Available pins for uArm Metal?

I have been under the impression that there were no unused pins on the uArm and that using the primary serial connection was the only option.

However, I recently saw the following showcase video titled “Control uArm Metal With Ultrasonic Sensor” and this shows a developer making use of what appears to be 2 pins located on two unused 4x1 headers of the AIO.

Can someone actually confirm the use of these pins and whether they are actually available for development use?


Hi, Dava,

This is Joey. I made this showcase actually, there are two more available pairs of pins (D8 and D9) in UARM and UART communication port (if you do not use bluetooth)

Check the pic http://developer.ufactory.cc/images/pinout.jpg (shows in developer page). The D8A7 pair and D9A6 pair. And ultrasonic sensor need ECHO and TRIG two pins, so wire them into D8 and D9 respectively. Then you can use them.


That’s terrific! So D8 and D9 are available from those two headers, what about A6 and A7? Are these additional analog pins?

And in addition to power and ground on the Bluetooth header, are the other two pins D1 & D2 in a standard TTL serial?

This is excellent news as it would allow for a certain amount of debugging or signaling through an additional software serial port on D8 & D9.

I hope you are all enjoying the new year celebration and some needed vacation!


Sorry, I meant to confirm the Bluetooth header was the standard TTL serial on pins D0 and D1. Is this correct?

We do have D2, but that is for stopper in the end-effector side. Bluetooth will use the UART to communicate (TX RX). Just treat TX and RX as your D1(TX) and D2(RX)


So just to confirm, pins D8 and D9 are available digital GPIO pins?
Also are A6 and A7 unused analog pins?

Are D8 and D9 standard voltage/current pins for an Arduino?

I have used each of these pins as 5v TTL for various things. I have not actually tried using analog input, but I have no reason to think it would not work.

I do not know the current available, whether they would carry the higher current of the servo pins or a more standard 40mA.