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Author Topic: L298N Motor Driver board  (Read 924 times)
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Hi Guys

I'm using a L298N Motor Drive board in a parallel configuration to drive a 12V motor; the Arduino I'm using is a Mega 1280.



The motor only needs to run in one direction so the direction Pins are always set to these values:

INA HIGH
INB LOW
INC HIGH
IND LOW

The terminals on the motor are wired to INA and INC or INB and IND

The speed of the motor is controlled using a PWM on the ENA and ENB Pins.

The problem:

I have two of these boards, one works the other does not. I have double and triple checked all the connections and the outputs being set in the code which increments the PWM from 0 to 255 in steps of 2. I have also swapped the connections from the Arduino to the working board to the non-working board but still no response. After this I also put the connections from the Arduino to the non-working board onto the working board and it worked! Thus there must be something wrong with the board itself. I'm on a tight schedule as this is for a uni project so ordering another board from China which takes 2-3 weeks to arrive is not really an option.

Any suggestions of what could be wrong/ what I can do to rectify the problem would be much appreciated. Thanks.
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Check what voltages are getting where on the board with a multimeter - there might be a split trace or dry joint
(something that's fixable), but you need to narrow down the possibilities.  It may be the L298 is blown, it may be
a knock-off L298 (quality control reject) if its a cheap board from China on eBay.
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Maybe you could get your hands on a loose 298 chip and just make up a new driver?- the 298 apparently doesn't fit nicely into breadboard (never tried it myself) so you might have to kludge a bit by bending the connectors, or use soldered wires. On the other hand the 293 provides similar (but not identical) capability and it's a dip16 which fits in a breadboard which makes things much simpler.

Here's an example of using a 293D on a breadboard. Edit: Caution! The 293 pins on the sketch are not drawn to match the pins on the chip- they're drawn to make the drawing neater.

Check the datasheets for the differences... max current is one that I know of, so you'll need to see if the 293 is ok for your motors. 293D has flyback diodes built in.

« Last Edit: March 10, 2013, 01:19:58 am by JimboZA » Logged

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i have a similar board with L298N try to find out or your resistor capacitor diode are ok with a multimeter probably the diodes are damage
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Thanks for getting back so quickly guys.

MarkT: I have now gone over the board and can't find any split traces or dry joints.

JimboZA: I am looking into your suggestions. Thanks.

THX_RoG: All the discrete components seem to be working. Especially the diodes.

When the outputs are set to high, with a nominal 12V battery supply on VCC, only ~1.4V is seen at the terminals to the motors. I assume the chip is a dud or has been blown. Going to get a new L298N chip and swap it out, if this doesn't work I'll build my own motor driver.

Thanks again.
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Surely somewhere UK will have a board?- maybe not the identical brand, but similar 298 based one? I don't know what HM's Royal Mail is like nowadays, but someone should be able to get a board to you overnight...
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Look here http://electronicsclub.info/ for basic electronics

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