> On Wednesday 24 June 2020 14:48:09 andrew beck wrote: > > > All it says is they use pwm for controlling via x72 x80 x82 etc. > > > > I forgot to what most buy as you say it doesn't matter really. > > > > I am more interested in how pwm works. > > > > As far as I know there is a voltage and duty cycle and a dir. But I > > haven't used it before. > > Three wires, two signals, against ground or logic zero. Its common if > driving a motor driver, to use the 5 volt line as the common, and logic > zero is the on state because the transistors in the average breakout > board can pull low much better than the can push high. The diff can be > 10/1. > > One is direction, commonly a logic zero means backwards > > The other signal can be of any time duration but should be fast enough so > as an averaging circuit won't have too much ripple in it. The percentage > of that time it spends at a logic one, from 1% to 99% represents the > requested speed, if it spends 25% of its time at a logic one, that > represents a request for 25% of full speed. Etc, etc.
Then used for signaling there is another method. Instead of averaging voltage time of flanks is measured, exacte voltage amplitude is not important, some voltage noise will not effect signal or have very limited effect on flank, pulse width could usually be measured accurately even with a cheap Micro controller using one of the internal timers. Then using this signal you do not need to read about inverters tough some knowledge about electric motors might be useful for the understanding dynamic response even though signal is a simple speed signal. Nicklas Karlsson _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
