Module01.jpg

Supplier info

  • Operating voltage: 1.9-3.6V (recommended 3.3V)
  • Standby current: 60nA
  • Temperature range: -40 .. 85 Celsius (Recommended -10 .. 60 Celsius)
  • Temperature accuracy: circa 0.4 Celsius (-10 .. 85 Celsius)
  • Humidity range: 0..100% RH (recommended 20% .. 80% RH)
  • Humidity Accuracy: circa 3% RH (0..80% RH)
  • Temperature conversion time: 7ms
  • Humidity conversion time: 17ms (temperature conversion will occur automatically when the humidity conversion)
  • Interface Type: I2C 2.54mm pad pitch
  • Module size: 8.5mm X 10mm

Connections

Module02.jpg

Programming

The Si7021 has a fixed I2C address; hence you can only connect one Si7021 to a I2C bus. Use the TCA9548A multiplexer to connect up to 8 - which has the added advantage of voltage level conversion.

See https://github.com/LowPowerLab/SI7021

Or the MySensors version at https://github.com/mysensors/MySensorsArduinoExamples/tree/master/libraries/SI7021

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