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Motor Speed Sensor Module Circuit Circuit T.K. HAREENDRAN (HTTP://WWW.ELECTROSCHEMATICS.COM/AUTHOR/HAREENDRAN/) (HTTP://WWW.ELECTROSCHEMATICS.COM/AUTHOR/HAREENDRAN/)
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Here is a motor mot or speed sensor module, the major go al is to check the rate of an electric motor. The module can be used in association with a microcontroller for motor speed detection, pulse count, position limit, etc. In principle, any rate meter simply measures the rate at which some event occurs. Usually this is done by counting the events for a given period of time (integration interval) and then simply simply dividi dividing ng the number of events by the time t ime to get the rate.
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Basically, the microcontroller-compatible motor speed sensor module described is a simple device that yields processed pulse trains when the visual path of its optical sensor is physically interrupted by some sort of slotted wheel or similar mechanism (an optical sensor commonly consists of a light emitting diode that provides the illumination, and a phototransistor that senses the presence or absence of that illumination). The transmissive optical sensor used here consists of an infrared light emitting diode and a phototransistor. This both prevents interference from stray external light sources and by having the two components matched for a specic frequency of radiation, they are even more immune to undesired interference.
The Circuit As stated, the circuity can be used to send calibrated pulses to a microcontrollerbased tacho meter or similar circuit/device. The wiring of the hardware turned out to be deceptively simple. At the heart of the circuit is the OS25B10 transmissive optical sensor with phototransistor output (OC1). Next is the venerable LM393 dual comparator chip (IC1) congured as a simple Schmitt trigger (schmitt triggers are fundamental circuits with several uses; one is signal processing, they can pull digital data out of some extremely noisy environments). The green indicator (LED1) indicates the presence of voltage applied, and the red indicator (LED2) monitors output of the motor speed sensor module. Recommended working voltage of the module is 4.5 to 5.5 volt dc.
(http://www.electroschematics.com/wp-content/uploads/2015/09/motor-speed-sensormodule-circuit.png)
LM393 datasheet (http://www.electroschematics.com/7980/lm393-lm2903datasheet/)
Note that a 180R resistor (R1) is used here to limit operating current of the light emitting diode inside OS25B10 optical sensor (OC1). It might become necessary to alter this value in your prototype. Similarly, try to tweak the value of the 10K resistor (R2) to get a decent voltage swing based on your real life application. The last 10K resistor (R7) is an optional pull-up resistor.
The Encoder Disc Note that one side of the optical sensor holds s a light emitting diode, and a photo transistor on the other side. If the visual path is not blocked, phototransistor would conduct, but when something blocked the light falling on the photo transistor it wouldn’t conduct. So an encoder disc (with a proper encoder resolution) can be placed in the slot of the optical sensor to count rotation rate of a connected wheel/motor.
(http://www.electroschematics.com/wp-content/uploads/2015/09/encoder-discwheel.png)
The encoder disc (also known as index wheel) in the above image have multiple slots/holes. You can easily fabricate your own encoder disk from a sheet of stainless steel or hard plastic. If you are interested only in speed sensing (not position sensing) application , one set of slots is sucient for the task.
(http://www.electroschematics.com/wp-content/uploads/2015/09/encoder-disk.png)
Proof of Concept My basic prototype was built on a small piece of perfboard, photograph of which is shown below (some components are soldered at the bottom side of the perfboard; power indicator not wired).
(http://www.electroschematics.com/wp-content/uploads/2015/09/proof-concept.png)
After construction and pre-ight test, the module was connected to an Arduino board and measured the rotation per minute (rpm) rate of a geared robo motor (150rpm@5V) with the help of a home-made encoder disc (resolution 12 slots/disk) attached to its shaft. Final result observed was somewhat close to the spec of the robo motor’s rpm value. Arduino hardware hook up indicator (plus the demo sketch) is given below. Have a try!
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int encoder_pin = 2; // pulse output from the module unsigned int rpm; // rpm reading volatile byte pulses; // number of pulses unsigned long timeold; // number of pulses per revolution // based on your encoder disc unsigned int pulsesperturn = 12; void counter() { //Update count pulses++; } void setup() { Serial.begin(9600); pinMode(encoder_pin, INPUT); //Interrupt 0 is digital pin 2 //Triggers on Falling Edge (change from HIGH to LOW) attachInterrupt(0, counter, FALLING); // Initialize pulses = 0; rpm = 0; timeold = 0; } void loop() { if (millis() - timeold >= 1000) { //Don't process interrupts during calculations detachInterrupt(0); rpm = (60 * 1000 / pulsesperturn )/ (millis() - timeold)* pulses; timeold = millis(); pulses = 0; Serial.print("RPM = "); Serial.println(rpm,DEC); //Restart the interrupt processing attachInterrupt(0, counter, FALLING); } }
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14 Comments
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kikiloaw pulse means interruption for IR Sensor by blocking receiver and transmitter. right? its that what you mean in your code in variable “pulsesperturn”? Posted on December 05th 2015 | 4:38 pm (http://www.electroschematics.com/12275/motor-speed-sensormodule-circuit/#comment-1873474) Log in to Reply (http://www.electroschematics.com/wp-login.php? redirect_to=http%3A%2F%2Fwww.electroschematics.com%2F12275%2Fmotor-speed-sensor-modulecircuit%2F)
Taha Thank you again But can I know if I can connect it to LCD
Posted on November 27th 2015 | 2:49 pm (http://www.electroschematics.com/12275/motor-speed-sensormodule-circuit/#comment-1869362) Log in to Reply (http://www.electroschematics.com/wp-login.php? redirect_to=http%3A%2F%2Fwww.electroschematics.com%2F12275%2Fmotor-speed-sensor-modulecircuit%2F)
tkhareendran Yes, with little skill and patience you can add a display panel with the hardware.For this,try an LCD Keypad Shield and modify the code accordingly. To make it more clear,refer lcd-related projects published here from time to time. I regret,due to time constraints I am un able to re-write the code for specic requirements. Posted on November 27th 2015 | 3:04 pm (http://www.electroschematics.com/12275/motorspeed-sensor-module-circuit/#comment-1869371)
Taha My last question: How we’re gonna connect this circuit with the motor?And Is there’s a video for this circuit while it works? And Thank you again. Posted on October 20th 2015 | 5:38 pm (http://www.electroschematics.com/12275/motor-speed-sensormodule-circuit/#comment-1846053) Log in to Reply (http://www.electroschematics.com/wp-login.php? redirect_to=http%3A%2F%2Fwww.electroschematics.com%2F12275%2Fmotor-speed-sensor-modulecircuit%2F)
Dandara Tohundowc! That’s a really cool way of putting it! Posted on December 22nd 2015 | 12:10 pm (http://www.electroschematics.com/12275/motorspeed-sensor-module-circuit/#comment-1882948)
Taha Thank You very much. It was the last step.
Posted on October 22nd 2015 | 8:10 pm (http://www.electroschematics.com/12275/motor-speedsensor-module-circuit/#comment-1849264)
T.K.Hareendran (http://www.electroschematics.com/wp-
content/cache/comment-plus/1847051-1024x768.jpg?1472108799) @Taha: Welcome! Note that no electrical interfacing is required here. First of all, prepare a suitable index disc (see the article) for your specic application, and “optically-couple” the disc to the sensor module. Refer the example image! Posted on October 21st 2015 | 5:47 am (http://www.electroschematics.com/12275/motor-speedsensor-module-circuit/#comment-1847051)
tkhareendran @Taha: It’s well below 50 mA (actually it depends on the current rating of the IR module, and the output LED)! Posted on October 13th 2015 | 5:55 pm (http://www.electroschematics.com/12275/motor-speed-sensormodule-circuit/#comment-1833886) Log in to Reply (http://www.electroschematics.com/wp-login.php? redirect_to=http%3A%2F%2Fwww.electroschematics.com%2F12275%2Fmotor-speed-sensor-modulecircuit%2F)
Taha Thanks Posted on October 20th 2015 | 5:30 pm (http://www.electroschematics.com/12275/motor-speedsensor-module-circuit/#comment-1846046)
Taha Sorry but for complete it, I was asking how much power it’ll take for VCC ? Posted on October 13th 2015 | 5:45 pm (http://www.electroschematics.com/12275/motor-speed-sensor-modulecircuit/#comment-1833880) Log in to Reply (http://www.electroschematics.com/wp-login.php? redirect_to=http%3A%2F%2Fwww.electroschematics.com%2F12275%2Fmotor-speed-sensor-module-circuit%2F)
Taha I was searching for a project, And I found this one. When I read it I found it very good and simply project. Really, Thank You. Posted on October 13th 2015 | 5:41 pm (http://www.electroschematics.com/12275/motor-speed-sensormodule-circuit/#comment-1833874) Log in to Reply (http://www.electroschematics.com/wp-login.php? redirect_to=http%3A%2F%2Fwww.electroschematics.com%2F12275%2Fmotor-speed-sensor-modulecircuit%2F)
tkhareendran @Taha: Thanks! Posted on October 13th 2015 | 5:45 pm (http://www.electroschematics.com/12275/motor-speedsensor-module-circuit/#comment-1833879)
Mart I was thinking about how to make a drive by wire circuit control system to drive a mechanical device and this is a simple means of doing this. By mechanical device, I mean, for example, a portable mobile scaold that I can stand on and motorize it to move me around while standing on it without having to get down and move it myself. Or, building a small go-cart and electronically control the desired speed by using this speed control circuit system.
Obviously there are many other applications where speed control is desired and this simple circuit you describe could be easily implemented. I have an arduino uno and so thank you for providing the sketch and circuit diagram to achieving and implementing this system. Thank you very much for writing this article. Posted on September 23rd 2015 | 1:06 pm (http://www.electroschematics.com/12275/motor-speed-sensormodule-circuit/#comment-1810026) Log in to Reply (http://www.electroschematics.com/wp-login.php? redirect_to=http%3A%2F%2Fwww.electroschematics.com%2F12275%2Fmotor-speed-sensor-modulecircuit%2F)
T.K.Hareendran @Mart: Thanks for your keen interest in my article. Really happy to note your open feedback. Posted on September 23rd 2015 | 1:53 pm (http://www.electroschematics.com/12275/motorspeed-sensor-module-circuit/#comment-1810085)
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