• 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
A few questions about a homemade Sdram Shield
#1
Hello to all,

I wanted to experiment with the V3 mojo with the sdram shield and realized it takes a little too much money and time to receive it.

So I made the sdram shield manually by modifying the original.
As I could not find the same memory chip inserted on the official shield.
 (I turned the house over to find an old pc133 sdram bank and I'm sure there are but I couldn't find the cards Undecided  ).

So I unsoldered one from an old hd (K4S641632K-UC60) Big Grin
 4 x 1,048,576 words by 16 bit -> 8Mbyte if I'm not mistaken (16 bit words are found everywhere)
Organization Row Address Column Address
4Mx16 A0~A11 A0-A7

It is a little different from the original it has 8 extra bidirectional data pins and
two data mask control pins and has one less addressing bit.
but I think it is compatible and now I'm editing the example file to do some tests.

My questions are these:
- there is a possibility of frying Angel  mojo if I am wrong in setting the doors
 bidirectional data of the sdram?

- is it possible to use it in 8 bit format without modifying the example file?

- I have never used sdram and on some schemes they are inserted
 25 or 33 OHm resistors in series usually to the data pins.
 In fact on the HD card are inserted at least the 16r on these pins.
 I believe it is used to eliminate disturbances (stub resistor).
 Do you think they need a test shield? seen that on the original
 there are not?

I powered the card without the mojo and it seems to work, by measuring the voltages on the pins they are floating or at Hz since the chip is not initialized and it absorbs a few mA.

Fabio
  Reply


Messages In This Thread
A few questions about a homemade Sdram Shield - by tistructor - 11-09-2020, 11:52 PM

Forum Jump:


Users browsing this thread: 1 Guest(s)