Introduction: SCRUM Monkey

Picture of SCRUM Monkey

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:

Step 1: Components & Scheme

Picture of Components & Scheme

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

Step 2: Python Script

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/

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

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.


AshM1 (author)2016-04-23

I love that you could deploy this across different locations if your scrum teams are remote working and everyone gets screamed at at once.

SteveMann (author)2016-02-04

Love it!

SCRUM can normally get boring but I love the playful element of the Monkey as a way of making it fun.

jeristair (author)2016-01-08

isn't the crontab command wrong? shouldn't it be

* * * 13 40 (whatever the rest of the command is)

nivini (author)jeristair2016-01-08

Actually, when I edited it the first time, I took the format from my CentOS 6.5 machine and that format is just like you say. It didn't work and I didn't understand what's wrong. Than I found the other format and it's working.
I guess some Linux distros use this format and other distros use the other one.
Anyway, on Debian Wheezy (my RPi distro), it's the format I wrote.

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