Datel Robotek: A Recreated Robot Control Card for the ZX Spectrum
A faithful recreation of Datel's long out-of-production Robotek interface, corrected against the original schematics from Make and Program Your Own Robots.
TK-Pie: A Real HDMI Interface for the ZX Spectrum 48K
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The Spectrum's only native video output is composite/RF — fine on a period CRT, a fuzzy compromise on anything made in the last twenty years. TK-Pie is an edge-connector add-on board that solves this properly: it taps the Spectrum's bus directly, decodes the video timing on a CPLD, and hands the result to a Raspberry Pi Zero, which outputs real HDMI over a mini-HDMI-to-HDMI cable. No analogue-to-digital conversion artefacts, no lag from an external upscaler — just a clean digital picture straight off the bus.
This build uses the shared PCB design below, designed by Victor Trucco and released under a Creative Commons Attribution-ShareAlike (CC BY-SA 3.0) licence. Source code and schematics are on GitLab, with a full build walkthrough on the designer's blog.
Build notes
This is not a beginner solder-and-go board. The CPLD (an EPM240T100C5N, or the EPM7128 variant depending on which schematic you follow) needs to be programmed over its 2×5 JTAG header before anything will work, so a CPLD programmer is a hard requirement, not an optional extra. The ZX Spectrum's edge connector needs some physical modification to fit, and version 1 of the board calls for an optional 0Ω link resistor at R31 — easy to miss if you're going purely from the silkscreen.
Build video
Build video coming soon
Component list
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| Component | Qty | Notes | Source |
|---|---|---|---|
| TK-Pie interface PCB | 1 | Shared design — order directly from the PCBWay project page | PCBWay |
| Raspberry Pi Zero | 1 | Generates the HDMI output; mini-HDMI port | |
| CPLD, EPM240T100C5N (or EPM7128 variant) | 1 | Reads Spectrum video timing off the bus — must be JTAG-programmed before use | |
| ZX Spectrum edge connector, 28×2P, 2.54×5.08mm pitch | 1 | Requires modification to fit — see the build guide | |
| 40-pin female header | 1 | Raspberry Pi connection | |
| 2×5 JTAG header | 1 | For CPLD programming | |
| 330Ω SMD resistors (1206) | 30 | Bus line termination | |
| LM1117 3.3V regulator | 1 | CPLD/logic supply | |
| L7805 5V regulator | 1 | Raspberry Pi supply | |
| 100nF ceramic + 100µF electrolytic capacitors | 1 | Decoupling — see schematic for exact placement | |
| Mini-HDMI (Type C) to HDMI (Type A) cable | 1 | Connects the Pi Zero to the display |
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