Let's Make Robots!

Second set of eye's on a sn754410 driver setup

wired up

 

Note green LED(yes it's set up in the correct orientation and even when I hook up a vmeter I don't see a voltage) is not lit up.(red is power indicator) I feel like amature hour here with this simple circuit yet can't seem to get it to work. Tried 2 different chips. Recommendations are welcome...I only spent this morning looking at it....

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.
voodoobot's picture

Thanks for the help and suggestions guys...this just goes to show, pins that float down't know which way to go...headaches will ensue....

Chris the Carpenter's picture

Got it, you age getting your ground from the other output for your indicator led. However, I don't think I see the input (that controls that ground) connected to ground (pin 2)

 

voodoobot's picture

When not enabled it should be low, but correct, I'm not pulling it down. most of the suggestions have been to try this...so yeah...when I get home I'll tie it down with a 10k...

ChuckCrunch's picture

in the application info they use a 10k resistor to enable it but i don't think this makes much difference   . and i agree with TeleFox

voodoobot's picture

Yep, tried it this eve and that looks to have worked....next time....tie it down....

Chris the Carpenter's picture

You have a resistor coming out of pin 3 (output 1) then going to your led, then the led goes back to pin 6 which is the other output for that side. Also, your red jumper wire (with the nice ends on it) is plugged in and jumping + to input 2 for that side (pin 6) but your test led seems to be plugged into output 1 (pin 3). I think you have all of this correct --its your testing that needs a fix, my friend.

voodoobot's picture

Chris, Think of the LED and resistor as the motor setup it connects the High and Low of 1Y and 2Y with 2Y giving the V+ and 1Y low. When pin 1 is on(1/2 enable) I have 2A enabled as well. This gives me +v out of 2Y. 1A I'm leaving alone and this should put 1Y into the low state(but not high impedence). This should work....I'm not sure how my test needs a fix..

TeleFox's picture

Try pulling input 1A to ground, if nothing else that will eliminate one potential problem.

voodoobot's picture

Yep, that worked....wow I really should have tested this(slaps forehead)....thanks for reinforcing this....I should have known...

voodoobot's picture

Yep, I was considering that, though from some of the different configuration, it's not something often done. I'll try it though. I think I checked the voltgate coming out of the Xy using the ground ref instead of the Yy...but still nothing.