I2C SDA, SCL held high

[projnikdroid]

Posted on April 08, 2014 at 15:37

 I m working on STM32F303. I have interfaced I2C2 to EEPROM and DS3231 with pullups on SDA and SCL..

Issue: After Reset, SDA and SCL line is held high (it only happens ocassionally)..While I2C works properly, i can access both(EEROM and DS3231)

[Tesla DeLorean]

Posted on April 08, 2014 at 15:59

The pins are pulled high, the idle state of I2C is high, the problem is what?

[projnikdroid]

Posted on April 08, 2014 at 16:03I2C not responding... i guess it cant communicate with any of the above(some times)..After Reset, at times it works, or not.(works)

[projnikdroid]

Posted on April 08, 2014 at 16:06I2C not responding... i guess it cant communicate with any of the above(some times)..After Reset, at times it works, or not.(it works : I2C works (i can read data) ) else it hangs, in debugging it shows STOPF and NACKF bit set in ISR Reg

[Tesla DeLorean]

Posted on April 08, 2014 at 16:20

The I2C implementation on the STM32's is UGLY, there are conditions depending on how (order) you bring up the pins, that the peripheral will see a LOW pin and enter a BUSY mode. Is that what you're talking about? What status is the peripheral reporting in this condition?

Also chips hung on the I2C bus often don't have a RESET, if they get hung in an odd state you might need to clock them out manually.