We have had several instances of our product get stuck in in a reboot loop but have never been able to diagnose the issue because we didn’t have UART console access enabled when the issue occured, until now that is. I managed to capture the follow trace which appears to denote the I2C is busy but y…

Hey Darren, Sorry to hear this bug is still around. I’ve always suspected this is a bug somewhere in either: a) the low power MCU inside the WP85 module (I believe it’s on the stuck address 0x3a but scan the bus to be sure) b) the driver for the Qualcomm Universal Peripheral Engine (QUP) i2c adap…

Hey @dbeckwith , This patch makes some critical additions to the QUP i2c adapter driver, specifically around the bus busy issue, so I would be very surprised if this did not help. I compiled it for my mangOH Red and I’ve only seen a positive result so far. I believe the ADC on the mangOH is implemen…

hi @dbeckwith , can you provide logs when you face the issue, please? BR

@plu Sorry for the delay here are the logs with the extra debugging you asked me to run. I have removed our our app logs for the moment. Please let me know if you need additional details. I2C Lockup Debug Oct 24.log.zip (280.3 KB)

The source I2C bus lock up turned out to be the LTC2942 battery gas gauge. The SDA pin is stuck low on boot. I have contacted Analog Devices regarding this issue but there suggestions didn’t correct the issue. What’s interesting is the LTC2942 SDA line comes high after some clock cycles on the bu…

Fantastic work @dbeckwith , thanks for sharing. Were you ever able to get a reading from the LTC2942 sensor?

@nvd Yes, when the unit booted properly I was able to get a readings from the LTC2942.

Did you solve the problem of LTC2942 above?

Hi, No I did not. I just stopped using it.

Legato Stuck In Reboot Loop Due To Stuck I2C

Legato Application Framework

dbeckwith October 2, 2019, 4:05pm 3

Any thoughts on this issue? I was pointed to this post as the possible cause WP8548 I2C bus lock up when read ADC2 and ADC3 - #9 by plu but I’m not reading the WP85 ADC.

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Legato Stuck In Reboot Loop Due To Stuck I2C

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