how do I connect a vibration motor to my espruino device? How long would it last?

[espruino-discuss3]

Posted at 2019-12-17 by BootySnorkeler

Hi there,
I want to make a small robot that moves with two vibration motors on each side. I will remove the motors' eccentric weights and replace them with small wheels, so the vibration motors will essentially act like really small DC motors. I'm thinking of using an MDBT42Q. How do I connect the motors to the microcontroller? Should I just connect one wire to a signal and another to ground? Or are there passive components needed?

Also, how long would my robot last? It will have two mini vibration motors, two green LEDs(on for about 5 minutes I think) and will be recieving commands OTA via bluetooth. It's all powered by a CR2032 battery.

Thanks!

[gfwilliams]

Posted at 2019-12-17 by @gfwilliams

I think realistically for vibration motors you'll need something to increase the power output. I'd suggest adding one FET (or transistor) per motor. This may help: http://www.espruino.com/mosfets

But basically:

• connect the FET 'source' to GND
• connect the vibration motor between VCC and the FET's 'drain'
• connect the FET's 'gate' to an Espruino IO pin

How long it lasts really depends on your motor, but with a CR2032 it won't be a long time. They hate large power draw, and running two motors are once might be too much.

You could however use a lithium ion battery with the MDBT42Q breakout (as it has a voltage regulator) and that'd be fine. You can get 'mini phone charger' things about the size of a keyring that have a lithium battery and charger and are dead cheap, so potentially that could be an option.

Either that or you can buy LI2032 (lithium ion CR2032-size cells) that'd work great

[espruino-discuss3]

Posted at 2019-12-17 by BootySnorkeler

Can I power the MDBT42Q module(not the breakout board) with a 3.7v lipo and a voltage regulator? I also edited my original post and added some more info on how the motors will be used, so just a heads-up.

Thanks!

EDIT: will I need any passive components for the mosfets?

[espruino-discuss3]

Posted at 2019-12-17 by maze1980

I'd say even two motors with 10mA are too much and will drain a CR2032 battery really fast. I'd add a capacitor and a diode in parallel to each motor (over voltage/inverse voltage protection).

However I'd check the motors first, do they have the right speed and power at the planned voltage, or do you need more power/a higher voltage and gears...

[espruino-discuss3]

Posted at 2019-12-17 by @allObjects

I cannot see a direct drive work... you need some gears... these motors run at / up to 10k RPM... and even with a very small wheel you end up with very high power draw to get moving but quickly you are way too fast... even when driving w PWM.

Instead of vibration motor think of 2 free running nano servos... PWM driven.

[gfwilliams]

Posted at 2020-01-07 by @gfwilliams

Instead of vibration motor think of 2 free running nano servos

I think @barry_b_benson intends to make a 'bristlebot'?