Computers

Well, it is here, it arrived and it works. I already made my first measurement just to see if it actually alive. It is, it so is... 

So, anyway, I always wanted to know what it feels to interact with a digital circuit directly from BASH, now I have it, I did so. Wonder how wide an impulse when it is sent from a BASH script? Now here it is...

I connected a Raspberry PI to the signal analyzer, then wrote a little BASH script to switch the Raspberry GPIO ports on and of continuously. Well, first it did not show no matter what I did, then I realized I was running the script on pi1.homelab.local and that's on the other bench... but then, scp, login, bash and the signal came. Well, once I connected the real GND and not the wire I thought was GND, but I am just a human after all. Right?

So here is the script that I run. Low level, as low as low it can be from BASH. The "echo" is a BASH internal, that' important...

#! /bin/bash

echo "2" >/sys/class/gpio/export
echo "3" >/sys/class/gpio/export
echo "4" >/sys/class/gpio/export
echo "17" >/sys/class/gpio/export
echo "27" >/sys/class/gpio/export
echo "22" >/sys/class/gpio/export
echo "out" >/sys/class/gpio/gpio2/direction
echo "out" >/sys/class/gpio/gpio3/direction
echo "out" >/sys/class/gpio/gpio4/direction
echo "out" >/sys/class/gpio/gpio17/direction
echo "out" >/sys/class/gpio/gpio27/direction
echo "out" >/sys/class/gpio/gpio22/direction

while true; do
	echo "0" >/sys/class/gpio/gpio2/value
	echo "1" >/sys/class/gpio/gpio2/value
	
	echo "1" >/sys/class/gpio/gpio3/value
	echo "0" >/sys/class/gpio/gpio3/value
	echo "1" >/sys/class/gpio/gpio3/value
	echo "0" >/sys/class/gpio/gpio3/value
	
	echo "1" >/sys/class/gpio/gpio4/value
	echo "0" >/sys/class/gpio/gpio4/value
	
	echo "1" >/sys/class/gpio/gpio17/value
	echo "0" >/sys/class/gpio/gpio17/value
	
	echo "1" >/sys/class/gpio/gpio27/value
	echo "0" >/sys/class/gpio/gpio27/value
	
	echo "1" >/sys/class/gpio/gpio22/value
	echo "0" >/sys/class/gpio/gpio22/value
done

Oh, by the way, sorry about the image quality. The batteries in my camera flashes are all down, the tripod is somewhere in the other room and it is too late to be a perfectionist. Anyhow... the analyzer looks like the script, the pattern is the same. And if you wonder how wide those impulses, they are 80 microseconds. Not bad from a shell script...