Well if U7 is not active (which I think you are right - going thru the truth table of the logic feeding it now) how do you expect DO0 to change? The is where the signal is coming from. That may be the crux of the problem?
Dave On Monday, June 9, 2014 12:01:25 PM UTC-5, David Fry wrote: > > Dave, > > have a quick look at gates U6C, U6D & U11F > U7 will not be active for port address 034H > > Thomas, > > out of interest what CPU card are you using ? > > regards > > David Fry > > On Monday, June 9, 2014 5:45:01 PM UTC+1, yoda wrote: > >> John >> >> I will say it again - the type of CF card can have no effect on this >> circuit. Why is DO0 run through the 7407 anyways - it is already buffered >> at the 244 U7? I think there is so much delay introduced in the circuit >> that DO0 is never really stable when it is clocked into the 7474. I think >> it is a race situation and you are lucky if it can ever be deterministic. >> I guess one thing that might be tried is to eliminate the 7407 by bending >> out pin 2 of U16 and connecting it to pin 18 of U7? Don't know if that >> is going to help or not. Thomas can you put logic analyzer on pin 2 and 3 >> of U16 so we can see the timing relation between the 2 signals - that will >> tell what is being clocked in. >> >> Dave >> >> On Monday, June 9, 2014 11:19:35 AM UTC-5, monahanz wrote: >>> >>> Sorry I meant actual CF card itself, Kingston, etc.. >>> >>> John >>> >>> >>> >>> >>> >>> *From:* [email protected] [mailto:[email protected]] *On >>> Behalf Of *Thomas Owen >>> *Sent:* Monday, June 9, 2014 9:16 AM >>> *To:* [email protected] >>> *Subject:* [N8VEM-S100:4063] Re: CF IDE card checkout and final >>> assembly problem >>> >>> >>> >>> John, >>> >>> It is the newest batch I believe, '02a'. >>> >>> Thanks >>> >>> On Sunday, June 8, 2014 7:58:45 PM UTC-4, Thomas Owen wrote: >>> >>> All, >>> I had posted this to the thread dealing with ordering this card, but >>> decided to post a new topic dealing with the problem I have had with final >>> checkout of the board. >>> >>> During assembly the board passed all the 'in progress' checks. The >>> final steps were to output to different ports: >>> >>> >>> I have output the following and everything passes: >>> >>> QO33,80 ; Configures ports A, B and C as output ports >>> QO32,2B ; Selects right hand pair of digits >>> QO30,01; display 01on right digit pair and work through each bit - all ok >>> >>> QO32,2c; Selects middle pair of digits >>> QO30,01; Should display 01 on middle digit pair, work through each bit - >>> all ok >>> >>> QO32,2d; Selects left hand pair of digits >>> QO31,01; Should display 01 on left digit pair, work through each bit - >>> all ok >>> >>> All displays are correct. >>> >>> Now the final step is the Drive Select and that is where I am having >>> trouble: >>> >>> Board always comes up with 'Drive A' selected >>> >>> Now, QO34,0; no change >>> >>> Reset, start again: >>> >>> QO34,1; no change >>> >>> I can never select drive B. >>> >>> Several generous members (thank you David Fry) have made suggestions, >>> and here is where I now stand: >>> >>> My preliminary check this afternoon shows me that there is a timing >>> issue at U15, the 74ls02. Using my logic analyzer and monitoring the >>> inputs and the output (which clocks the drive select flip flop) I see a big >>> timing difference between SEL_SECOND and WR. >>> >>> What this means is that the output of the gate never goes high allowing >>> the bit change to effect drive change/selection. >>> >>> I am going to get some screen shots from the analyzer tomorrow, and if >>> anyone has any suggestions I would greatly appreciate it. >>> >>> Thanks, >>> Thomas >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "N8VEM-S100" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> For more options, visit https://groups.google.com/d/optout. >>> >> -- You received this message because you are subscribed to the Google Groups "N8VEM-S100" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
