Hi Y'all!
We hope to see y'all
tomorrow at the RPUG Meeting at the library. I have been working on
getting a shift register to control the frequency played by an astable
555 timer. Two shift registers are connected to LEDs at this point so it
is pretty close. I am building the astable multi-vibrator right now.
The
idea is to test the breadboarded device with one shift register. That
will give it 8 bits to work with: 5V / 255 = 19.6 mV per bit.
Once
I get that running, I will expand the DAC to more than 8 bits, giving
more resolution to the frequency. Blah, blah, blah, until you realize
that with more bits, you get greater control over the tones you can
play. One of the interesting possibilities of using shift registers to
control R-2R DACs is that you control the bit resolution. You can pick
and choose how many bits are used to control each device. A web search
on R-2R DACs will give you the idea that I am talking about. I can take 4
bits from one shift register to add to the first shift register and
then use the remaining 4 bits to control something else.
An
Arduino Nano is the brains at the moment but it should work with any
other Arduino, even a 3V one, such as an Arduino Due. A 3V signal still
registers with 5V logic ICs as a high signal so all that stuff will
work. Watch out trying to go the other way, sending 5V signals to a 3V
device. Many 3V devices will be damaged by 5V signals.
See you tomorrow!
Look for the next post with schematics and equations for all that technical stuff.
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