WT-220 Status LED States
Off ➡️ On ➡️ Booted ➡️ Shutdown Requested ➡️ Shutting Down ➡️ Power Off
LED states on WT-220 rear panel PCB. SAMD controls power to Pi via MOSFET. Pi listens for shutdown request from SAMD (button) via I2C and acts on request by shutting down Raspbian. Last systemd target then sends I2C command to turn off 5 V to Pi.
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