Wake up host computer

[ddrcode]

Right now the host can't be awake from Charon, and it feels impossible to do it the way as physical keyboard does it, as Linux simply disconnects from /dev/hidg0 when the hosts goes to sleep. The only option right now seems to be wake-on-lan.

• Configure host to accept WoL
• Test whether sending Magic Packet from Pi via WiFi works
• Add MAC address to Charon's config
• Add functionality that sends WoL when hid device not available and user presses any key.

To send WoL in Rust:

use wake_on_lan::MagicPacket;

let packet = MagicPacket::new(&[0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX]).unwrap();
packet.send().unwrap();

Explore USB options

Still it's worth to explore the alternatives. Perhaps there is a way to send some data to USB port on the lower level, bypassing the need for hid devices.

Internet resources

• RP forum: How can I wake up my computer with my Raspberry Pi Zero W?
• RP GH issue: Raspberry Pi Zero in HID Gadget Mode Cannot Wake Host Computer – many suggestions here and claimed-to-be-working patches.
• Kernel patch: solution that claims to be working
• Another patch with explanation (Japanese)
• rpizero-linux-build - tool that helps build patched kernel for RP

[ddrcode]

So far WoL is being sent on specific key combination (F8 in my case, but configurable), rather than any key. In such case I don't need to monitor whether hidg is lost or not.

See:

• wake_host_on_lan function
• usage of the above