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.

Shifting the Smile - Freeing up some ports on AgoBo

This week I finally got around to setting up the code for the shift register I soldered onto AgoBo's 
prototyping board several months ago.

I used one of the preset positions for chips so it was relatively easy to add the board and some resistors to keep everything safe.

The seven segment display was then reconnected to the outputs and the head scratching began. I had a good look at the data sheet to get everything connected up then tried to sort out some test code to get the smile back on AgoBo's face.

I put some quick code making a short library so that i could call on mouth.smile in my code for AgoBo. I could probably make the code more efficient but this was a quick first attempt. I will try and get the code uploaded to my Git Hub repository when I have a chance to connect up AgoBo to the network

I have also added a talking mouth pattern to the different expressions that I may use if add some sound later on.

My next plan is to use some of the now free GPIO pins to light up some fibre optics I was given by my wife to make some hair. The current plan is to have the hair change colour to suit AgoBo's current emotions but some cycling also seems an appealing idea.

Acting the Part - A lesson in processor architecture

Part of the syllabus for my A-level computing group (OCR A Level) is to learn about and understand the make up of a CPU. This goes beyond the basic "this is the brains of a computer" and starts to look at how the CPU does it's job and which parts of the CPU do each part of the job.

To do this I could have done a 'chalk and talk' lesson telling the students all about the functions but I felt they would learn better if i could get them more involved. I also wanted to get them interacting and working together.

I did a lesson before with my Home Education group based on a CS unplugged activity - class simulation of a computer. I had adapted the ideas on the page to make a human calculator program using children to move the information around the parts of the computer. this was a little basic but it seemed like a good basis to expand on for my lesson.

As this was an A-Level group I wanted to get the students to do the thinking. So i came up with a plan based on a simple introduction to the parts and functions then set the students the task of designing activities to explain the working of the CPU to their classmates.

For the introduction we did a revision of the fetch-execute cycle and then went smaller to look at the parts of the CPU and what part they play in the process. The students were also given access to a YouTube playlist of videos about processor architecture to help them research the topic.

The students were split into small groups then set the task to design an activity to explain the process to their peers.

The Groups came up with a variety of ways of delivering the idea. All of the groups had an activity which showed they understood the process. The best group came up with an activity that involved the other students to take the role of each of the components and memory.

Their activity is detailed below (with a little editing):

Equipment:
Pens
Plain paper
Whiteboard pens
Mini Whiteboards
Labels for each of the components (can be written on the boards)

Set up:
1) Write a simple program to be used by the simulated computer the students used the following program:

     1 Load 70
     2 Add 71
     3 Store 72
     (at location 70 they had 712, at location 71 they had 73)

2) Select students to take the following roles -

     Registers:
     Program control - PC
     Memory Address Register - MAR
     Memory Data Register - MDR
     Current Instruction Register - CIR

     Arithmetic Logic Unit - ALU
     Control Unit - CU
     Accumulator - AC

     Cache Memory

     Address Bus
     Data Bus
     Control Bus

3) Hand each student the correct label, a whiteboard whiteboard pen, paper, and pen then position them around the classroom. Ensure the registers are together and the other components are spaced out around the room.

4) Hand Memory the Program and data loaded into memory


Activity

The students then act the parts of the CPU to carry out the program. To pass data / instructions / control around they write the information on to paper screw it into a ball and throw it to the next part in the process.

So for this example program the following happens:

1) PC is set at 1. This is transferred to the MAR (by throwing paper).
2) CU requests contents of address 1 from memory. (throwing paper via the address bus)
3) The data in the memory (LOAD 71) at address 1 is transferred to the MDR (via the data bus)
4) Contents of MDR loaded into the CIR
5) Contents of CIR sent to CU to be decoded (Data bus)
6) CU decodes the instruction and sends the required address to the MDR and increments the PC. (control bus)
7) Control signal sent (control bus) to fetch the data at the new address (70) (address bus)
8) Data from memory address 70  (712 ) loaded into the MDR (via the data bus)
9) Data from MDR (712) sent to the AC as required by the Load command


10......

this continues carrying out each instruction from the program so for this program PC 2 loads the Add 72 command which fetches the data from location 72 (73) and adds it to the AC. To add the two numbers the ALU is used. The total is added to the AC then the next instruction followed which in this case stores the result at memory location 72.



This could also be extended to show the extra time required to fetch data / instruction from RAM if they are not in cache memory. To do this the RAM should be positioned further away than cache memory. The cache is checked first then the RAM queried if it is not there.

The PiCycle an amazing student project

I have had the pleasure this year to have been a supervisor for one of our sixth form students doing an Extended Project Qualification (EPQ).

The EPQ is a level 3 qualification (similar to A-level) for students to do something that they are interested in. This can be an essay or an artifact and can take a myriad of forms. In this case my student chose to do a Raspberry Pi based project which was how I became involved.

Dan had no previous experience of the Raspberry Pi or Python before starting the project. He had done some web development but wanted to try something new. He spent a large portion of the project time mastering the basics of Python and the basic hardware before moving on to getting the project up and running.

The result is the PiCycle a Raspberry Pi based cycle computer that takes the position of the rider an plots it on a map on a website. The idea was to use the device to prove the designer had completed a planned charity cycle ride across France but could be used for all sorts of tracking applications. As well as getting the device working he spent some time getting it to look good too with branded interfaces on the device and the web tracking page.

The student developed the program to collect the GPS position and store this in a file on the Raspberry Pi and then upload the data to the web to display the position(s). The design means that whilst the cyclist is in areas of poor phone reception they can still log the GPS position (assuming GPS signal) and then upload the data when the phone signal is regained.

This project was a great achievement especially considering that Dan had no prior knowledge of the Raspberry Pi or Python before he started the EPQ.

Some more information about the project can be found in his project presentation. He can be found on twitter: @DJWOOLFALL.

Sci Fi Your Pi a design Challenge from Element14

After my success in the Raspberry Pi Educators Roadtest winning the prize for the UK (an Up mini 3D printer) I thought I would put in a proposal for their latest design challenge.

The title of the design challenge is "Sci Fi Your Pi" and centres around the idea of creating objects from or inspired by Science Fiction. This video explains what it is all about

I struggled initially to think of anything interesting being stuck on the suggestions made in the introduction to the challenge. However it was my search for difference that gave me the idea of looking at creating a Steampunk inspired device.

The kit for the challenge comes with a GPS model so this along with the strong adventurer spirit in Steampunk fiction I ended up with the idea of a Navigation device.

My idea has been selected from a large number of applicants among a very interesting group of projects. So far I have outlined my initial inspiration and described what I am hoping to produce for the challenge.  I have received the kit and I am putting together a plan of how I am going to make it work.

For anyone not familiar with Steampunk this video gives a fairly good introduction through a number of film clips. 

The spirit of adventure and exploration (as exemplified by the work of HG Wells and Joules Verne) felt like a great basis for a project where I will be trying new things and creating something a bit different to some of my other projects.

You can follow my progress on the Element 14 community with the tag steampunk_navigation. 

The Sound of Music - Sonic Pi with The Home Ed Computing Group

With the last session I had discovered the difficulty of the volume of text required when using python and the CamJam Edukits for some of the younger children. I have been working on a python library to help with this but this week i decided to use a different tool to look at coding concepts.

Sonic Pi is a great tool because it allows you to teach coding and make music at the same time. It was also a good way of being able to progress in complexity with computing concepts (introducing iteration) but keeping the level of text entry required to a minimum.

Sonic Pi is freely available software as part of the standard Raspian build and is also available for other platforms (more information here on the Sonic Pi Website)

The simple nature of the commands required for the children to be able to make music means it is a really good tool for younger (or children less able to read / type).

Some of the barriers I had found in the Python session had been easily overcome by the simple nature of the commands. I think would have struggled with getting some of the children to start looping blocks of code in Python yet they were all happily making repeating tunes with Sonic Pi. I really wanted to avoid simplifying things too much and this has provided a great bridge between the simple block programming that some of the children have done before and text based languages.

Sonic Pi itself is based on Ruby so it teaching a specific code structure and language that will continue to be useful. O so it is simplified in that the tasks it is performing are much more complex than the Play and sleep combinations, but it is a really engaging and relevant way to work with code.

I have written lots before about Sonic Pi so i will try and avoid this becoming the Sonic Pi fan page. However in reducing the volume of typing required I have found another way in which Sonic Pi makes coding accessible to a wider audience.

The group seemed to really enjoy this session and it was one of the most requested areas to do more with.

I am starting to look to move away from just leading the sessions and i already have several children with ideas for their own projects. This is an idea I am really keen to explore as i feel the best way to learn about computing is by finding challenges and solving them using computing. If children can find something that interests them they are much more motivated to explore than if they are being directed by someone else.

Getting Physical with Python

This session with my HomeEd group I introduced some physical computing using the CamJam Edu kit .

Last time I blogged about the challenge of teaching a group with my own children (who are not used to a classroom environment). This week I had the additional challenge of my normal child swap falling through so I ended up with 3 of my own children to contend with.

With this in mind my plan was for more independent work with some supporting materials to make it easier for the children to work without my direction all of the time.

I also planned to manage the situation by placing my offspring carefully either side of me in the room so I could switch between the instruction and paying them attention. This worked much better for me to be able to manage the session. Although at one stage it did mean carrying 2 of my children whilst trying to explain things on the board (using my daughter to point out the relevant bits whilst I talked).

I had decided that I did not want to over simplify things for the children by using scratch. We had also been mainly working at the command line so it made sense to progress with this and use nano to create python files to control the components. This also followed the CamJam worksheets so I could use those to provide additional guidance so the children could refer back to the instructions.

As the group is very mixed (5-15) there was a range of experience in the group but most had not used electrical components in a breadboard before. After a quick introduction they were all setting up the simple LED and resistor circuits.

Most of the group managed to get as far as getting the lights lit but it did take some time to get there. The real limiting factor I found with using python with the younger children was the speed they were able to type the code was very slow compared to the older students (as they are still working on their reading skills this is actually quite a hard task).

There was no apparent problem understanding the concepts and adding text to control things, but the amount of text that needed reading and adding to the code was a problem. To make it easier for these younger students (and any students who find reading / typing difficult) it would be useful to reduce the volume of typing that is required to produce a result.

That said nearly all of the children had at least lit the LEDs by the end of the session even if this had involved a bit of help with typing from the adults in the room.