MiSTer FPGA Forum

terminator2k2 wrote: ↑Sun Dec 27, 2020 11:48 am really needed to include HDMI output if you wanted the majority of the community to test this core

jotego wrote: ↑Wed Dec 30, 2020 10:26 am By the way, two people with no-failures for any of these MRA files told me they lived in areas with low population density (and hence less RF noise).

jotego wrote: ↑Wed Dec 30, 2020 10:26 am Just passing the RAM/ROM test at the game boot-up screen is enough. It's surprising that for some people all the files are good. By the way, two people with no-failures for any of these MRA files told me they lived in areas with low population density (and hence less RF noise).

jotego wrote: ↑Sat Dec 26, 2020 6:11 pm I want to share a test for signal integrity that doesn't require special equipment. This test gives some information about signal integrity in the SDRAM. This is a relative test: more is better.

The idea is to have a single core compiled with different SDRAM clock shift settings. Although indeed, the exact delay up to the pin is not well controlled (right now), as a relative measurement, this is reliable. I have made a collection of MRA and RBF files. Each one delays the SDRAM clock by 250ps with respect to the previous one. If you start at a middle value, like 5ns (=5000ps), it should work. As you approach lower and lower delays, it will eventually fail. So will it fail too if you move towards larger delays. The wider the range you get, the better.

These are the values I get for the modules I have.

Code: Select all

Module | Min  |  Max  | Remarks
-------|------|-------|---------
1      | 3.5  | 8.25  |
2      | 2.5  | 8.5   | 32MB
3      | 2.5  | 8.75  | 32MB
4      | 3.0  | 8.0   | 10uF added
7      | 4.0  | 8.25  | min improved to 3.5ns by adding 33uF
8      | 3.5  | 8.0   |
9      | 3.25 | 8.25  |

Module description

ID  | Part No          | Units | Size
----|------------------|-------|-----
  1 | AS4C32M16SB-6T1N |    2  | 128
  2 | W9825G6KH-6      |    1  |  32
  3 | AS4C16M16SA-6TCN |    1  |  32
  4 | AS4C32M16SB-7TCN |    2  | 128
  5 | W9825G6KH-6      |    1  |  32
  6 | AS4C32M8SA -7TCN |    2  |  64
  7 | AS4C32M8SA -7TCN |    4  | 128
8,9 | AS4C32M16SB-6T1N |    2  | 128

Note how module #4 with an extra 10uF electrolytic works better than comparable 128MB modules. #7 also improved when I added extra capacitance.

Please find the files attached. Just unzip them to your MiSTer root folder. This is mainly intended for module builders, but anyone can test their modules at home and check how they do against the ones listed here.

Note that these RBF files only produce analogue video. No HDMI output at all.

Lowest and highest also work for me - however, I also get HDMI output from them, which I thought was not present in these cores - so what is happening here ?

jotego wrote: ↑Wed Dec 30, 2020 10:26 am It's surprising that for some people all the files are good.