Please title this page. (states.htm)

Busy /Ack Time

State	Action	bat	baT	bAt	bAT	Bat	BaT	BAt	BAT
1	Get next byte of data T=0.5us Release /Strobe, Assert Data	1	5	1a	2b	1	6	4
2	T=0.5us, Assert /Strobe, Assert Data	2	1	2c	6	5		3d	3
3	T=0.5us, Release /Strobe, Assert Data	5		3	4	3	4	3e	4f
4	T=10s, Release /Strobe and Data	5i		4h	1	5		4g	6
5	T=5ms, Release /Strobe and Data	5j	6	1k		5	5	4

a: bAt - Printer not Busy, has released /Ack, we assert data without /Strobe and wait .5us
- bat - Printer not busy but seems to be asserting /Ack, we keep data live and wait for a bit to let the printer catch up and allow for transient /Ack.
- baT - Printer still not busy but /Ack persisted. We go to wait for /Ack to clear and may skip a data byte? Was this an /Ack that we thought had ended but was just bouncing? Mabey 6 is a better entry.
- Bat - Printer busy and asserting /Ack, shouldn't we be at a 5? but if we are at 1, then we just started or we were at 5 and not busy while /Ack ended and has now restarted with Busy on again or at 4 after a long time of not busy and no /Ack and now the /Ack we were waiting for comes with a Busy?
- BaT - the Bat was not a transient so something is wrong.
- BAt - printer is busy, go to 4 to wait for a while. If printer is offline, we will probably time out. If printer goes online, we will get an /Ack and think that we have sent a byte. How do PC routines prevent data loss under this condition?
b: bAT - We have been waiting .5us, now its time to:
c: bAt - Printer still not Busy, /Ack released, we keep data on and assert /Strobe
- bat - why are we getting an /Ack? Wait to see if its a transient
- baT - the ack persisted, mabey the printer is just that fast.
- bAT - Timeout while expecting a busy in response to our /Strobe. Mabey this should be a 2 instead to just hold untill busy comes up or a 3 to just continue anyway
- Bat - why are we getting an /Ack and while Busy? Just wait for the ack to end.
d: BAt - We have a Busy from the printer in response to our /Strobe. Do we need to wait anyway? If so make this a 2 and move to 3 when BAT.
e: BAt - We can release /Strobe since the printer responded to it and just need to keep the data on for another .5us.
- bat - 5
- baT - 5
- bAt - 3
- bAT - 4
- Bat - 3
- BaT - 4
f: BAT - Data was kept up for .5us, now we can:
g: BAt - Release the data and wait for a long while to let the printer work.
h: bAt - The printer is finished working on the data, but has not yet acknowledged reciept
- bat
- baT
- bAT
- BAT
i: bat - The printer is asserting /Ack
j: bat - We believe we have sent a byte to the printer. Now we just wait for the /Ack to release
- baT
- Bat
- BaT
- BAt
- BAT
k: bAt - The /Ack is over, we can repeate the process.

	1	2	3	3	4	4	5
Busy	_	_	~	~	~	_	_
/Ack	~	~	~	~	~	~	_
/Strobe	~	_	_	~	~	~	~
Data	D	D	D	-	-	-	-

file: /Techref/io/parallel/states.htm, 6KB, , updated: 2008/3/18 09:57, local time: 2024/11/22 12:01,

^{3.145.10.80:LOG IN}

©2024 These pages are served without commercial sponsorship. (No popup ads, etc...).Bandwidth abuse increases hosting cost forcing sponsorship or shutdown. This server aggressively defends against automated copying for any reason including offline viewing, duplication, etc... Please respect this requirement and DO NOT RIP THIS SITE. Questions?

Please DO link to this page! Digg it! / MAKE!

<A HREF="http://techref.massmind.org/Techref/io/parallel/states.htm"> io parallel states</A>

Did you find what you needed?

Welcome to massmind.org!

Welcome to techref.massmind.org!