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Forum Index : Microcontroller and PC projects : I2C with internal Pull Up
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atmega8 Guru  Joined: 19/11/2013 Location: GermanyPosts: 727 |
Hi, is it possible to use the new internal pullup Feature with I2C? What is the resistor value of the internal Pullups/pulldowns? THX |
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9745 |
I may well be wrong, but my understanding is that the internal pull-ups are 10k - I may be wrong on that value, but I seem to remember reading that - somewhere! 
Assuming that I am right there for a moment, then 10k pull-ups on I2C would PROBABLY be a little high, and would likely allow noise onto the bus, which would not be a good thing. The standard value seems to be 4k7 in just about anything I have seen, with the really super-high-speed 1Mb I2C stuff having 1k pull-ups as would seem to be norm. (but the uM does not support that kind of speed) Other members will chime in here with their thoughts I imagine. Auf Wiedersehen. Smoke makes things work. When the smoke gets out, it stops! |
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Geoffg Guru Joined: 06/06/2011 Location: AustraliaPosts: 3308 |
The internal pullups in the MX170 are about 100K. Way too low for I2C. Geoff Graham - http://geoffg.net |
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