From 8944e2104d27459dc2626d78212042d241973e1c Mon Sep 17 00:00:00 2001 From: Kevin O'Connor Date: Mon, 11 Dec 2017 18:15:59 -0500 Subject: [PATCH] docs: Add FAQ item on AVR watchdog restart failures Signed-off-by: Kevin O'Connor --- docs/FAQ.md | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/docs/FAQ.md b/docs/FAQ.md index 76307d96..58487e62 100644 --- a/docs/FAQ.md +++ b/docs/FAQ.md @@ -124,3 +124,18 @@ rates, but the stepper motor may not have sufficient torque to move at a higher speed. So, for a Z axis with a very precise step_distance the actual obtainable max_z_velocity may be smaller than what is configured in Marlin. + +### When I set "restart_method=command" my AVR device just hangs on a restart + +Some old versions of the AVR bootloader have a known bug in watchdog +event handling. This typically manifests when the printer.cfg file has +restart_method set to "command". When the bug occurs, the AVR device +will be unresponsive until power is removed and reapplied to the +device (the power or status LEDs may also blink repeatedly until the +power is removed). + +The workaround is to use a restart_method other than "command" or to +flash an updated bootloader to the AVR devices. Flashing a new +bootloader is a one time step that typically requires an external +programmer - search the web to find the instructions for your +particular device.