These are I2C (Inter-Integrated Circuit):

• [ ] Spectrum Sensor
• [ ] Distance Sensor

  • [ ] Qwiic

    

  • [ ] SCL(A5:only clock communication)

  • [ ] SDA(A4:only data communication)

  • [ ] “Multiplexer”: diversifying the pin

• [ ] UV Sensor
• [ ] Loudness Sensor

PWM

PWM is not a protocol, it stands for Pulse Width Modulation, used for dimming LEDs, motor speed control, switching power supplies, etc. I2C indeed is a protocol.

• [ ] Occupancy Sensor(Sense energy emited)

Variable Resistors

• [ ] Moister Sensor
• [ ] …

SPI

• [ ] Humid Sensor
• [ ] Distance sensor(wide arange)
• [ ] Memory Card