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Issue when doing i2c and ADC on ADuC7126

Question asked by shane91773 on Sep 7, 2013
Latest reply on Oct 17, 2013 by furbanc

Hello,

 

I have a strange issue in my ADuC7126 firmware that cause a intermittent glitch on an I2C dac.  I'm using RTX provided by Keil but don't think it has anything to do with an RTOS.  In my code, I have one task sampling ADC0 to ADC7 and wraps around once it reaches the end.  In another task, I'm interfacing with an I2C temp sensor and a 4 channel DAC in a round-robin fashion.

 

Once in a while, the DAC output would go to 0 briefly for no reason.  When I setup the oscope and captured the both I2C line and trigger when the DAC output goes to 0, the data that went to the DAC isn't what I sent.  The DAC basically shut down because it couldn't understand what was sent to it.  However, when I disabled the ADC task, the I2C DAC problem goes away.

 

Can anyone shed some light as to why disabling ADC would cause the problem go away?

 

Thanks,

Shane

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