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Electronics => Electronics => Topic started by: m_M321 on March 21, 2013, 10:46:31 AM

Title: L293D
Post by: m_M321 on March 21, 2013, 10:46:31 AM

I am using the 'Circuit Diagram' on the website:

http://www.electrosome.com/dc-motor-l293d-pic-microcontroller/ (http://www.electrosome.com/dc-motor-l293d-pic-microcontroller/)

The problem is when I connect the ground of the Motor Supply battery the LED for my 5v supply comes on even though that switch is off.

Title: Re: L293D
Post by: jwatte on March 21, 2013, 11:13:10 AM

The circuit diagram with the microcontroller?
Are you using a pull-down resistor on the motor controller inputs, to make sure there's not a weak pull-up enabling it?

Title: Re: L293D
Post by: m_M321 on March 21, 2013, 04:57:40 PM

thank you for your reply.

yes, the diagram towards the bottom of page w/ micro controller.

I tried 10k pull down resistors on the inputs of the L293(pins 2 & 7) with no change in the results.

Title: Re: L293D
Post by: Azraels on March 21, 2013, 10:17:43 PM

According to the datasheet found here: http://www.alldatasheet.com/datasheet-pdf/pdf/27189/TI/L293D.html (http://www.alldatasheet.com/datasheet-pdf/pdf/27189/TI/L293D.html)
you should have 1 10k resistor going from the 5V logic supply to pins 1 and 9. In your case probably just 1 if you are using one motor.
Also you could pull the other enable to ground if your not using it.

Title: Re: L293D
Post by: m_M321 on March 22, 2013, 09:13:36 AM

Thanks for the reply.

After attempting to applying responses with no change I swapped the L293 out and guess what....no more problem!