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Avoiding fried mbed when controlling motors

Topic last updated 22 Jan 2012, by Wim Huiskamp. 1 reply
Jeremy Bennett
22 Jan 2012

I've managed to fry two mbeds when using them to control motors using an L293D H-bridge. In both cases trying to demonstrate to my children how you could use a microcontroller to control a simple motor.

I don't know how I did the first time. The second time, I misread the pin-out on the L293D and connected the 9V external power to Vcc1 (logic voltage) instead of Vcc2 (motor power).

It seems that simple use of an H-bridge is not viable for teaching teenage children about microcontrollers controlling motors. What is a safer way of using mbed to control motors, with a minimal risk of frying the mbed if you make a mistake?

Advice much appreciated.

Jeremy

Wim Huiskamp
22 Jan 2012

You could use opto couplers to completely isolate and protect the mbed I/Os from the L293. Alternatively, maybe a product like http://www.sparkfun.com/products/9571 is a good way to protect your mbed.