GPIO Zero - making coding less language intensive.

In a previous post Getting Physical with Python I wrote about the difficulty some of the younger children in my computing group had with the volume of typing required to get started with physical computing. They did not struggle with understanding but it took too much time and help to enter the volume of text required. This took away some of the excitement and slowed things down.

At the time I thought to speed this up it would be good to write a python library to reduce the amount of text needed to get things to happen. Unfortunately I had lots of other things to do and this never went anywhere. However someone else also thought it would be good to make it easy to get started with physical computing and was able to do something about it.

That person was Ben Nuttall of the Raspberry Pi Foundation. Along with Martin O'Hanlon and Dave Jones he has created GPIO Zero. You can read his account of how it happened on his blog.

This python library can be used to very simply control components using the GPIO pins. The initial function set is based around the popular CamJam EduKits  (Kit 1- Starter, Kit 2 - Sensors) and makes a great starting point for physical computing using python.

A simple light and button combination can be controlled with the below example:

from gpiozero import LED, Button led = LED(15) button = Button(14) button.when_pressed = led.on button.when_released = led.off

instead of something like this:

import os 
import time  
import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BCM) 
GPIO.setwarnings(False) 


GPIO.setup(14, GPIO.IN)
GPIO.setup(15, GPIO.OUT) 

while True: 
        if GPIO.input(14) == False: 
              GPIO.output(15, HIGH)   
        else: 
               GPIO.output(15, LOW)  

 time.sleep(0.5) 

The reduction in volume of code and setup required is brilliant. GPIO Zero is an amazing tool for education. This is especially true where the volume of text entry is a barrier (either with younger or SEN children).

The tool allows the focus to be on the programming concepts and not on the entry of text. When i worked with my HomeEd computing group there was a difficulty fro a number of the students (aged between 5 and 15) in using the GPIO library as there was a lot of code to enter. They were generally happy with what they were trying to achieve but found that it took a long time to enter the lines of code required just to light up the LEDs.

This meant that in the one hour session that is what we achieved, lighting up the LEDs. Whilst this was a success and the children were happy with getting there it would have been much better to spend more of the time in the session exploring what could be done rather than entering lots of text.

GPIO Zero takes away some of the burden allowing children to focus on what they are trying to achieve rather than on copying out lots of lines of code (especially the set up parts that are conceptually more difficult to grasp and result in questions about what is BCM etc).

I have found that where I have used this it has meant I can more on more quickly and cover more of the computational thinking ideas where previously there would have been more time waiting for the students to catch up with the typing required. It also works well to satiate the desire for instant gratification that appears to be fairly common among my pupils. They only have to spend a short time entering code before they can see a result.

It is also much easier in a classroom to debug the code they have written if there are errors. The reduced volume of code makes for less searching to find the capitol that should't be there. This make students more able to do it themselves or makes it quicker for me when they can't see what is wrong. The reduction in time taken here give me the opportunity to get to more pupils and help them to progress.



I have also used this at home with my son (8) whilst he has been creating a robot using the CamJam EduKit 3 - Robots. This was really powerful because it allowed him to achieve results in short pockets of time before he lost focus and wanted to move on. He used the provided worksheets to set up the robot and connect the components and I translated the code parts into GPIO Zero for him to get the robot working.

So in summary the feedback is - Thanks Ben this is an awesome tool to help me teach computing.

If you are interested in using GPIO Zero there is a great getting started guide on the Raspberry Pi website in the resources 'Learn' Section.

More information can be found on pythonhosted.org or on GitHub. There is also a Google Doc with information and a place to add comments / requests.

Agobo The Hackable Raspberry Pi Robot - now with emotions

My wife gave me a 4Tronix AgoBo robot kit for Christmas (at my request). I built it a few weeks ago but didn't really have time to do anything with it.

The AgoBo is a Raspberry Pi A+ based robot kit. I also ordered the Plus plate that adds a Neopixel and lots of prototyping space on a board that mounts above the RPi. The kit is a really good affordable robot kit that can be customised very easily, especially with the PlusPlate. It is this customisation that really attracted me to the AgoBo in the first place.

When the robot arrived I thought that the Ultrasonic sensor looked like a pair of eyes but AgoBo was lacking a mouth. On another evening I was rooting through a box of electronic bits I bought for RPi projects and found an 8x8  LED matrix. 

I had seen plenty of robot that used these as eyes and thought that this could work. However with the robot being so small the matrix was far too large. I had another dig in the box and found a more suitably sized replacement.

The 5011AS display fitted just below the ultra sonic sensor with the pins above and below the main board. Aligned horizontally the segments could be used to make a smile or sad face by lighting the correct segments.

This idea was put on the back burner for a couple of weeks whilst normal life got in the way. and I kept thinking about how to mount the module effectively under the board. When I was able to experiment with the robot again (finally loaded the example software and tried out the supplied python scripts) I couldn't resist having a try with the mouth idea.

I haven't found time to solder the header on to the plus plate yet and wanted to get the mouth working so I grabbed a breadboard and some cables to try it out before I sorted it all out properly.

I had a ten cable female to female ribbon so I divided that into two (5 cables in each) to connect the ten pins of the display. With the ends of the cable connected there was very little room between the pins but with a little blue tack the display mounted nicely with two pins each side below the board and three above. To keep things tidy I separated the first part of the cable for a short length and then wrapped the cable up over RPi and under the PlusPlate (with a little Blue Tack of course).

I then grabbed a few resistors and connected the cables to the breadboard and then connected the other side to the header I fitted to the main board (in preparation for connecting the plus plate).

This is where I ran into my first problem.limited time and a failure to read instructions lead to an error in the connections. Instead of looking at the instructions I looked at the numbers on the top of the PlusPlate and reading down from the top started used the first available pins. Unfortunately these pins are already in use by AgoBo so there was a bit of a conflict when I tried to use these to run the mouth.

So looking back at the instructions I made a list of the pins that were in use and looked again at the PlusPlate for available pins and moved the connections to pins that were not already in use by AgoBo.

Once I had the connections all set up (correctly this time) I needed to set up- the code to run the mouth and control the facial expressions. I decided i wanted a smile (obviously, what's cuter than a smiling robot?) a sad face, a confused face and an open mouth, After this time consulting the instructions (the data sheet from Jameco) I drew a little diagram of which pin controlled which segments of the display and worked out a little table of which should be displayed for each facial expression.

With this organised I set up a Python library (mouth.py) to set up the facial expression and then a quick script to test the expressions. The test script (mouthtest.py) shows each expression I have set up so far. the smile, sad face and 'oh' i am really pleased with. I am not to sure about the confused face so I may not use that very much. These scripts will be available from my AgoBo Github fork here.

.

With the mouth working I wanted to work the expressions in to the normal running program for Agobo. I had written a quick script previously for him to avoid objects using the ultra sonic sensor so I used this as a starting point.

I ran into a small issue here as I had set up the mouth library using GPIO numbers and the AgoBo library is set up using board numbers. after a little head scratching (I am still unsure why in an error state the face always seems to display 'oh') I spotted the error and changed the mouth library to match the python library and now Agobo will avoid objects whilst displaying his emotions.

Currently he is happy moving forward until he finds an object. This makes him sad and he turns 90 degrees. If he can move forward he is happy again. If instead there is another object in his path he is shocked / cross ('oh') and turns 180 degrees. Again if the way he clear he is happy again and proceeds. However if there is another object he becomes confused (or his face does) and then turns 90 degrees (away from the initial object and proceeds on his way happy again.