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Topic: Wire.h and timer interrupts (Read 902 times) previous topic - next topic

chuck_c

Hello,

I am trying to read an ADXL accelerometer via I2C using the Wire library at regular intervals.  A periodic interrupt to fill a global buffer seems like a reasonable solution, but calls to Wire.endTransmission() crashes if called from within an interrupt service routine.  The amount of data I am reading is pretty minimal and the read takes only about 1 millisecond.  I am running the ISR at intervals of about 10 msec, so I think timing is not a problem.

Does anyone have ideas about why the Wire library and ISR might interfere with on another?  Thank you,

Charles

SteNull

Hi.
I  have the same problem, want to read from I2C inside an ISR. I found out that Wire use interrupts and inside an ISR interrupts are disabled.
Would be nice to find a solution to this but my knowledge in this subject is not so great  :-/

Ran Talbott

If your loop() routine is fairly short,  and you don't need really precise intervals between readings,  you could have the ISR set a global variable,  and take a reading in loop() when the flag is set.


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