I2C safe bus length

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PL_aus
 
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Joined: Sat Sep 03, 2022 2:42 am

I2C safe bus length

Post by PL_aus »

Hi,
I would like to use the Adafruit TMP117 breakout board, connecting to a Pimoroni Automation 2020 W board https://shop.pimoroni.com/products/auto ... 2384464979
It would connect via the Qwiic/Stemma connector on the a2040w board.

I need to allow for at least 0.5 to 1m lead length between the a2040w board and the tmp117. The leads may run through parts of the existing equipment in which it is installed; e.g. air conditioner, heater, pump, etc. Possibley noisy environment due to fractional HP motors (maybe ECM motors), other boards in the equipment, 120~240VAC power to the equipment (no 3 phase), WiFi, etc.

Can I have error-free comms with those lead lengths?
What would be the best cable type to protect against noise?

My sample rate can be very slow - a read every 1-2 seconds is fine. I expect that the bus rate could then be the slowest allowable. There's two QWIICs on the a2040w and I would connect one tmp117 on each connector. Don't expect to have any other devices on either of the I2C busses, though its a possibility.

Can your related TMP117 libraries be used (or readily adapted for use) on the a2040w? FYI - Automation 2040 W library at: https://github.com/pimoroni/pimoroni-pi ... ation2040w

TIA

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dastels
 
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Re: I2C safe bus length

Post by dastels »

To handle distance you can use https://www.adafruit.com/product/4756. The related guide also has advice on noise reduction.

The Adafruit libraries should be fine.

Dave

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PL_aus
 
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Re: I2C safe bus length

Post by PL_aus »

Thanks Dave.

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