Driving a Servo Motor with the BBC micro:bit

[@ra8620]

If you place French signal inside a Chinese processor it will compile into English.

[@freaker126]

cool. i love the micro bit. so small and simple but can run servo!

[@DownhillAllTheWay]

Is there a way of sensing when a servo has reached its target angle? I know I can use a pause to give it enough time to get there, but that will always be too short or too long (there's almost a 0% chance of getting it exact). It would be nice to be able to get on with whatever you want to do when it reaches that angle, rather than wasting time.

[@ElektorTV]

The only way to do that is to add a sensor (e.g. a mechanical or optical switch or a perforated disk or a potentiometer) to measure the sensor angle and give feedback.

[@DownhillAllTheWay]

@@ElektorTV Thanks for the reply. It's what I expected, though I had hoped that there was some little-known feedback from a typical servo that would do it. After all, they have a potentiometer in them and a microcontroller, so they have the 'smarts', though they would need a four-wire connection if they were going to transmit.

[@ElektorTV]

@@DownhillAllTheWay Servos are often quite easy to modify, so you might try to bring out that fourth wire yourself.

[@liviosemeraro2951]

Hey, amazing video a big thank's to you, but I have a question, what is the pin0.set_analog_period(value) ? ^^ happy coding !

[@ElektorTV]

Set the period of the PWM signal being output on pin0 to period in milliseconds. The minimum valid value is 1ms.

[@liviosemeraro2951]

@@ElektorTV It's used for ? And thank you for you answer ^^

[@ElektorTV]

@@liviosemeraro2951 The typical RC servo expects to see a pulse every 20 ms, which is why the PWM signal is set to a period of 20 ms. pin0.write_analog controls the width of the PWM pulse, which determines how far the servo will turn.

[@ianhydes5805]

the title is a bit misleading, you're controlling a servo not a stepper motor

[@ElektorTV]

You're right Ian, thank you for pointing this out to me.

[@ianhydes5805]

no problem. I didn't watch the whole video, just flicked through but it looked good for servo information. I'm just frustrated that I'm struggling to find much information on driving stepper motors or external interrupts for the micro bit. I'll get there I'm sure. Have fun, its neat technology

[@infinitystem6565]

Thank you mon ami!

[@csi228]

bonjour