5 years, 5 months ago.

LPC11U24 often reboot suddenly

I am making a simple self-balancing robot with LPC11U24 now. So I connect the device with motor driver IC which is connected to the motor. Although the device work well when I don't use the motor , it will often reboot when I use it with motor. I am not sure but ,it seems to me that when the large current is flowing the motor,the phenomena occur. But I separate the power of mbed from power of motor. So mbed is only sending PWM signals to motor driver IC.

It is mystery to me! Please tell me why such a problem happens !

Can you specify what is exactly connected and how you power every part? That is indeed a pretty standard occurance when using motors due to power supply issues, but if they are completely seperated it should not happen.

posted by Erik - 08 Feb 2015

The motor and the mbed of course share the grand(0V). And mbed 's p5 and p6 terminals are connecting with motor driver IC in order to send PWM signal. The mbed is powered by USB cable from my PC,and motor is powered by a battery.

posted by Hirokazu Ishida 08 Feb 2015

1 Answer

5 years, 5 months ago.

Seems like electrical noise. When driving a motor, the changes in current in the commutator will induce a reverse polarity spike on the motor terminals. These can be quite large, in the hundreds of volts, if they're not suppressed. You can do that by either terminating each terminal to the housing of the motor with 100nF and one across the terminals.

Hope this helps.

Accepted Answer

Thanks a lot. I tried it and mysterious phenomena seemed to be disappeared. but,there is one worry thing.I did it with 10nF condensers because I don't have 100nF ones. Is this OK?

posted by Hirokazu Ishida 08 Feb 2015