I’ve been playing around with ultra low power mode on the mangOH Yellow and have noticed some strange behaviors. I’m trying to troubleshoot an issue with a custom IoT module and I found these weird symptoms. I was wondering if anyone has any ideas what’s going on here.
Without any IoT card inserted – if you touch the mangOH Yellow in the area near the power switch when it’s in ULPM, the power light blips on 3 times in approximately 1 second intervals. It looks like VCC_5V0 is trying to turn itself back on?
With the custom IoT card inserted – sometimes the LEDs on the mangOH Yellow board stay on after it enters ULPM. It looks like maybe VCC_5V0_EN is floating or something? I noticed that enable line ends up going directly to a GPIO pin on the WP7702. Does the WP7702 maintain the GPIO output states when it’s in ULPM? I couldn’t find a good answer to that question in the product specification document.
Thanks for any ideas,