Level Shifter options

BigEd edited this page Jun 10, 2017 · 15 revisions

The Acorn Tube interface uses 5V levels, where as the Raspberry Pi's GPIO header uses 3.3V levels, therefore some kind of a level shifter is required, or else damage will result.

There are currently four options:

Kjell's Level Shifter board (or kit)

Kjell Sundby has published a design of an interface board here and is also selling this board and another board at a reasonable price - see here. This design is popular and has been successfully used by many people. You will need to decide whether you want a cable-connected universal version, a compact under-Beeb version, or an in-Master version.

Kjell board under BBC Micro

Purchase a Tube Silencer and some Jumper Cables

The Tube Silencer is made by John Kortink, and can be purchased here. (Also shown is a serial connection, needed only for debugging during development.)

Breadboard a Level Shifter

This uses two 74LVC245A chips, which cost very little from Farnell.

Wait for our Level Shifter Pi Hat PCB

This is currently being designed on KiCAD v4. The design files are in Github: https://github.com/hoglet67/PiTubeDirect/tree/master/kicad

It is essentially the same as the breadboard design, with some optional components for signal conditioning, that hopefully will not need to be fitted.

Other options

Simon Inns has also designed a board and shared his design files here: http://www.stardot.org.uk/forums/viewtopic.php?p=143605#p143605

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