Categories
Raspberry Pi

Monitoring the temperature of my Raspberry Pi Camera

In late April of this year I wrote a script that would capture the temperature of the Raspberry Pi that sits above my Hummingbird feeder and log it to a file.

It’s a straight forward enough script that captures the date, time and temperature as given by the internal measure_temp function. In code it looks like this:

MyDate="`date +'%m/%d/%Y, %H:%M, '`"
MyTemp="`/opt/vc/bin/vcgencmd measure_temp |tr -d "=temp'C"`"
echo "$MyDate$MyTemp" >> /home/pi/Documents/python_projects/temperature/temp.log

I haven’t ever really done anything with the file, but one thing I wanted to do was to get alerted if (when) the temperature exceeded the recommended level of 70 C.

To do this I installed ssmtp onto my Pi using apt-get

sudo apt-get install ssmtp

With that installed I am able to send an email using the following command:

echo "This is the email body" | mail -s "This is the subject" user@domain.tld

With this tool in place I was able to attempt to send an alert if (when) the Pi’s temperature got above 70 C (the maximum recommended running temp).

At first, I tried adding this code:

if [ "$MyTemp" -gt "70" ]; then
   echo "Camera Pi Running Hot" | mail -s "Warning! The Camera Pi is Running Hot!!!" user@domain.tld
fi

Where the $MyTemp came from the above code that get’s logged to the temp.log file.

It didn’t work. The problem is that the temperature I’m capturing for logging purposes is a float, while the item it was being compared to was an integer. No problem, I’ll just make the “70” into a “70.0” and that will fix the … oh wait. That didn’t work either.

OK. I tried various combinations, trying to see what would work and finally determined that there is a way to get the temperature as an integer, but it meant using a different method to capture it. This is done by adding this line:

ComparisonTemp=$(($(cat /sys/class/thermal/thermal_zone0/temp)/1000))

The code above gets the temperature as an integer. I then use that in my if statement for checking the temperature:

if [ "$ComparisonTemp" -gt "70" ]; then
   echo "Camera Pi Running Hot" | mail -s "Warning! The Camera Pi is Running Hot!!!" user@domain.tld
fi

Giving a final script that looks like this:

MyDate="`date +'%m/%d/%Y, %H:%M, '`"
MyTemp="`/opt/vc/bin/vcgencmd measure_temp |tr -d "=temp'C"`"
echo "$MyDate$MyTemp" >> /home/pi/Documents/python_projects/temperature/temp.log
ComparisonTemp=$(($(cat /sys/class/thermal/thermal_zone0/temp)/1000))

if [ "$ComparisonTemp" -gt "70" ]; then
   echo "Camera Pi Running Hot" | mail -s "Warning! The Camera Pi is Running Hot!!!" user@domain.tld
fi
Categories
Programming

Fizz Buzz

I was listening to the most recent episode of ATP and John Siracusa mentioned a programmer test called fizz buzz that I hadn’t heard of before.

I decided that I’d give it a shot when I got home using Python and Bash, just to see if I could (I was sure I could, but you know, wanted to make sure).

Sure enough, with a bit of googling to remember some syntax fo Python, and learn some syntax for bash, I had two stupid little programs for fizz buzz.

Python

def main():

	my_number = input("Enter a number: ")
	
	if not my_number.isdigit():
		return
	else:
		my_number = int(my_number)
		if my_number%3 == 0 and my_number%15!=0:
			print("fizz")
		elif my_number%5 == 0 and my_number%15!=0:
			print("buzz")
		elif my_number%15 == 0:
			print("fizz buzz")		
		else:
			print(my_number)


if __name__ == '__main__':
    main()

Bash

#! /bin/bash

echo "Enter a Number: " 

read my_number

re='^[+-]?[0-9]+$'
if ! [[ $my_number =~ $re ]] ; then
   echo "error: Not a number" >&2; exit 1
fi

if ! ((my_number % 3)) && ((my_number % 15)); then
	echo "fizz"
elif ! ((my_number % 5)) && ((my_number % 15)); then
	echo "buzz"
elif ! ((my_number % 15)) ; then
	echo "fizz buzz"
else
	echo my_number
fi

And because if it isn’t in GitHub it didn’t happen, I committed it to my fizz-buzz repo.

I figure it might be kind of neat to write it in as many languages as I can, you know … for when I’m bored.

Categories
Technology

Using MP4Box to concatenate many .h264 files into one MP4 file: revisited

In my last post I wrote out the steps that I was going to use to turn a ton of .h264 files into one mp4 file with the use of MP4Box.

Before outlining my steps I said, “The method below works but I’m sure that there is a better way to do it.”

Shortly after posting that I decided to find that better way. Turns out, it wasn’t really that much more work it was much harder than originally thought.

The command below is a single line and it will create a text file (com.txt) and then execute it as a bash script:

(echo '#!/bin/sh'; for i in *.h264; do if [ "$i" -eq 1 ]; then echo -n " -add $i"; else echo -n " -cat $i"; fi; done; echo -n " hummingbird.mp4") > /Desktop/com.txt | chmod +x /Desktop/com.txt | ~/Desktop/com.txt

(echo '#!/bin/sh'; echo -n "MP4Box"; array=($(ls *.h264)); for index in ${!array[@]}; do if [ "$index" -eq 1 ]; then echo -n " -add ${array[index]}"; else echo -n " -cat ${array[index]}"; fi; done; echo -n " hummingbird.mp4") > com.txt | chmod +x com.txt

Next you execute the script with

./com.txt

OK, but what is it doing? The parentheses surround a set of echo commands that output to com.txt. I’m using a for loop with an if statement. The reason I can’t do a straight for loop is because the first h264 file used in MP4Box needs to have the -add flag while all of the others need the -cat flag.

Once the file is output to the com.txt file (on the Desktop) I pipe it to the chmod +x command to change it’s mode to make it executable.

Finally, I pipe that to a command to run the file ~/Desktop/com.txt

I was pretty stoked when I figured it out and was able to get it to run.

The next step will be to use it for the hundreds of h264 files that will be output from my hummingbird camera that I just installed today.

I’ll have a post on that in the next couple of days.

Categories
Raspberry Pi

Using MP4Box to concatenate many .h264 files into one MP4 file

The general form of the concatenate command for MP4Box is:

MP4Box -add <filename>.ext -cat <filename>.ext output.ext1

When you have more than a couple of output files, you’re going to want to automate that -cat part as much as possible because let’s face it, writing out that statement even more than a couple of times will get really old really fast.

The method below works but I’m sure that there is a better way to do it.

  1. echo out the command you want to run. In this case:

(echo -n "MP4Box "; for i in *.h264; do echo -n " -cat $i"; done; echo -n " hummingbird.mp4") >> com.txt

  1. Edit the file com.txt created in (1) so that you can change the first -cat to -add

vim com.txt

  1. While still in vim editing the com.txt file add the #!/bin/sh to the first line. When finished, exit vim2
  2. Change the mode of the file so it can run

chmod +x com.txt

  1. Run the file:

./com.txt

Why am I doing all of this? I have a Raspberry Pi with a Camera attachment and a motion sensor. I’d like to watch the hummingbirds that come to my hummingbird feeder with it for a day or two and get some sweet video. We’ll see how it goes.

  1. The -add will add the <filename> to the output file while the -cat will add any other files to the output file (all while not overwriting the output file so that the files all get streamed together).
  2. I’m sure there’s an xkcd comic about this, but I just can’t find it!