Introduction: SCRUM Monkey

By

In my workplace, we have a daily scrum meeting at exactly 13:40. Regardless to that, I have a small monkey toy which makes some monkey noises and blinks while pressing its right ear. I decided to turn it into an alarm by connecting it to my Raspberry Pi.

This monkey has it's own power supply (3.3v) so I had to use a darlington transistor (TIP120/121/122 family) for switching. Just take a look at the photos and scheme, it's a very simple circuit. To control the monkey with the RPi, I wrote a small and simple Python script which activated the alarm at 13:40 by using the good old Linux crontab program.

Here's a link to the video on Youtube:
https://www.youtube.com/watch?v=T6SphTKMWPM

Step 1: Components & Scheme



• TIP120 (or 121, 122)
• 1K ohm resistor


Step 2: Python Script

Attachments

Step 3: Crontab

On the Linux shell, type:

$ crontab -e

In the editor that has just been opened, type:

40 13 * * * /usr/bin/python /home/scrum_monkey.py

The format of crontab is:
1 2 3 4 5 command

where:
1 - Minute (0 - 59)
2 - Hour (0 - 23)
3 - Day of month (1 - 31)
4 - Month (1 - 12)
5 - Day of week (0 - 7)

There are some special characters you can use instead of the numeric values. For example asterisk (*) in hour means every hour. Read the manual. By the way, I've noticed that the format is a bit diffetent, depends on the Linux distro.