Analogue to PWM Configuration

In this tutorial explains the calculations for converting an analogue value from a potentiometer into a PWM value corresponding to the same angle for a servo motor, as described in this tutorial and video: Youtube RoNeX Interfacing Video Code & Explanation

From the range of rotation of our potentiometer and resolution of the RoNeX ADC we know:

Potentiometer rotational range = 0 - 300°
12 bit Analogue input channel range = 0 - 4095
Analogue value at 180° = 4096 / 300 * 180 = 2457.6

From the Servo Datasheet we know:

Servo works on a 20ms control period.
On time of 0.5ms corresponds to an angle of 0°.
0.5ms on time in 20ms period corresponds to 2.5% duty cycle.
On time of 2.5ms corresponds to an of 180°
2.5ms on time in 20ms period corresponds to 12.5% duty cycle.

From the RoNeX Manual we know:

RoNeX base clock frequency  = 64MHz.
Master clock divider = 20.
Resultant master clock frequency = 64MHz/20 = 3.2 MHz.
PWM Period = 64000
Output frequency = 3.2MHz/64000 = 50 Hz
50Hz corresponds to period of 20ms.

From this we can deduce that:

In a 64000 period, 2.5% duty cycle = 64000 * 0.025 = 1600.
In a 64000 period, 12.5% duty cycle = 64000 * 0.125 = 8000.

For ease of calculation we offset the pwm_on_time by -1600 to give a range of 0-6400. This gives rise to the following conversion constant:

PWM range / Analogue range  = 6400 / 2457.6 = 2.6042

Which is then apparent in the code Python:

pwm.pwm_on_time_0 = int(2.6042*analogue[0] + 1600)