(2025-10-13, 12:02 AM)jacqueline Wrote: Hi! What is pin 3 (EN) on U4 (the 3v3 regulator) reading? The 3V3 power supply isn't normally enabled until the lock switch is pulled high, and then from that point the SAMD21 holds it up until it's time to power down.The EN pin on U4 has almost no voltage (0.15V), and even the sys_power pin has no voltage (0.01V). However, both VBUS_SWITCHED and VBUS are outputting around 5V normally. Is this a problem with the MCP73871? (I've checked that the problem isn't caused by a poor solder connection on the MCP73871.)
After extensive testing, I've discovered that even with a 2-pin 3.7V lithium battery and a Type-C power supply, there's still no SYS_POWER or 3V3 output, no BAT_LEVEL voltage, and CHG_SEL is low. These aren't issues with the ATSAMD21E18A or its software, right?
