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Project Notes

#670 Nano/ExpansionBoard

Testing and reverse engineering a cheap Arduino Nano Expansion board, also pondering why GVS instead of GSV or GVSG.



Another impulse buy: Nano Multifunction Expansion Board for S$1.30 from an aliexpress seller.

Features of the board:

  • 5.5 x 2.1mm barrel jack for power supply (recommended input voltage for Nano: 7-12V)
  • additional red LED 5V power indicator
  • additional AMS1117 3.3V regulator
    • tantalum and ceramic input and output smoothing caps
    • bank of 3 pairs of 3.3V + GND pins
  • “GVS” (ground - voltage - signal) pin banks for each GPIO of the Nano

Circuit Design

Sketching the schematic for the additional components that make up the expansion board:



Testing the board with a Nano installed:


An Aside on GVS

GVS is an unofficial standard for positioning ground and power with each signal pin:

  • 0.1” pitch pins
  • Ordered: Ground - Voltage - Signal

There are a large number of modules for input or output (e.g. sensors) that have a GVS connector. There is a 4 wire version (GVSS) for bidirectional serial communications.

I guess the original thinking was to keep the power wires together, and then add 1 or more signals to the end.

However on an expansion board like this it does mean a bit of a missed opportunity:

  • if the order was GSV, then 2-pin jumpers could be used to pull the signal pin high or low
  • with GVS, a 2-pin jumper can only be used to pull the signal high.


Perhaps a better design for an expansion board would be to put headers for GVSG:

  • the GVS part could be used for standard GVS cable connections
  • and the VSG part could be used to pull signal high or low with a 2-pin jumper

Credits and References

About LEAP#670 Arduino
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This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is just my personal collection of projects, usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting (IMHO!).

The projects are usually inspired by things found wild on the net, or ideas from the sources such as:

Feel free to borrow liberally, and if you spot any issues do let me know. See the individual projects for credits where due. There are even now a few projects contributed by others - send your own over in a pull request if you would also like to add to this collection.