Sunday, March 29, 2015

78: Controlling my Spark Core Wirelessly over the Internet

My Raspberry Pi can now read sensors and switch relays on my Spark and post results to a Web page! Details at --

Battery powered Spark Core

Tuesday, March 24, 2015

77: More About* Time Lapse with the Pi Camera

For my last example (post 71) I used the timing/counting features of the raspistill command to record my image sequence. But this time I want to capture a JPEG per minute from sunrise to sunset. Here's the shell program I wrote:

hr=`date +%H` # just the hour
while [ "$hr" -ge "07" ] && [ "$hr" -le "20" ] ; #e.g.: 7am to 8pm
  ct=`expr $ct + 1`
  num=`expr 0000$ct : '.*\(....\)$'`
  raspistill -w 1280 -h 720 -t 1 -o i${num}.jpg
  sleep 60
  hr=`date +%H`

The 2nd expr command makes sure that the $num variable is a zero-filled 4-digit number (required in the convert-to-movie step). Also, about 1975 I wrote the original UNIX expr command -- so I like to use it.

* Did you know that when millions of English words were checked, the first (most common) 130 were all one syllable. The first two-syllable word was "about." Does that mean something? Trust me, "exactly" was way, way down the list.

Monday, March 16, 2015

76: Raspberry Pi to Spark Core

It wasn't too painful. I have successfully sent a command to the Spark and gotten data back. My Core is sitting a foot from the Pi but it could be anywhere there's Internet. Details at my Arduino site:

Spark Core in its cute box

Friday, March 6, 2015

75: A New Way to Connect an RPI?

Spark Core: Where have I been? Sounds like what I've been looking for. See--

I ordered one. Let you know.