motor/h-bridge issues

Other Hardware Motors, Mechanics, Power and CNC
1

Hello all,

I'm trying to use an H-bridge (SN754410: HTTP 301 This page has been moved) to drive this DC motor I have. I wired it pretty much exactly the same way they did here, except the only difference is that I connected the EN pin to 9 on the Arduino and pins 1A and 2A to 4 and 5 on the Arduino (and I checked the wiring over and over and over again, so I know it can't be a problem with that): http://web.ics.purdue.edu/~fwinkler/616/sn754410_Arduino.pdf
For reference, I've also attached my code to this message.

For some reason, it doesn't seem to be working at all. I tried using a 9v battery instead, but it still didn't work, and I don't think that's the problem anyway because the motor works fine when I simply plug it into the rails of the breadboard (while it's connected to 5v).

I've been trying to figure this out all day but to no avail. Any help?

2

Sorry, didn't see any code attached.

Do you have a multimeter (DMM)? Can you verify the signals on the SN754410 are what they should be according to the datasheet?

It might help to start with a blank sheet of paper and trace out the wiring you have on your breadboard (without peeking at the Winkler tutorial). Then compare your wiring with the one you're trying to match and make sure you haven't missed anything, or wired something improperly.

--
The Quick Shield: breakout all 28 pins to quick-connect terminals

3

I've also attached my code to this message.

Where?

First thing to do is to disconnect the arduino and just wire pins 1, 2 and 7 of the SN754410 to the appropriate logic levels, that's ground or +5V. If the motor then works you problem is with the software, if not it is the hardware.

I checked the wiring over and over and over again, so I know it can't be a problem with that

You will be surprised how many times you can "check" the same mistake.

4

Grumpy_Mike:
You will be surprised how many times you can "check" the same mistake.

Quote of the day!

:smiley:

5

Sorry, here's the code.

PurdueDCMotorControl.pde (1.01 KB)

6

this DC motor I have.

What voltage and current does the motor need??

7

Try putting a fat delay(10000); at the end of the loop.

Have you done the tests I said with the hardware pins, what were the results?

8

Thanks for all your help, guys. I did some debugging with a friend and we ultimately concluded that the breadboard was acting wonky. We transferred all the wires and the H-bridge to a new breadboard and now it's doing just fine!

One question though—the H-bridge chip does heat up when the board is connected to power. Nothing too drastic, but it's noticeably warmer than chips connected to power often tend to be. Could this be a bad sign?

9

If that is when a motor is running then it is normal, the chip is dissipating some energy when it is passing current and that's why it feels warm.