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Sensirion / raspberry-pi-i2c-scd4x

RaspberryPi driver for Sensirion SCD4x sensors
BSD 3-Clause "New" or "Revised" License
20 stars 9 forks source link

Connection #4

Closed BootNeos closed 3 years ago

BootNeos commented 3 years ago

I am totally confused about the 'pull-up-resistor-topic'. Your image shows, that it is possible to connect the SCD41 directly to the I2C-Pins of the Raspberry Pi. This leads to my question: Is it right, that no extra pull-up resistors are needed? (Except the 1.8k ones in the raspberry pi) Therefore, 1.8k is enough? (In the datasheet, 10k is suggested)

Many thanks in advance.

MBjoern commented 3 years ago

Hi BootNeos

The Raspberry Pi should have internal pull-up resistors taking care of this point. In my experience, hooking up the SCD41 directly to the i2c pins as depicted in this repository works very well.

I hope that helps Best regards Björn

BootNeos commented 3 years ago

Okay, thanks! :)

Best regards

rnestler commented 3 years ago

Just for clarification in case anybody lands at this issue:

Therefore, 1.8k is enough? (In the datasheet, 10k is suggested)

1.8kΩ is a lower resistance than the 10kΩ from the datasheet, so the pull (and thus current consumption) is stronger. See also https://www.i2c-bus.org/i2c-primer/how-i2c-hardware-works/