drewp

The 24 LED CCTV Camera IR Board FY-2024 PB is available for about $4 on ebay including shipping. Its circuit board says KL-Q5-24C.

At 9VDC, it takes about .15A (when the LEDs are on). The output is pretty tightly focused, kind of like you'd expect from an LED flashlight. The IR LEDs fade on gently as the amount of visible light on the sensor goes down. Of course, you could permanently cover that sensor if you wanted the IR lights to always be on.

I got this cool LCD from Adafruit. It has a tutorial for connecting it to an Arduino.

I wrote a tiny driver with web.py and spawning. Spawning has the cool feature of being able to use eventlet to handle multiple simultaneous requests in one process, in one thread. This helps me share my single USB port with all the requests; I didn't have to write any special queuing stuff. I would have gotten that property for free with twisted, too, but twisted.web and nevow are more complicated to use.

My code is essentially this:

import web, serial

ser = serial.Serial(port='/dev/ttyUSB1', baudrate=9600, timeout=1,

                    xonxoff=0, rtscts=0)

class index(object):

    def POST(self):

        ser.write("\xff" + web.data() + "\x00") # I made up this protocol and implemented it on the arduino side

        return "ok"

urls = (r'/', 'index')

app = web.application(urls, globals())

application = app.wsgifunc()

# spawn --port=9017 --threads=0 host.application

This is probably more than one needs just to connect an LCD to a computer, but I intend to run several other sensors and light controls off the same Arduino, so my web server will be getting more elaborate.

In the meantime, I can run unix shell commands onto the LCD:

% forever { date | curl -d @- http://dash:9017/; sleep 1 }

Or I can do a live search on twitter and display its results on the LCD:

import sys, restkit, jsonlib, urllib

login = "...", "..."

keyword = sys.argv[1]

response = restkit.request(

    "http://stream.twitter.com/1/statuses/filter.json?track=%s" %

    urllib.quote(keyword), filters=[restkit.BasicAuth(*login)])

for out in response.body_stream():

    text = jsonlib.read(out)['text']

    print text

    restkit.request(method="post", url="http://dash:9017/", body=text)