Update Jan 2025: Some units have been built and are now available for purchase. The design has been updated with a USB type C power connector instead of micro USB. The new base plate and keypad support screws are also included.

Update May 2024: Thanks for your interest. FPGAs are available again. I will build some more PCBs later in the year.

Update Feb 2022: Temporarily out of stock due to severe FPGA shortages.

What is it?

Full details of the project and its development can be found here: VHDL Teletext: Overview.

Teletext is a system for transmitting pages of text and simple graphics in a hidden part of a TV signal for display on TV sets with an appropriate decoder. This system was originally developed in the 1970s, and remains popular today in Europe despite being little-known elsewhere.

An FPGA development board designed for the application of decoding WST (World System Teletext) and displaying it on a HDMI monitor/TV. The board is pre-programmed with my open-source VHDL-Teletext firmware and all you need is a USB power supply, HDMI or DVI monitor, and a source of teletext data with composite video out such as a Raspberry Pi running VBIT2 or a satellite receiver. 50/60Hz output and choice of 576p and 800x600 resolutions for compatibility with international TVs. Please note that this design does not convert composite video to HDMI, it displays teletext only.

The board is suitable for all manner of FPGA projects. The Altera MAX 10 FPGA has 8k logic elements which is enough for complex hobby FPGA projects. In addition to HDMI connectivity and the built-in keypad and buttons, 23 I/O are connected to headers to allow connection to other devices, providing the potential for diverse applications such as a Telesoftware decoder or a replica of an old microcomputer.

Why did you make it?

I made it because I wanted to create a Teletext decoder which does not depend on obsolete components and has a high-quality, modern, video output connection.

The unique combination of hardware features needed made existing FPGA development boards unsuitable. Limited stocks of old obsolete decoder chips are still available but these only have low-quality composite video outputs and usually only work with PAL TVs.

What makes it special?

This is the world's only standalone teletext decoder with HDMI output.

Development board hardware features

• 10M08SCE144C8 FPGA
• HDMI output with arbitrary resolution support* with proper current-mode logic level shifter IC
• Composite video input with high-speed comparator for WST sampling
• Micro USB power supply connection - typical current when running teletext decoder firmware is 100mA
• 3.3V 2A switching regulator (plenty of power for external electronics) and 2.5V LDO regulator
• 3-channel programmable oscillator
• 16-way DIP switch
• 20 buttons (including detachable keypad)
• Three I/O headers with 23 I/O pins
• Footprint for optional 512K SRAM for development purposes (can be used as extra I/O)
• Footprint for optional video processor IC (SAA7113)

* The pre-flashed image includes support for 720x576 and 800x600 at 50Hz and 60Hz. An alternative image with 1280x720 at 50Hz or 60Hz is available on the GitHub.

VHDL-Teletext firmware features

• Open-source firmware (GitHub)
• Level 1.0 teletext decoder with single-page memory
• Selected Level 2.5 and Level 3.5 features
• Resolution selection via DIP switches: 720x576 or 800x600 at 50Hz or 60Hz (640x480 possible with minor code modifications)
• Alpha Black enable switch for selecting between adherence to the original specification or compatibility with certain modern teletext services
• Power-on page number selection via DIP switches
• Mix function enables/disables the display of background colours (note that this board does not display the video portion of the composite video signal over HDMI)
• Subpage selection
• Reveal button displays and hides "concealed" page content
• Page selection via number keys, up/down buttons, and Fastext keys
• Level 2.5/3.5 store function for applying enhancements to Level 1.0 pages
• Accepts teletext packets on any line of the TV picture (unlike most decoders) which means the -f flag may be used with raspi-teletext to enable full-field mode, which achieves a dramatic improvement in speed
• Level 1 National option subsets implemented (foreign/accented characters) for English, German, Italian, French, Portuguese/Spanish, Czech/Slovak
• Parameterised design enables design tweaks without any programming knowledge

Included in your order

Pre-assembled VHDL-Teletext FPGA board with keypad