Newbie- L297

[reuven81]

I wired only L297 but it didn't worked well....

As you can see in the pic. i wired the outpins 4,6,7 and 9 to led than to ground. Only the second and the fourth one worked than i send pulse ( i connect the pin 18 to 5 volt ) than they went off.

Sync , home , inh1 and inh2 to nothing

Gnd to ground

Sens1 and sens2 to ground by resistor ( 0,5 ohm )

A , B , C and D to the ground by leds

Enable , control , Vs , CW/CCW , Half/Full and reset to 5volt

Vref to 3 volts

OSC as in the datasheet
Please help!!!!

[doorknob]

I do not have direct experience using the L297 and L298, so this is just a guess.

It appears that you are expecting to see static levels on the A, B, C, and D outputs (to drive the LEDs).

My interpretation of the datasheet is that rather than static levels on those pins, the L297 is designed to give a chopped current on those pins. The value of the chopped current depends on the current flowing through the sense resistors.

Right now, you do not have any current flowing through those resistors.

So, maybe what you need to do is simulate having motor winding currents going through those resistors. Maybe you can do that by choosing a suitable resistor value (that will draw an appropriate current - they may need to be power resistors capable of dissapating some wattage) and connect each of those power resistors from perhaps a 12-volt or 24-volt power supply, to the respective sense resistor pins, so that the sense resistors can sense a proper amount of current (the L297 is probably measuring the voltage drop across the sense resistors as the current flows through them). To figure out appropriate values, you might want to look at the datasheet for the L298 and figure out what the circuitry looks like inside it - it is probably an H bridge or similar, and it will have ratings for the current and voltage that it is designed to handle.

But again, since I have not actually worked with those parts, I could be interpreting the datasheet incorrectly.

Also, what are you using to generate your clock pulse? If you are just touching the wire from pin 18 to +5V, then you may have a lot of contact bounce. So if you don't already have one, you might want to put together a simple pulse generator to hook up to pin 18.

For example, there is a simple pulse generator shown here:

http://www.geckodrive.com/ark-2/support.html