Flying Electron wrote: > > Looking at the Pico Systems PWM Brushless Servo Amplifier, it recommends > a PWM frequency of at least 25khz, so assuming the parallel port could > be driven fast enough the CPU would have to send data to the parallel > port at least 50000 times a second to toggle a pin as opposed to sending > 1000 commands a second to vary the generated PWM duty cycle. Is that > kind of how it works? > > No, not at all. Either using the Mesa board or the Pico Systems PWM controller board, the CPU sends a PWM width command once every millisecond, and the PWM generator sends the required pulse width (with much greater accuracy and resolution) to the drive. The later Pico Systems PWM controllers set pulse width in 25 ns increments, so at 50 KHz frequency you get 1 part in 800 resolution or 0.125 %.
You could possibly get about 10 us resolution from the parallel port directly, at 50 KHz that would give you a resolution of 50% which would never work for a servo drive. Jon ------------------------------------------------------------------------------ This SF.Net email is sponsored by the Verizon Developer Community Take advantage of Verizon's best-in-class app development support A streamlined, 14 day to market process makes app distribution fast and easy Join now and get one step closer to millions of Verizon customers http://p.sf.net/sfu/verizon-dev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
