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December 06, 2021, 04:24:07 pm


SMF - Just Installed!

My own rework of the 512k mega ram expansion

Started by telanoc, November 18, 2015, 06:20:40 pm

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Hi, y'all.  I wound up making my own "clone" of Andy's Mega 2560 SRAM expansion, which uses a full-width connector across the end of the board, picking up power and ground.  I also moved the jumpers for the LEDs a bit.  And let Eagle do most of the routing.

I wound up doing 4 layers mainly because I could.  The board is on Osh Park at https://www.oshpark.com/shared_projects/5dhn3IBO

Board and schematic are on github: https://github.com/telanoc/mega2560_xmem

I've got one put together (jeez, I didn't realize how small those chips were) and it's working with no issues.

Andy Brown

Hi Pete, your board looks great. 4 layers huh? If you've got a continuous ground plane below the top then your signal integrity should certainly benefit from that.
It's worse than that, it's physics Jim!


Yes, I have one plane for VCC and one for ground (besides top and bottom).

Here's a pic of board #3, still needing a bit of flux cleanup.  I've been running the xmem::selftest() in a loop for 15 minutes or so.

By the way, a big "Thanks" for designing this thing in the first place.