I2C question

BradC

G'day guys,

If I want to use one of the I2C lines as an output, is it safe to toggle the SCL line with reckless abandon provided I keep the SDA line pulled high?

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"Are you suggesting coconuts migrate?"

Cluso99

You can do either and it will be OK. That is how I share on the TriBlade. On the RamBlade I have to disable the clk line to the eeprom.

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Peter Jakacki

I use the SCL and SDA as general clock and data out but not in. If you think of the I2C START an STOP condition as a "chip select" then you know that as long as you don't have a chip "selected" then it doesn't matter what happens on the clock and data. If though you are clocking out data for something else just make sure you don't change the data line while the clock is high as this is how I2C devices sense the START and STOP. That's why I only use the data line as an output as I can't really control what some devices might send back (unless I can).

So a typical application might be clock and data to shift-registers with a separate I/O pin to load the registers. Even the SD card's clock and data in can be the I2C lines and then all you need are 2 other I/O.

Anyway, what's the application?

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*Peter*