2 layers96.3 × 76.2 mm
Flash-32mbit
partlyhuman/floopydrive
The Floopy Drive, an open-source flashcart for Casio Loopy
33 parts30MIT
2 layers50.8 × 27.9 mm
Xmem
cduk/xmemAtmel External Memory Board XMEM interface
- Size
- 50.8 × 27.9 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 6
- Nets
- 43
- Pads
- 94
- Tracks, vias
- 339, 35
- Pours
- 2
- Routed
- Yes
- KiCad
- KiCad 4
- Created
- 13 Jun 2016
- Updated
- 10 Nov 2021
Overview
Xmem is an open-source printed circuit board by cduk, from the cduk/xmem repository on GitHub. It is a 2-layer board of 50.8 × 27.9 mm with 6 parts on 43 nets, routed with 339 tracks and 35 vias.
It is built around the AS6C1008-55SIN and SN74AHC573N. Its parts include 3 capacitors, 2 ICs and 1 connector.
Main components
2README
READMEThis is my first attempt at designing a PCB.
It is an expansion board for the Arduino ATmega to have an external SRAM chip.
I'm using the AS6C1008 128K x 8 bit chip as I happened to have several of these on hand. You can either use half of it, which is as much as the ATmega can address without banking, or you can bank switch using the A15 pin.
As this is only a 55ns ram chip, maximum clock speed should be ~18MHz without waitstates. I still need to test the board and chips to see how fast the RAM chips can actually be driven.
This PCB was designed from scratch by myself as a way to learn to use KiCad: http://kicad.org/
I have seen several other designs already including most notably:
http://andybrown.me.uk/2011/08/28/512kb-sram-expansion-for-the-arduino-mega-design/
Which I'm sure both influenced my own design both consciously and probably sub-consciously and so I want to make sure I credit Andy for this work.
Parts
6| Qty | Value | Footprint | References |
|---|---|---|---|
| 3 | C | Capacitors_SMD:C_0805 | C1, C2, C3 |
| 1 | AS6C1008-55SIN | SOIC127P1407X299-32N | U1 |
| 1 | CONN_02X18 | Pin_Headers:Pin_Header_Straight_2x18 | P1 |
| 1 | SN74AHC573 | Housings_SOIC:SOIC-20_7.5x12.8mm_Pitch1.27mm | U2 |
Questions
How big is the Xmem PCB?
It measures 50.8 × 27.9 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Xmem use?
6 parts, built around the AS6C1008-55SIN and SN74AHC573N. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the Xmem KiCad files?
From the cduk/xmem repository on GitHub, at the commit this page was made from: the board is xmem.kicad_pcb. PCBKit opens the board in the browser, with nothing to install.
Can I use the Xmem design in my own project?
Its repository states no licence, so its author keeps all rights: ask cduk before reusing the design.
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