Ventris

The Project

A breadboard-based Tetris game built by children in grades 4-6. Based around a PIC16F628A microcontroller, the kit allowed the kids to play Tetris on most any NTSC television.

Design Constraints

  • Cost – A very limited budget was available per kit was available so a strategy of low parts count and donated parts was pursued.
  • Ease of Assembly – As the kits were to be assembled by children on breadboards the circuit had to be as simple as possible.
  • Fun – The final product had to be worth the effort for the kids.

My Role

  • Simplification of Existing Design. The project was based on Rickard Gunee’s PIC Tetris game. As our implementation was one player only, several components could be eliminated, but first the code had to be modified to ensure proper operation.
  • Troubleshooting & Programming. The provided NTSC firmware had issues with vertical synchronization, as determined by examining the video output on an oscilloscope. The VSync code was examined and corrected for proper NTSC operation.
  • Circuit Board Design. A carrier board holding the RCA video jack, 4 controller buttons and providing connection between the two breadboard power rails was developed, as these components did not have breadboard-compatible spacing.
  • Parts Layout. A template for the breadboard was required, and revised with experience from observing assembly.
  • Troubleshooting. As very young children built the kits, many unique construction problems were encountered.
  • Training and Documentation. Counsellors had to be trained in how to build the project.

Lessons Learned

  • Designing for childrens’ kits – The kids had a great deal of difficulty with the breadboards, often inserting wires too far in, thus causing shorts and leading to overheating and exploding batteries. Also, parts were very frequently installed incorrectly making troubleshooting much more difficult.
  • Designing Circuit Boards for Breadboard Expansion – When designing the carrier board to hold the video jack and control buttons, issues were encountered with varying spacing of the power rails on breadboards. As a result, we had to carefully control which of our breadboards were used for which project, as only some of them would fit with the carrier board.

Photos