Power consumption nanoKenbak-1

[Rolf Strand]

I have been reviewing the schematic and code from   https://github.com/funnypolynomial/Kenbakuino

I like the use of higher efficiency LEDs compared to the original, that saves some current compared to the original text schematic.

I see that the SPI is bit banged.  The micro spends much of its time twiddling bits when it could be in sleep mode instead.

Any idea why the the hardware SPI peripheral was not used to drive the shift registers?

The Atmel app notes provide work arounds for the ISP programming.

Why are the Output LEDs not just driven by the PORTD directly eliminating the 74HC595?

The max output current of the 74HC595 is lower that of the mega.

Another mode would be to drive the LED's with lower value series resistors but with a duty cycle. This can usually result with the same visible intensity but lower average current draw.

Use of the Arduino delay function instead of a timer interrupt and use of the micros sleep state could also reduce current.

It seems that a new layout could reduce parts count and really reduce current draw.

 

[Mark Wilson]

Power consumption was not even a remote consideration when I wrote the code (10 years ago).

[wjst...@hotmail.com]

Someone asked Billy Nakamoto, the designer of Dogecoin, if he tried to consider energy usage in the design of it... his response was classic as well.  " i made doge in like 2 hours i didn't consider anything!"

These are things that people do to feel good about themselves... but it's not something a hobbyist will take into account when you're just playing around.  Things like using a lower power LEDs or which pin is used to drive it are not important... you use what you have laying around and hack it together, once it's working, optionally you can revisit it to make it better... but most of the time is spent debugging it and getting it working in the first place.  If he was going to make it an industrial design or sell a million units, then those are things you might think about.

[Rolf Strand]

This might be a minimum parts configuration.  Should be able to sleep, wakeup on timer interrupt, scan buttons, run emulator, update LED mux and go back to sleep.  Have not built it yet to verify.

[fcpr...@gmail.com]

Who wants to tackle the firmware changes? :)

I have a spare Uno hanging around, so I could help test!