Never mind DO0 comes directly off the bus. Dave
On Monday, June 9, 2014 12:18:25 PM UTC-5, yoda wrote: > > 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.
