case 08 servo
Introduction
The servo is a kind of angle servo driver. It is adapted to varying control system. In this case, we are going to use the micro:bit to control rotating of the servo.
Products Link
Hardware Connect
Connect circuit as above picture and put 2 AAA batteries into batteries pack.
Principles of Circuits
The GND of slot on micro:bit is into innards of batteries' GND to generate the current loop.
Introduction of Components
Servo
A servo is an automatic control system that consists of a DC motor, a reduction gear unit, a potentiometer and a control circuit. Generally, the servo has its the largest rotation angle (For example:180 deg).
Our reference point at a 90deg middle position is defined by a signal frequency of 20ms and a pulse width of 1.5ms.
The experiment box included a 180° servo.
Note: You don't need to think out some complex questions like pulse width because micro:bit Foundation has converted the servo code to block.
Note: Please note the positive and the negative when you are connecting.
Software
Step 1
Click makecode https://makecode.microbit.org/#。
Click on "New Project" and set a new Project.
Step 2
Snap the servo write pin and pause block into the forever and set P1 to 0. Pause 2000ms.
Snap the servo write pin again after the first pause block and set P1 to 180. Pause 2000ms.
Program
Program link：https://makecode.microbit.org/_fudJaMCRhE1r
You also could directly download program by visiting website as below:
Result
The servo will rotate between 0 deg to 180 deg.
Think
If we want to make a thermometer dial by using the NTC and the servo, how do we design the circuit and the programming?