Calibration

While nominal values of 1.0 msecs for LOW and 2.0 msecs for HIGH may be considered industry norms for radio control equipment, the fact is that different brands have varying values.  Consequently, it makes a lot of sense to have an auto-calibration routine that lets the user find the LOW and HIGH points of the particular system.

Credits:  The concept was first learned from Michele Schieppati and reinforced by Cats Eyes and TugBoat.

This routine can be inserted in the front end of any piece of PIC code.  The basic idea is that the user puts a jumper on Pin 6 to ground it. Then when power is applied to the PIC, GP1 reads as zero.  This condition branches the code to the  calibration routine.  The user sets the stick to LOW position and watches the LED blink 5 times. When it stops blinking the averaged LOW value is stored in PIC non-volatile memory.  The user then moves the stick to HIGH position and then LED blinks 5 times.  The averaged HIGH value is stored in non-volatile PIC memory.  The user then turns off the power and removes the jumper.  From then on, the PIC knows the LOW and HIGH values by reading them from memory.

Note:  A different version of auto-calibration is offered in Twin Power Mk2 - where all the pins had been used up and an innovative method used to jumper an existing pin assignment.

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Last modified: March 18, 2004