This Tech Note describes the Arduino Mega SRAM expansion shield kit (and PCB). The design for this shield comes from Andy Brown – – where he has detailed all the relevant information. So, this Tech Note is not a full description, rather just the relevant links and additional information. (Refer to Andy’s website for all the details!)

Update – 5 July 2014

The Arduino software for this SRAM expansion shield kit is now available from this site. You can find details on the xmem software page.


The circuit diagram for the Arduino Mega SRAM expansion shield is shown in Figure 1. It’s pretty straightforward, noting that the interface lines for the expansion shield are provided through pins 22-43 of the Mega’s digital interface. The RD/WR lines are on lines 40 & 41 and can be optionally connected to LEDs to show that data is being read and/or written.

Figure 1 – Circuit diagram for the SRAM expansion shield

The full circuit diagram is A4 in size – the details may end up being too fine when viewed as an image. Therefore it also available as a PDF for those interested: SRAM expansion shield circuit diagram


Suitable software for the expansion shield is available from – it provides for the use of the SRAM by accessing one of eight banks of memory each of approximately 64 kB in size.


Andy Brown, –

  1. 512Kb SRAM expansion for the Arduino Mega (design)
  2. 512Kb SRAM expansion for the Arduino Mega (software)