I made a simple 3D printed bracket for the QT Py and keyboard connector and printed it using standard settings. If you want to modify the bracket, you can pick up the design files which are in OpenSCAD format.

The QT Py clip in design is taken from the guide "QT Py Snap Fit Case".

Wiring & Assembly

First, wire the DIN connector and install it in the bracket. Then, install the QT Py in the bracket. Finally, wire the QT Py.

For all wiring, follow the wiring table below, taking care about the orientation and peculiar numbering of the DIN connector.

The photos show six different colors of wire for clarity. You don't necessarily need to use six different colors but if you use fewer you'll need to take extra care to get the wiring correct.

The keyboard was originally designed to be powered from 5V, but during testing powering it with 3.3V worked fine, and it removes any concern about voltage level conversion.

Color Code

DIN Position

QT Py Position

Purpose

Black

3

GND

Ground

Red

5

3.3V

VCC (3.3v is OK)

Yellow

2

MOSI

Busy (active low)

Green

4

SCK

Clock Out

Blue

6

MISO

Reset (active low)

White

1

RX

Data Out

The following image from Wikipedia shows the DIN connector numbering seen from the front side on the socket (female). When you work on the solder side of the socket, the pins are mirrored or reversed so that if the keying notch is on the bottom, 1 will be on your right and 3 will be on your left.

In the following Fritzing diagram, the connector image has been pre-flipped, so pin #3 is at the left, #2 is at the top, and the keying notch is at the bottom. This is how you will view the connector while soldering it.

Solder the DIN connector

Take six lengths of wire, 100mm (4in) each is sufficient. It's easiest if you use six different colors as shown in the photos, but at the risk of getting your wires literally crossed you can use fewer colors. Strip one end of each wire and solder them to the DIN connector according to the wiring table. It may help if you twist the strands of solder together and then bend it part way back, to make a little hook that grabs the eyelet.

Install the connector & QT Py

Take the included nut off the DIN connector. Stick the DIN connector through the large circular hole in the print, then put the nut in from the back side. Orient the keying notch up and tighten the nut.

Take the QT Py. Point the USB connector "outwards" from the bracket, and press it firmly into the clip until it snaps firmly into place.

Solder the QT Py

Starting with RX and working outwards to GND, shorten each wire to a more appropriate length and then strip a very small amount (around 2mm).

Insert the wire into the top of the QT Py and while holding it in place use a small amount of solder to bond it firmly to the pad.

Repeat until all wires are soldered. Once you've double checked your wiring according to the table and images above, you can proceed to coding the Tandy 1000 Keyboard, stopping off at the Installing CircuitPython page if your QT Py doesn't have CircuitPython installed yet, or it's not up to date.

This guide was first published on Sep 27, 2022. It was last updated on Jul 17, 2024.

This page (3D Printing & Wiring) was last updated on Mar 08, 2024.

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