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FAST Nano Expansion Hat

Part Number: FP-CPU-0103

The FAST Neuron Controller, introduced in 2022, includes RJ-45 jacks to connect to the FAST Expansion Bus and the FAST Display Bus.

The FAST Nano Controller, introduced in 2016, does not have these ports. However, the design for the Nano was future-proofed, so this Nano Expansion Hat plugs into your Nano and adds 2 Expansion ports and 1 display port (same as the Neuron and our Retro Controllers).

This is possible because the USB interface on the Nano provides 4 endpoints, but only two were used. (NET and RGB LED), so this connects those two unused ports to the EXP and DSP busses. (Click to zoom the images below.)


  • Adds 2 Expansion Bus ports, and 1 Display Bus port to a FAST Nano Controller
  • 12V power input provides bus power for the added ports

Serial Interface

When you have the Expansion hat installed, the following four ports are available on the Nano:

Port Processor Description Baud
Port 1 DSP Display Bus 230400
Port 2 NET FAST I/O Loop Processor 921600
Port 3 RGB RGB LED Control 921600
Port 4 EXP Expansion Bus 921600

Note that the port numbers in the chart above indicate the relative order of the virtual ports that appear when you connect the Nano to your computer. The exact names / numbers will depend on your specific computer.

Firmware Updates

No firmware update is needed to use the expansion hat. The hat is essentially "pass through" to whatever devices are attached to the other end, so if you add the Expansion Hat, but do not connect any devices to the other end of one of the busses, then you will not see anything via the serial connection (e.g. no response to id: command) since there's nothing on the other end to respond.

12V power input

The Nano Expansion Hat has a 2-pin, 0.156" header J1 labeled 12V PWR which is INPUT power which is transmitted to devices via the display or expansion bus. However, not all devices need this power, as the baseline low-current power to run the logic comes from the Nano via the headers to the hat. (For example, regular expansion boards, such as the FP-EXP-0071 and FP-EXP-0081, do not require this extra power, since they have 12V inputs locally.)

So this input is not needed generally, and we will specifically call out expansion bus or display bus products that need it.

Soldering required

The Nano Expansion Hat has five headers that attach to rows of pins on the Nano. Most Nanos shipped without all these pins attached, so when you buy the Nano hat, it includes the rows of pins you need. You will need to solder these pins to your Nano. (The pins become permanent, but the hat can be removed.)

Here's a view of the bottom of the expansion hat. No soldering is required here, rather, you need to solder the pins these connectors plug-in to on the Nano.

The Nano Expansion Hat includes these header pins. The following diagram shows where these header pins need to be attached. (The pins are already soldered on in this image.)

Header 0.100" pin layout
J3 2x3
J6 2x5
J8 1x3
J9 1x3
J12 2x5

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