![\"\"](\"http:\/\/www.igfasouza.com\/blog\/wp-content\/uploads\/2020\/10\/duke-raspberry.jpg\")
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What’s up?<\/b><\/p>\n
This post is to show how I created a Java Duke Servo demo with a Raspberry Pi. This is another blog about Java on Raspberry Pi.<\/p>\n
Interfacing a Servo Motor with Raspberry Pi is an interesting topic as Servo Motors are the main components of a Robot and with the help of Raspberry Pi, you can have endless opportunities in Robotics.<\/p>\n
Because today we celebrate children’s day in Brazil, I came with the idea to show this simple robot example using a servo motor and a Raspberry Pi. And nothing better than a Java Duke servo demo to show Java on Raspberry Pi.<\/p>\n
Using a cardboard and Duke image to create a servo demo where Duke moves his arm.<\/p>\n
![\"\"](\"http:\/\/www.igfasouza.com\/blog\/wp-content\/uploads\/2020\/10\/duke.jpg\")
\nI used this image to create my demo.<\/p>\n
To control a Servo Motor, you need to use a technique called Pulse Width Modulation or PWM. In PWM technique, you will be sending a pulse of variable width and the position of the Servo Motor\u2019s shaft will be set by the width or length of the Pulse.<\/p>\n
Nice \u201cPulse Width Modulation<\/em>\u201d explanation here<\/a> <\/p>\n The frequency of the PWM signal is a fixed value and is dependent on the type of Servo Motor. When the pulse width of the PWM Signal is 1ms, the position of the servo is the left. The Duty Cycle of this position is (1ms\/20ms) x 100 = 5%.<\/p>\n Similarly, for pulse widths of 1.5ms and 2ms, the position of the servo is middle (with a duty cycle of 7.5%) and far right (with a duty cycle of 10%).<\/p>\n Note<\/strong>: Be aware here that you need to test and check your servo. You might need to calibrate this number for you.<\/p>\n I\u2019m using the SG90 servo motor and you can check the Datasheet here<\/a>.<\/p>\n The Tower Pro SG90 Servo Motor Consists of three Pins: PWM (Orange or Yellow), VCC (Red), and GND (Brown). The VCC and GND pins must be connected to +5V and GND of the power supply.<\/p>\n PWM or Signal Pin of the Servo Motor must be connected to the PWM Output of the Controller (Raspberry Pi). Based on the width of the Pulses from the PWM signal, the angle of the Servo Motor\u2019s shaft will vary.<\/p>\n 1ms pulse for 0 degree (LEFT)
\nAt 50Hz i.e. a period of 20ms, the minimum pulse width is 1ms and the maximum pulse width is 2ms. Most servo motors can have a swept area of 180 degrees i.e. 90 degrees on either side of the neutral position.<\/p>\n![\"\"](\"http:\/\/www.igfasouza.com\/blog\/wp-content\/uploads\/2020\/10\/Untitled-drawing.jpg\")
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Schematics<\/h2>\n
![\"\"](\"http:\/\/www.igfasouza.com\/blog\/wp-content\/uploads\/2020\/10\/schematics_pi.png\")
<\/p>\n![\"\"](\"http:\/\/www.igfasouza.com\/blog\/wp-content\/uploads\/2020\/10\/schematics.png\")
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\n1.5ms pulse for 90 degree (MIDDLE)
\n2ms pulse for 180 degree (RIGHT)<\/p>\nPI4J<\/h2>\n