Electronics > Repair

Has anyone replaced HP8591(E) SRAM by FRAM?

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Miti:

--- Quote from: MarkL on January 18, 2025, 12:37:13 am ---Certainly with the addition of various logic it's possible to make any scenario work.

Since moving the SRAM contents only needed to be done once, I was trying to keep it simple and make the programmer do all the work without building any additional circuitry.  My 8 step proposal uses jumpers and a resistor or two.

--- End quote ---

By the time I draw the schematic, I cut the wires, I strip, I solder, I curse... I'd rather have it done right and order it together with the main board.

Edit: This also can be used as test platform. If reading and writing works on this adapter, it is more likely to work in the spectrum analyzer.

Miti:
Something like this. I've looked for a proper switch instead of a jumper but boy oh boy! $10 for a proper slide switch? What a world, what a world...

Miti:

--- Quote from: MarkL on January 14, 2025, 09:03:07 pm ---In the scope capture in Reply #18, it would be better to trigger on LUSERRAMx == LOW (HM638128 /CE == LOW).  LLW and LUW might be toggling with peripheral accesses, and if so, you're not necessarily capturing exclusively what the HM638128 is experiencing.

Can you post a capture of LxW, LOE, LUSERRAMx signals during a memory read cycle, and during a memory write cycle?

--- End quote ---

Here it is. Ok, LLW (and I assume LUW as well, from my previous scope shots most writes are 16bits, but I ran out of channels  ;D) does toggle with peripherals, so what? If no RAM is selected, both FRAM and the buffer are disabled. The write cycle is ignored.
Do you see any conflict in the attached scope shots? What else do you think I should look at?

Cheers,
Miti

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