Hi to all, my name is Cosimo and I need help about stepper driver.
From an old printer I’ve get a bipolar stepper and now I’m trying to drive it with L298 and L297 configuration. Whitout the stepper the outputs of L298 are: 0V 12V 0V 12V. It’s ok! But with the motor connected the outputs of L298 are: 6V 6V 6V 6V. Why this?
Thanks in advance.
Cosimo
Testing the L297 output I’ve without the motor: pin 4 0V, pin 6 4.4V, pin 5 4.4V, pin 7 0V, pin 9 4.4V, pin 8 4.4V.
Testing the L297 output I’ve with the motor: pin 4 0V, pin 6 4.4V, pin 5 2.2V, pin 7 0V, pin 9 4.4V, pin 8 2.2V.
What is the resistance of the stepper motor windings?
The stepper may require too much current for the L298 driver, in which case you should use something like the A4988 motor driver from Pololu.
The motor resistance windings are 3.9 ohm… The stepper buzz with 250mA so I’ve set to 100mA to don’t hear buzz…
At 12V, those motors will draw 3 amperes/winding. That is far too much current for the L298 H-bridge, so it overheats and shuts down. You can use the DRV8825 driver if you set the current limit to 1.5 ampere or less. http://www.pololu.com/product/2133
Alternatively if lower motor power is an option, you could put a ~6 ohm, 10 watt resistor in series with each winding and then use the L297/L298 combination. That will reduce the winding current to an acceptable value, but the resistor will get quite hot, as well as waste power.
I use a Rsense (1 ohm 2W) and set Vref to 0.1V for 100mA…
The L297/L298 is very old technology. You will have much better luck with a modern MOSFET motor driver, like the ones suggested.
can I use tip122?
solved! 6V are normal in stepper when the start condition is 0101 with 12V supply of stepper… the problem was ground connection between boards (driver L297+L298 and PIC32 starter kit) and clock speed to high… thanks to all.