Apply config changes, tweak comments, next_ping_ms => next_idle_ms

[thinkyhead]

Recent changes were made to prevent watchdog timeout in very long arc moves. This involves calling idle() every 200ms. A side-effect of this call is some stuttering during arcs. This PR addresses the issue by only calling idle() once out of 4 times, while only calling thermalManager.manage_heaters() (which also resets the watchdog timer) the other 3 times.

[AnHardt]

An alternative could be to call thermalManager.manage_heaters() unconditional. If will return immediately if no update is required. Or to use if (!temp_meas_ready) for the condition to call thermalManager.manage_heaters().

Marlin/Marlin/temperature.cpp

Line 710 in dee6322

if (!temp_meas_ready) return;

Finding an alternate condition for idle() is much harder. For manage_inactivity() and checking the encoder ~1/second seems to be to slow, while display updates with 1Hz seem to be ok to me.

[thinkyhead]

Perhaps it should be made possible to lower the display refresh rate with a variable, so we can still call lcd_update to get controller knob and button events, but redraw the display only every half second (minimum).

[thinkyhead]

Trying this idea with both plan_arc and cubic_b_spline functions.

[AnHardt]

The time between display updates is aboute 1s. Changing the comment does not change the fakts.

-    if (currentMenu == lcd_status_screen) {
-      if (!lcd_status_update_delay) {
-        lcdDrawUpdate = LCD_DRAW_UPDATE_CALL_REDRAW;
-        lcd_status_update_delay = 10;   /* redraw the main screen every second. This is easier then trying keep track of all things that change on the screen */
-      }
-      else {
-        lcd_status_update_delay--;
-      }
-    }
+    // Simply redraw the Info Screen 10 times a second
+    if (currentMenu == lcd_status_screen && !(++lcd_status_update_delay % 10))
+      lcdDrawUpdate = LCDVIEW_REDRAW_NOW;

Why this ugly, slow modulo division?

[thinkyhead]

"Simply redraw the Info Screen 10 times a second"

I must have been lacking sleep or very stoned I wrote that. Obviously backward.

Otherwise, valid concerns. Please propose/contribute alternatives/improvements.
I have very limited time to attend to Marlin right now.