L293D Motor driver
This chip enables you to take 4 outputs and turn them into 2 that can be reversed.
Note that the chip can get quite warm, but it is designed for that.
Benefits:
You can control 2 motors in both directions instead of 4 in only one direction.
Disadvantages:
There is a 1.5V voltage drop within the L293D driver chip.
If you run both motors and servos on the same circuit, your servos will allways get 1.5V more than the motors - and typically you would want it the other way around!
H-bridges...
Everyone's got a favorite chip, but have a look at the SN754410. http://focus.ti.com/docs/prod/folders/print/sn754410.html.
The L293 has 1A drive, but no clamping diodes while the L293D has 600mA drive with clamping diodes. The SN gets you both 1A and diodes, and they're a tad cheaper at Digikey or Mouser (in the US at least). And they're otherwise pin-compatible, so you don't even have to change your designs.
I think the manual indicates
I think the manual indicates that diodes inside the SN754410 are for ESD protection not for kickback protection by the motor's inductance. Use it for kickback protection is not gauranteed.
Regards,
-Pandit
Wow, interesting!
"And they're otherwise pin-compatible, so you don't even have to change your designs."
Wow, thanks, Elliot, that is very, very interesting for us who tend to use standard boards. Thank you very much!
/ Frits
.
I'm going to wire up my
I'm going to wire up my motor driver (on a breadboard of course I want to learn which pins do what) and I have a couple questions. According to the datasheet (http://www.rev-ed.co.uk/docs/L293D.pdf) it looks like I know the following pins:
Is the above true? If so what is Pin 1 (Enable 1) and Pin 16 (VSS Logic Supply Voltage)
I know it would be easier to use the project board, but I'm an overachiever ;) I want to understand things more than I need to. Once I figure it out I'll document it so I won't have to ask again.
As usual I figured it out
As usual I figured it out after I posted. I looked at the datasheet for the 28x project board and it had specs for the motor driver. http://www.rev-ed.co.uk/docs/AXE020.pdf
Bottom of page 4 shows the pins for the motor driver.