status_led.c

Overview

Show that the update window is open, on the board itself. The window is the entire authorization model for an update, and until now it was invisible. Three things open it -- SW2, Apple Home's "Turn On Pairing Mode", and the bench SWD write -- and none of them gave the board any way to say so. An owner who pressed the button could not tell whether the press had registered, and the five minutes could run out while they were still finding the phone. The only feedback was a log line on a debugger that a released board does not have attached. D10, the blue one, at 2 Hz. Blue because the other three are the DW3000's own colours by convention on this board (D13 is tx red / rx green) and a fourth red would read as a fault; 2 Hz because a slower heartbeat reads as "alive" rather than "waiting for you", which is the wrong message for something that expires. It follows the window rather than the button, so it is honest about the state that actually matters: it goes out when the window expires on its own, not when someone stops pressing.

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