partially worked microdrill

microdrill/README

@@ -10,48 +10,29 @@ again and returns back on next pulling up.
 
 If drill motor was off, pressing footswitch will also turn it on.
 
-/*
- * the behaviour of steps counter depends on footswitch state; timer
- * setup varies due to varistor value.
- */
-
+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) used to setup the zero point of drill: 
-	- drill quickly moves up
-	- stepper speed changes to lowest
-	- while pressing down the footswitch motor moves down
-	- on footswitch release motor stops at current position
+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
 
-/*
- * Button control: by default, EXTI interrupts serve buttons.
- * To avoid clash, EXTI interrupt handler sets the special flag 
- * value to 50 (in milliseconds) and turns off EXTI IRQ.
- * In the main() body the endless cycle checks value of system
- * timer variable changed by system timer once per millisecond.
- * If the EXTI pause flag non-zero, it decrements it until zero.
- * After that EXTI turns on again and keys state occured. This
- * allows also to avoid some noice on MCU inputs.
- */
+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
 
-2.2. Right button (BTN2) used to switch between regulation
-of stepper speed or drill speed by variable resistor on tray's
-control. The default state is stepper (vertical) speed regulation.
+2.3. Simultaneous pressing of both buttons will stop drill motor
 
-Drill works with algorithm of automatical moment correction:
-if drill stalled, the PWM duty reduced until current through drill's
-winding stabilize to max value. Conversely, when current through winding
-falls to very low value, PWM duty increased until normal current
-value. Varistor allows you to set these limiting values in drill speed
-mode.
 
-2.3. Simultaneous pressing of both buttons will:
-	- stop drill motor
-	- move tray up
-	- move drill down
+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.
 
-So, you can easily change drilling bits. After that press again BTN1+BTN2
-to return tray down & drill motor up. After this operation the uppest
-drill's position will be zero.
+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.