wafer.space Community - KianV PCB HelpCenter

16:32

@GoranMahovlic (edited)

The asic/sdram operates at 30 MHz

16:46

isn't critical - I think

@asic destroyer - I've done 720p60 over pin headers for HDMI - that is like 750MHz signals....

1

asic destroyer changed the channel name: KianV PCB HelpCenter 12/18/2025 20:59

@RebelMike My question was: should I place the SDRAM on the bottom side or on the same side (top)? The connector is giving me a headache, because it forces a lot of distance to the SDRAM and the rat’s nest looks kind of weird. I’m planning a 4-layer board, and my reference is a Machdyne “Kuchen” board.

21:05

21:07

21:07

@RebelMike I hope it's now clear (edited)

I haven't started looking at this connector yet, but I would expect there to be plenty of space for the RAM chip under the board so you don't need to push it out away from the connector

21:34

The amount of crossing isn't ideal (I guess in an ideal world we'd have considered the connector pinout and eventual host PCB when choosing the pin assignment for the ASIC, but I certainly didn't do that). But if you do mostly vertical on one layer and horizontal on another it'll probably work out ok.

1

Unfortunately I also focused only on the ASIC and only today I realized what the impact on the connector/PCB is… I’ll work with two sides and a 4-layer stackup… Do you have any ideas for the clock frequency generator—can you recommend something? I don’t want an MCU on the board.

I’ll work with the top and bottom side. Thank you.

I'm no expert, but maybe an SN74LVC1GX04 and an appropriate crystal

1

I forgot to mention that I have 300× CH32V003. We could use one as a clock generator

22:40

https://de.aliexpress.com/item/1005005036714708.html

Seems not ideal

22:52

cmos 4-pin xo with socket seems a good solution