13. Servo SG90 (180° / 360°)¶
13.1. Introduction¶
The SG90 servo motor is a tiny and lightweight motor which can perform different angle adjustment (180° servo) or rotation control (360° servo).
13.2. The principle¶
The Servo motor operate base on the PWM signal, the action of servo motor will following the input signal’s duty cycle.
The SG90 designed duty cycle (pulse length) is 500µs to 2500µs, during this range, the duty cycle will be representing different meaning.
180° Servo¶
For 180° Servo, the duty cycle will represent to the position
| Duty cycle(us) | Degree |
|---|---|
| 500 | 0° |
| 833 | 30° |
| 1166 | 60° |
| 1500 | 90° |
| 1832 | 120° |
| 2165 | 150° |
| 2500 | 180° |
360° Servo¶
For 360° Servo, the duty cycle range is different, and the meaning represent to direction and speed
| Duty cycle(us) | Direction | Speed |
|---|---|---|
| 1000 | clockwise | 100% |
| 1166 | clockwise | 60% |
| 1333 | clockwise | 30% |
| 1500 | N/A | stop |
| 1666 | anti-clockwise | 30% |
| 1832 | anti-clockwise | 60% |
| 2000 | anti-clockwise | 100% |
13.3. Specification¶
Operating voltage: 4.8V (~5V)
Weight: 9g
Operating speed: 0.1 sec / 60 degree
Stall torque: 1.8 kgfcm
Interface: PWM signal
PWM period: 20ms(50Hz)
Duty cycle: 500µs ~ 2400µs
Operation degree: 0~180° (180° Servo) / N/A (360° Servo)
Temperature range: 0 ~ 55°C
13.4. Pinout Diagram¶
| Pin | Function |
|---|---|
| G | Ground |
| V | Voltage Supply |
| S | Input (PWM signal with duty cycle) |
13.6. Determine the type of servo (180°/360°)¶
Look at the side that have cable pull out, checking there have a variable resistor or not.
If have “green variable resistor”, that is 180° servo.
Otherwise, that is 360° servo.
13.7. Quick to Start/Sample¶
Connect the sensor to development board (direct plugin or using wire)
Open Makecode, using the https://github.com/smarthon/pxt-smarthome PXT
The extension contain two functions that provide convenience to set the specific position or rotation.
For 180° Servo, you may control that turn to specific degree position
Use the
Turn 180° Servo to 135 degree at P1to make it to turn to 135° position
For 360° Servo, you may control that turning in specific direction and the rotation speed
Use the
Turn 360° Servo with clockwise direction speed Level 3 at P1to make it rotate at max speed and clockwise direction.
13.8. Result¶
If you using 180° servo with the corresponding program, after the button A is pressed, the servo will turn to the 135° position.
If you using 360° servo with the corresponding program, after the button B is pressed, the servo will keep rotate in clockwise direction with max speed.
