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maarten-pennings / iAQcore

Arduino library for the iAQ-core indoor air quality sensor module with I2C interface
MIT License
15 stars 7 forks source link

Pull Up Resistors #3

Open abrahamMLG opened 5 years ago

abrahamMLG commented 5 years ago

Hi Maarten!! just read IAQ-core P datasheet from AMS ans they talk about use 4k7 Ohms resistors with SDA / SCL and VCC. I want to mount one IAQ and would know if u use the resistors berfore mountig. Resistors are not in your wiring and i'm not sure if ther are necesary or not.

Regards

maarten-pennings commented 5 years ago

Hi @abrahamMLG, officially you do need those so called pull-up resistors. They ensure the lines are high by default.

The value of the resistors actually depends on the clock speed, the amount of slave devices, the length of the sda/scl wires etc.

In practice, most mcu's do have pull-up resistors inside, which are sufficient. Not having them won't physically break anything, at worst you have unreliable communication.

If you are lazy (like me) leave them out, and only add them if you have communication problems.

If you have them and want to play save, add the pullup resistors.

If you are a top-notch designer, compute the value of the pull-ups you need :-)

abrahamMLG commented 5 years ago

HI again, thanks for your quick answer, i trust you... ;P, tomorrow I'll weld the cables and start the tests, hope it works better than the CCS811. Thank you so much for everything.

maarten-pennings commented 5 years ago

Hi @abrahamMLG, is it working, can we close the issue?