uses broadcasting and reception that you correctly cross-connect. They must match speed, data format and signal levels.
- For longer connections in a disturbed environment, consider a dedicated physical interface and protection.
A Practical Example
On the same panel, OLED can use I2C, SD-card SPI and external controller UART. Before binding, prepare the connector table so that functions do not overlap.
Common error
TTL UART is not directly RS-232 or RS-485. Modbus also describes the protocol, not automatically the electrical compatibility of the connector.
For further reading
- Espressif: I2C interface documentation (English). Detailed example of one of three interfaces: I2C settings and data transmission.
Compatibility check products
Select products according to the above criteria; the list is not a confirmation that they are all interchangeable.
Published:
20.10.2026
