The Ben Heck Show

Ben Heck's Atari Junk Keyboard Enter the Matrix (1) (6x39)

Fecha de emisión: Oct 28, 2016

The team begins working on an Atari Junk Keyboard, a version of the Atari Punk Console that combines 555 timers to make a simple circuit that makes Atari-like music and sound effects. Instead of using sequences to repeat Atari-like sounds they decide to make a whole keyboard of the sounds. B The plan is to take the matrix from a set of keys to figure out how they work, add discrete logic by using a circuit to read keys instead of opting for a microcontroller, and then feed that input into a number of Atari Junk Console integrated circuit pairs resulting in multiple sound effects playing at once. They begin their project by first getting the keyboard matrix working so they can later attach it to the Atari Junk Console to make music. Ben begins by wiring up an oscillator. An oscillator is different than a crystal in that the oscillator can output its own waveform whereas a crystal you have to attach something else to it in order to get a square wave. The 1mhz oscillator has power and ground going into it and pins for enable and output. When you hook up power and an oscilloscope to the output pin you should see a 1mhz square wave coming off of it. As that may be a little too fast for the switch matrix a CD74HC4017 Johnson Decade Counter is used to divide the frequencies. A second Johnson counter is also added. On the first Johnson counter one of the outputs is going into the clock input of the second Johnson counter. This prevents 2 useless cycles and keeps timing more consistent. Next he hooks up the outputs of the Johnson Counter to an inverting buffer that will drive the columns as well the flip flop driver that will load the data off of the switches. He uses an Inverting buffer 74HCT540 and wires it so that it so that it goes onto his breadboard. He does more analysis on the oscilloscope after he wires outputs from the Johnson Counter to the Inverting buffer and decides to use another Johnson counter to drive the flip flops. Ben attaches 8 octal fli