Hi,
Tutorial: http://www.societyofrobots.com/member_tutorials/node/120
Just to point you towards a bit on the L297, in your stepper tutorial, that needs correction:
When we ask the L297 to perform another step then: it applies voltage to the coils and as the current increases then so does the sensed voltage. This is compared against a reference voltage on pin 15. As soon as the sense voltage exceeds this reference voltage then the voltage is removed from the coils until we ask for another step. So the reference voltage on pin 15 (maximum of 2.5v) controls the maximum current supplied to the motors and should be just enough to make the motor 'step' - at which point the current consumption is turned off. Its a closed loop feedback system!!
It is a closed loop system for sure, but it doesn't work as a simple current turn off.
When the current level triggers the "over current sense", the L297 goes into Chopper/PWM mode and adjust the current to the maximum allowed (By V
ref). It does so by modulating either the phase lines or the inhibit lines, depending on the logic level on Control (pin 11).
