On 7/29/2023 12:36 PM, emanuel stiebler wrote:
On 2023-07-29 13:57, Bjoren Davis via cctalk wrote:
I never made a push to publish it because by the time I got to it the
parts (Cypress CY62167G-45ZXI SRAM and ATF1504AS-10AU100 CPLD) had
become unobtainable.
The SRAM can still be find, but the CPLD?
Any chance to replace it with something newer?
Possibly. This was only the 2nd PCB I ever designed, so I was very
conservative and used a CPLD. Now that the logic has been proven, I'm
sure the board could be reworked using just 5V-compatible flip-flops,
discrete logic, and a latch.
As far as using the board as it is: I think the only other possible CPLD
that would work would be the 25 ns version ATF1504ASL-25AU100. I think
that's still plenty fast enough, but it seems to be just as hard to get
as the original.
Maybe things have changed, but right now there are only 3 of these
boards. I have 2 and I think I sent the 3rd to you, Paul.
Any chance you like to have a look at it again?
Sure, I guess. As I mentioned I think the best thing would be to rework
it with discrete logic so as to really reduce the susceptibility to
future shortages. Even if it increases BOM and assembly costs.
The problem with reworking the board with a different CPLD is that it
needs to be a 5V-compatible CPLD, and it needs to be able to buffer half
of the address lines (9 in and 20 out). That means it needs a high pin
count. These two criteria quickly narrow the possibilities down to
almost nothing. Add to that the wanting a reasonable price and
availability for a few years and it really does go to nothing..
Digikey claims that the ATF1504AS-10AU100 is still an Active product and
expects new product in April, 2024. Maybe it just makes sense to wait?
