All the necessary connections will be made on the blank board. The board wiring I present below is a good guide to construction.<\/p>\n\n\n\n
In the photo below you can see the DC motor I chose to use. As you can see it has a built-in encoder. It is up to you whether you want to use it as a simple DC motor or if you want to use the encoder or finally use the motor and the encoder together. <\/p>\n\n\n\n Engine Engine wiring: In our first construction we will use only the engine encoder to understand its operation. As you can see in the image below, the motor power cables, which are Red and White, are not connected. Only the encoder cables are connected. We will rotate the motor shaft by hand and monitor the signals generated.<\/p>\n\n\n\n An encoder works by observing changes in the magnetic field generated by a magnet attached to the motor shaft. Here you will find the principle of operation of the sensor based on the HALL<\/a> effect .<\/p>\n\n\n\n As the motor rotates the encoder outputs will be activated periodically. When the magnet is rotated clockwise, output “A” will be activated first and when rotated counterclockwise, output “B” will be activated first. This way you know exactly when the motor shaft rotates. This can be very convenient for cases where we need to control the forward or backward movement of a DC motor. The following figure shows the wiring for two identical engines on an Arduino UNO board. Other equipment will be connected to this board later. We will use in our example only the encoder from one engine. Let’s write a very simple program to understand how a coder works and how to read the coder outputs. In the monitoring of the serial port we observe the following results.<\/p>\n\n\n\n![\"\"](\"https:\/\/avlos.gr\/wpress\/wp-content\/uploads\/2025\/10\/motor_2.jpg\")
JGB37-520 DC motor with mechanical gearbox and encoder.
It is mainly used in variable speed cars, self-balancing cars (with two wheels), racing cars, monitoring car, robots and other related constructions.<\/p>\n\n\n\n
The speed encoder operates using the Hall<\/a> effect .<\/p>\n\n\n\n
1, red: motor power supply + (polarity to white reverses motor drive)
2, black: encoder power supply –
3, yellow: signal line, (A)
4, green: signal line, (B )
5, blue: encoder power supply +
6, white: motor power supply – (alternating polarity with red reverses motor drive)<\/p>\n\n\n\n![\"\"](\"https:\/\/avlos.gr\/wpress\/wp-content\/uploads\/2025\/10\/motor_1.jpg\")
The following diagram shows the phase difference between outputs A and B of the encoder. We will programmatically exploit this phase difference to control the motor movement.<\/p>\n\n\n\n![\"\"](\"https:\/\/avlos.gr\/wpress\/wp-content\/uploads\/2025\/10\/DC_motor_3.jpg\")
It can be seen that there are two connectors for each motor, one for Motor A and one for encoder A. In this example we will only use the Encoder A
connector. Four connectors are connected to this connector. The two ends are for powering the encoder, GND and VCC. The two middle ones are connected one to pin D2 and the other to pin D10. Note here that pins D2 and D3 are the only ones used to create interrupts on the Arduino UNO<\/a> board. We will encounter this when writing the program.<\/p>\n\n\n\n![\"\"](\"https:\/\/avlos.gr\/wpress\/wp-content\/uploads\/2025\/10\/note_2.jpg\")
To read the encoder, we will connect the encoder output pins to the Arduino terminals 2 and 10. Pin 2 is an interrupt pin. The encoder power cables will be connected to the Arduino 5V and GND. <\/p>\n\n\n\n\/\/Author : Manolis Aristovoulidis\n\n\/\/I spin the motor by hand and measure and print\n\/\/ the speed and direction of the movement\n\/\/positive numbers represent clockwise movement,\n\/\/negative numbers represent counterclockwise movement\n\nconst byte encoder_pinA = 2; \/\/A pin -> the interrupt pin 2\nconst byte encoder_pinB = 10; \/\/B pin -> the digital pin 10\n\nint pulses; \/\/the number of the pulses\nboolean Direction; \/\/the rotation direction\n\n\nvoid setup()\n{\n Serial.begin(57600); \/\/Initialize the serial port\n EncoderInit(); \/\/Initialize the module\n}\n\nvoid loop()\n{\n Serial.print(\"Direction:\");\n if(Direction){\n Serial.print(\"Forword \");\n }else{\n Serial.print(\"Backword \");\n }\n Serial.print(\"Pulses:\");\n Serial.println(pulses);\n pulses = 0;\n delay(100);\n}\n\nvoid EncoderInit()\n{\n Direction = true; \/\/default -> Forward\n pinMode(encoder_pinB,INPUT);\n attachInterrupt(digitalPinToInterrupt(encoder_pinA), wheelSpeed, RISING );\n}\n\nvoid wheelSpeed()\n{\n int val = digitalRead(encoder_pinB);\n if(val == LOW ){\n Direction = false; \/\/Reverse\n pulses--;\n }else{\n Direction = true; \/\/Forward\n pulses++;\n }\n }<\/code><\/pre>\n\n\n\n