Great Jeff. Thanks for the explanation. Why is a signal name required?
For instance: Why doesn't this work: net outputpin inputpin From what I understand this is required: net signalname outputpin inputpin From what I have seen, if a signalname does not exist that can be used, one must be created first before the net command will function. Thanks, Dave Jeff Epler wrote: > On Mon, Oct 19, 2009 at 09:17:30AM -0400, Dave wrote: > >> Are the direction arrows actually used by the Net command? IE => <= >> <=> etc? >> >> I thought that I had read that they do not matter but are simply for >> human clarification.. >> > > That's correct. You can remove the arrows from a net or linkXX command > and it has exactly the same effect. > > >> I also don't understand the format where a signal name has to be placed >> after the Net command even though it seems to be irrelevant oftentimes. >> > > The net command needs a signal name plus at least one pin name. > > If you're familiar with linkxx, then you should understand that > net s p q r > is equivalent to > newsig s hal-type-of-pin-p > linksp s p > linksp s q > linksp s r > > >> But if you have two read/write pins how do you know which way the >> read/write is going? >> > > By enforcing the rule for the number of writers. > > Each signal may be linked to any number of readers. (Hal pins with > direction "IN") > > A signal may be linked to 0 or 1 writers (hal pins with direction "OUT"). > > If there is no writer, then a signal may be linked to any number of > bidirectional pins (hal pins with direction "I/O"). > > Because of the second rule (the at-most-one-writer rule), you know the > direction the information is flowing: from the single writer to all of > the readers. (the writer is free to read the value from the pin as well, > but there's little point to it) > > The third rule is for a few special-purpose pins; the only one of note > is index-enable. It allows a "one line handshake". Suppose that > component C wants to request an action from component D, and be notified > when the action is complete. You can do this by having an I/O pin in > both C and D, and linking them together on a signal. > > When C wants to request the action, it sets the pin value from 0 to 1. > When D sees the pin value change from 0 to 1, it begins the action. > > When D completes the action, it sets the pin value from 1 to 0. > When C sees the pin value change from 1 to 0, it knows the action is > complete. > > Jeff > > ------------------------------------------------------------------------------ > Come build with us! The BlackBerry(R) Developer Conference in SF, CA > is the only developer event you need to attend this year. Jumpstart your > developing skills, take BlackBerry mobile applications to market and stay > ahead of the curve. Join us from November 9 - 12, 2009. Register now! > http://p.sf.net/sfu/devconference > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > > ------------------------------------------------------------------------------ Come build with us! The BlackBerry(R) Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9 - 12, 2009. Register now! http://p.sf.net/sfu/devconference _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
