V1.4 CPLD released. Supports 3 jumper fix (Fix pictured)

For people with technical questions about their CFFA Interface card. You can use this forum to communicate with me and with other CFFA users. If you are posting a problem, please be as detailed as possible, including any necessary sequence needed to cause the problem, your system information and any error messages.

Moderator: rich

V1.4 CPLD released. Supports 3 jumper fix (Fix pictured)

Postby rich » Mon May 02, 2005 9:15 pm

Hi All,

I am sorry to announce that after much work to determine why the CFFA card was having problems accessing the SanDisk 256MB cards, I have
discovered a design flaw that requires a board layout change. This change can be made to existing boards with the addition of 3 jumper wires.
I have now released V1.4 of the CPLD logic which supports the hardware fix. This v1.4 will still work with boards that do not have this fix in place and will provide better timing and may actually be enough in Apple IIgs machines to make the larger CF cards work. But to really fix the problem especially in all other II's the hardware fix is needed.

For those who are curious the problem stems from the fact that in the process of creating an ATA bus cycle from a 6502 bus cycles require that the end of the ATA cycle extend past the end of the 6502 bus cycle. The problem was caused because I was directly using A0, A1, A2 from the apple slot to drive the CF's address lines. Those address lines are not remaining stable through the entire ATA bus cycle and are changing near the end of the cycle. This did not seem to bother the smaller SanDisk cards, but the larger cards which probably have a different controller in them, would not work. Also many other brands of cards like Lexar, never work.

Now they work fine in my II+, IIe enhanced, and IIgs ROM1.

So as soon as I can get caught up on my remaining orders, I will start some kind of update process where people can send me their boards for update. Also I will post detailed pictures for those who want to do it themselves.

Note: Anybody who received a beta v1.4 CPLD, the final version 1.4 is different.

Here are pictures of the front and back of a CFFA with the 3 jumper fix.
The jumpers run from U4, pins 2,3,4 to U6 at the back of the board.
[img]http://dreher.net/projects/CFforAppleII/images/3jumperFix.jpg[/img]
[img]http://dreher.net/projects/CFforAppleII/images/3jumperFixBack.jpg[/img]
rich
 
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