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88 lines
3.6 KiB
88 lines
3.6 KiB
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\documentclass[11pt]{article}
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%Gummi|065|=)
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\usepackage{graphicx}
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\usepackage{caption}
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\usepackage{xcolor}
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\usepackage[vcentering,dvips]{geometry}
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\geometry{papersize={6in,9in},total={4.5in,6.8in}}
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\title{\textbf{UserSpace IO via uLisp and Arduino Uno}}
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\author{Steak Electronics}
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\date{}
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\begin{document}
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\maketitle
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%\tableofcontents
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\textcolor{green!60!blue!70}{
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\section{UserSpace IO via uLisp and Arduino Uno}}
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Overview: Goal is to get an easy way to echo "command" > /dev/ARDUINO from GnuLinux userspace.
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Then I can 3D print a box, throw some LEDs in there, and get a hardware interface for anything from my distro.
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\subsection{Setup}
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First off, I installed the stable uLisp from ulisp.com (AVR version 3.4).
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\subsubsection{Trouble with interfacing directly to ttyACM0 / ttyUSB0}
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The Arduino Uno uses an FTDI USB to Serial chip. It also has more than just RX/TX connected (I think). This means that when you echo "something" to
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arduino, this command will open the serial connection, send the command, then close the command and possibly reset the board via one of the
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UART reset pins (DTS perhaps). This won't work. First thing to do, get an FTDI board, and connect it to the computer, the connect
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it to digital pins 0,1 (for UART). Then test sending a command. This works. This will be the final setup. Computer -> FTDI -> Arduino.
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It should be possible to get it to work without the FTDI chip, but not without some debugging. Have at it, if you wish. I don't have time to troubleshoot this now.
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I tried a few things (exec 3<>, and the stty) neither worked. You could also use Python, but then that's more dependencies. Bad idea. This
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should be simple.
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Ref:
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https://forum.arduino.cc/index.php?topic=61127.0
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https://arduino.stackexchange.com/questions/16776/how-to-connect-arduino-device-to-linux
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https://stackoverflow.com/questions/3918032/bash-serial-i-o-and-arduino
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\subsubsection{Troubleshooting Code}
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The first thing you will want to do is prove that you can echo or cat "code" > /dev/ARDUINO.
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This code works:
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\begin{verbatim}
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(defun b (&optional x)
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(pinmode 13 :output)
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(digitalwrite 13 x)
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(delay 1000)
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(b (not x)))
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(b)
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\end{verbatim}
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Save it as a text file, then cat the file into /dev/ttyUSB0 or /dev/ARDUINO. Problem is, that code runs indefinitely. You can't tell it to do anything else. Hit the reset button to restart the Uno back to square one. So instead, you want a loop that runs and then stops. Here's one of those:
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\begin{verbatim}
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(defun b ()
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(pinmode 13 :output)
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(digitalwrite 13 nil)
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(delay 500)
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(digitalwrite 13 t)
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(delay 200)
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(digitalwrite 13 nil)
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(delay 500)
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(digitalwrite 13 t)
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(delay 200)
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(digitalwrite 13 nil)
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(delay 500)
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(digitalwrite 13 t)
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(delay 200)
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(digitalwrite 13 nil)
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(delay 500)
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(digitalwrite 13 t)
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(delay 200))
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(b)
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\end{verbatim}
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This works. Save it as a .dat or .txt (whatever) and cat file.txt > /dev/ARDUINO. It will run a few times, then stop. You can echo it again, if you wish.
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There, now we have an interface, and we have proven we can switch an IO high. With a couple of functions, it's trivial to go from there.\footnote{i.e. have one function set IO high for a given pin. Have one function set IO low. Have one function blink IO some amount of times. This can be used for counters or shift registers.}
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Tip: When building code, copy and paste into the Arduino Serial Monitor first. This way, if there's an error, it will tell you what's wrong. After
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you've tested the code, then you can put it in a text file. As we are keeping this simple, we don't have logging setup, or anything else. This is
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meant to be for basic IO from user space, not C compiled programs. Think lightweight.
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\end{document}
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