Teaching the Speak & Spell four (and more) letter words


Before it became the darling of circuit benders the world over, the Speak & Spell was a marvel of modern technology. Complete with a microprocessor and voice synthesizer, the Speak & Spell was able to speak a limited vocabulary that [Furrtek] thought should include words such as, “al qaeda”, “necrosis”, and “butt”. The Speak & Spell included an expansion port for cartridges containing a larger vocabulary, and with a huge amount of effort [Furrtek] created his own Speak & Spell carts that allow it to talk like a sailor.

The Speak & Spell ROMs were stored on a very strange memory chip; instead of a parallel or serial interface, the chip reads five nybbles at a time before returning the saved data. At first, [Furrtek] thought he could get an ATtiny microcontroller, but the way this memory chip is set up made it impossible to send and receive data even on a 400kHz I2C bus.

The project eventually found some decent hardware in the form of a CPLD-based cartridge that was more than fast enough to interface with the Speak & Spell. After that, it was only an issue of converting words into something the speech synth can understand with some old Windows 3.1 software and finally burning a ROM.

The end result is a Speak & Spell with a perverse vocabulary and is much, much more interesting than a circuit bent piece of hardware with a few wires crossed. Check out the video after the break.

[Read more...]

Bora board teaches binary hardware

If you’re just starting out in your quest to build really cool electronic devices, you’ll find a ton of options ready for the beginner. The Arduino makes toggling pins dead simple, and the Raspi brings the wonders of blinking a LED from the command line down from the gods and into the hands of the common man. These are all software platforms, though, and if you want to learn digital logic with hardware the best option is still a drawer full of 7400-series logic chips.

[Colin O'Flynn] hopes to change this with a beginners board for digital logic hardware design. It’s called the BORA, or Binary explORer boArd, and brings digital logic to a convenient package that is far less frustrating than a breadboard full of logic chips.

The BORA is based around a CPLD – a cousin of the FPGA-powered devices we see from time to time – that allows any student of digital logic to program the device and fill macrocells with NANDs, NORs, and ANDs.

The Xilinx device used in the BORA has about 1600 gates that can be programmed; more than enough to complete all the projects in the online lectures [Colin] has put together. You can check out the documentation for the BORA over on the official site, and the demo video after the break.

[Read more...]

Measuring projectiles with OpenChronometer

[Spork] over on the Netduino forums wanted to push the limits of what his little board could do. He put together a chronometer to measure the velocity of rifle rounds and Nerf darts using an Arduino-compatable CPLD shield.

The project is built around a pair of commercial CED M2 chronograph sensors; because people have the tendency to shoot through these sensors, they’re available as replacement units for much less than the cost of a complete chronograph setup. [Spork] couldn’t figure out a way for his Arduino clone to read pins with a resolution of 1 microsecond, so a Amani GTX CLPD shield was added to the build. This programmable logic chip takes the output from a chronometer sensor, starts a timer, waits for the second sensor to trigger, and stops the timer. From that, the velocity of just about any projectile can be calculated.

Of course, [Spork] needed to test his new device, so he took it out to the range and fired 25 rifle rounds through his chronometer. The result was a very nice, normal distribution centered around 2400 feet per second, exactly as would be expected. Although [Spork] didn’t test out low-velocity projectiles such as Nerf darts, we expect the same reliable results.

via majolsurf