DPRG mailing list archives: [DPRG] Motor backlash / Back EMF

Sun Jan 6 00:25:25 CST 2008

Put a 1 - 10uH inductor between the logic ground and the system 
ground. I'm sure the LM293D is compensating for the spike from 
turning off the motor but I suspect it can do nothing to prevent 
"ground bounce" where the inductance of the motor wiring to the 
battery causes a DC bias to appear on the ground plane. This "lifts" 
the ground plane high enough so that the difference between the 
ground the ATMEL sees and its Vdd line kicks in the brown out 
circuit. The inductor will impede that bounce from affecting the 
microcontroller.

--Chuck

At 08:34 PM 1/5/2008, scott at lighthouse21.com wrote:
>The Power Wheels turned robot Redcar made it to the end of the block and
>back on its own power earlier this evening (being driven via a Play
>Station controller).
>
>However, whenever the steering motor makes an
>adjustment the Atmel resets as soon as the motor shuts off.  The logic and
>motors have separate batteries and the Atmel drives the motor via relays
>controlled by an L293D.   Any methods for isolation?  Eric has recommended
>a full motor controller but I'm hoping to avoid that if at all possible.
>Contact me at scottinthebooth at gmail.com and I'll send a wiring diagram but
>its too big to attach to the list.
>
>Scott
>
>
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