STM8_samples/microdrill

Algorithm

1. Main functionality - footswitch

By pressing footswitch you move drill down. Speed setup produced
by variable resistor on tray's control. Pulling footswitch
up returns drill into its previous position. If you press down the
footswitch when drill haven't reach its starting position, it moves down
again and returns back on next pulling up.

If drill motor was off, pressing footswitch will also turn it on.

If you pull down the footswitch when one of the tray buttons pressed, the
tray will move up or down.

2. Tray buttons

2.1. Left button (BTN1) 
	- press it and rotate potentiometer to change drill speed
	- press both buttons to stop the drill
	- press footswitch when it pressed to move tray

2.2. Right button (BTN2)
	- press it and rotate potentiometer to change stepper speed
	- press both buttons to stop the drill
	- press footswitch when it pressed to move tray

2.3. Simultaneous pressing of both buttons will stop drill motor


The stepper's speed changes depending on current in drill motor. If it is too big,
the stepper paused until current will fall. The idle motor motion (upwards) done
on biggest speed.

To change the drill bit just press one of the tray buttons and push down the
footswitch. The tray will go up. To move it down press tray button and footswitch
again.