The output pins produce a PWM or GPIO signal that is used to move the different servos of the platform.
The acronym PWM corresponds to Pulse Width Modulation. The autopilot sends a pulse with a certain width that is received by the servo, and according to the width of such pulse, the servo moves to a position or another. A wide pulse will correspond to a big movement and a narrow one to a small movement.
The Min and Max parameters are the pulse width values that will make the servo go to its lowest and highest position. As an example let’s consider the servo of an aircraft elevator, a pulse send by Veronte of 0.9 ms will correspond with the lowest point of the servo range (-30 degrees for example). On the other hand, a pulse of 2.1 ms will make the servo go to its top position (for example 30 degrees).
The option duty cycle is a different way of indicating the pulse width. Now the value indicated is a percentage which corresponds to the relation between the pulse width over the total period of the sent signal. So a 100% duty cycle will correspond to a signal with a constant value of 1, while a 0% duty cycle implies a constant signal with value 0. Between this two extremes the pulse width can vary as in the examples shown in the following figure.
The option “Servo” is used to select which servo of the platform will be wired to that pin of Veronte connector, so the signal sent through that pin will go to it.
The option “Frequency” determines the period of the pulses send by the autopilot. The PWM are built in pairs inside the autopilot, and that is why the frequency is indicated in pairs, i.e when the frequency of PWM 1 is changed, the one of PWM 7 also changes. The following table shows the PMW pairs as configured in Veronte autopilot.
|PWM 1||PWM 7|
|PWM 2||PWM 8|
|PWM 3||PWM 9|
|PWM 4||PWM 10|
|PWM 5||PWM 11|
|PWM 6||PWM 12|
A GPIO (General Purpose Input/Output) is a generic pin that can be configured as an input or output pin.When this option is selected on an output pin, the value sent is different as in the case of a PWM. Now, the pin admits 4 different states: ON (a continuous signal of value 1), OFF (a continuous signal of value 0), PULSE ON (a single pulse of value 1, with a width specified in seconds) and PULSE OFF (a single pulse of value 0, with a width specified in seconds). The configuration of the pin output value is done with an action “Output” in the automations section (visit 6.6).
To sum up, a PWM is a signal which consists of a series of pulses having a width determined by a percentage over a range specified by the parameters “Min” and “Max”. On the other hand, the GPIO is a signal with a constant value (1,0) or with a single pulse (1,0).