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Messages - J1mbo

34
Project development, ideas, and suggestions / Re: XT-IDE adapter with CPLD builds
Hi Sleepwalker et al, about these caps.  Is there a downside to 1uF X5R 0603s throughout (or even larger, 2.2uF maybe), instead of the 0.1uF on the power pins?  I'm just thinking that because these tend to be sold with 50 min quantity so it could reduce waste when assembling the board if they were all the same.

Many thanks!
36
Project development, ideas, and suggestions / Re: XT-IDE adapter with CPLD builds
Thanks, that would be great.

Can I just ask (and again, please accept my apologies for yet another noob question), but what is the purpose of the 47uF electrolytic on this board?  Value seems high compared to the stated Vin values on regulator datasheets for example.  If flash, CPLD and CF-socket all have 1uF or more close to each, I'm just wondering if the big cap is really needed at all.

Many thanks!
38
Project development, ideas, and suggestions / Re: XT-IDE adapter with CPLD builds
Re IBM ISA; very good!

Re compact flash, I could do with some help with CF host requirements for true-IDE mode; every guide I find has something different.  Specifically,

- 10k PU needed on /CD1?
- Any connection needed to /VS1, /INPACK, IORDY, /RESET?

If running the CF card at 3V3, presumably it would be bad to present /RESET from the host?

Many thanks!
41
Project development, ideas, and suggestions / Re: XT-IDE adapter with CPLD builds
Thanks.  Re testing, I don't know what it means yet.  That board will be circulated around a number of testers in the coming weeks, so things should become clearer once I've assembled a table of drives and compatibility.  In that sample of old drives, half of them worked and all of them were identified by the BIOS.
42
Project development, ideas, and suggestions / Re: XT-IDE adapter with CPLD builds
Many thanks, this is very helpful.  So far I've just been choosing parts from the price ascending view on Farnell.  Re noise, I was more concerned about noise into the CPLD, raher than back into the PC but presumably it makes no odds anyway.

** UPDATE ON DPv2 BOARD COMPATIBILITY **

From vc-forum member Stone.... here's what I've found so far. I verifyied the 850 mb drive and it still works fine but not with the IDE/XT card. Neither does a 1 Gig drive or a Seagate 80 mb drive. What does work is a 250, a 340 and a 420 -- all WD drives. The two drives that didn't work (other than the Seagate 80) were also WD. Even though the card can id them it can't read them as fdisk comes up empty with each one. But they all work (in another environment)
43
Project development, ideas, and suggestions / Re: XT-IDE adapter with CPLD builds
Really, I very much appreciate having such detailed input!  So I'll revert to the prior version.

For the regulator, the 1117's noise figure seems to be maybe 100 uV RMS where the MIC5205 quotes noise only a graph being about 1uV/root(Hz) in the same bandwidth.  I can't remember how to integrate that to get to uV RMS, but anyway, is the (presumably higher) noise on the 1117 likely to cause any issue (in a 25-year-old PC....)?

On the plus side, with that much 3.3V available I could add a 3-way header to select between 3.3V and 5V for supply to the CF card.  Re power measurement, all I've done is run it flat-out for an hour and see if VRM/CPLD we hot, which they weren't.  But that was at a data rate of only about 90KB/s.  With a combination of memory-mapped IO, older disks, and potentially much faster bus & CPU maybe its requirements would be quite different (although here I'm only looking at driving a CF card).

Many thanks!
44
Project development, ideas, and suggestions / Re: XT-IDE adapter with CPLD builds
Many thanks for taking the time to look through and provide this information!  Maybe TI 73033 200mA 3v3 regulator fits here - same package as the MIC5205 but with more juice.  I'm not totally sure I follow the bit about the unused address lines; so I've added R6, is that what you meant?

So, full change list:

- Replaced MIC5205 with TI73033 and added 0.1uF cap on input and change output cap to 2.2uF
- Added R6, 1k PD for unused address lines on flash chip
- Increased size of vias on 5V line and a few other minor routing changes to increase ground plane coverage

Many thanks!
45
Project development, ideas, and suggestions / Re: XT-IDE adapter with CPLD builds
Purely from an asthetics point-of-view, the SOT-223 package is pretty big compared to everything else on the board.  Testing so far hasn't indicated a problem with the 150mA available from the MIC5205 but I too have been wondering whether a bit more jiuce might be beneficial.  Hopefully we'll soon know whether the DPv2 board will work with older ATA drives so it's something we may need to re-visit!

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