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and writer Sean McManus

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Using the PiCube on Raspberry Pi

23 February 2018

I recently had a chance to play with the PiCube, a 3D grid of 64 LEDs that you can control using the Raspberry Pi's 40 GPIO pins. It's a clever design based on multiplexing that makes this possible, but the compromise is that you can't individually control each light. All the layers that are switched on show the same lights. It's of limited use for games, then, but could be great for creating visual effects. If you're building a large robot, you could make its pulsing "heart" using PiCube (although not in a heart shape). I'm reminded of KITT's voice box in Knight Rider.

In education, it provides a highly visual way to explore nested loops and nested lists. It's also a good way to drill your soldering skills, since it comes in kit form.

You can read my review of it in issue 67 of The MagPi, which has just been published. It's available for free download, but you can support the Raspberry Pi Foundation by buying it, on the high street or by subscription.

Here's a video showing the PiCube in action:

And here's the code I wrote for that demo. PiCube comes with some demo programs, but the pin numbers were arranged in a linear list in them. I found it easier to work my way around the grid when I created a nested list for the pins, which I've called GRID_3D here.

#! /usr/bin/python
import RPi.GPIO as GPIO
import time


LAYER = [40,38,36,32]

GRID_3D = [[7, 11, 35, 37],
     [12, 13, 31, 33],
     [15, 16, 23, 29],
     [18, 19, 21, 22]

def enable_layer(layer):
    GPIO.output(LAYER[layer], True)

def disable_layer(layer):
    GPIO.output(LAYER[layer], False)

def light_on(y, x, z):
    GPIO.output(GRID_3D[x][z], True)    

def light_off(y, x, z):
    GPIO.output(GRID_3D[x][z], False)

def reset():
    for x in range(4):
        for z in range(4):
            GPIO.output(GRID_3D[x][z], False)
def resetlayer():
    for i in range(0,4):

for pin in LAYER:
    GPIO.setup(pin, GPIO.OUT)

for x in range(4):
    for z in range(4):
        GPIO.setup(GRID_3D[x][z], GPIO.OUT)

# Display each light in turn
for y in range(4):
    for x in range(4):
        for z in range(4):
            light_on(y, x, z)
            light_off(y, x, z)

#Turn on all the lights
for y in range(4):
for x in range(4):
    for z in range(4):
        light_on(y, x, z)

PiCube is available now from SB Components.

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Cool Scratch Projects gets a cool 5* review!

04 February 2018

My book Cool Scratch Projects In Easy Steps has received a fantastic 5* review in the latest issue of The MagPi magazine!

The reviewer writes: “Here’s a book that lives up to its title -- these are some cool scratch projects... If you got a Pi and a book for Christmas, this will make a great follow-on. Recommended.”

The reviewer loved that some of the games are programmed in 3D, and that each book comes with its own pair of 3D glasses and has an easy first project so you can get stuck in straight away.

You can read the review for yourself below and in issue 66 of The MagPi, available to download for free from The MagPi website. Alternatively, why not support the Raspberry Pi Foundation by subscribing to the print edition, or picking a copy up from your local newsagent or bookstore?

Review from The MagPi of Cool Scratch Projects in Easy Steps

Cool Scratch Projects in Easy Steps is out now. Find out more and download a free PDF sampler here, which includes the Magic Mirror project mentioned in the review. You can also watch a video previewing all the projects below.

Many thanks to The MagPi for the review!

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Brighton Science Festival: Join a Coder Academy this February

29 January 2018

Book cover: Coder Academy I’ve been invited to the Brighton Science Festival on Monday 12 February, where I’ll be hosting a number of Coder Academy workshops. They are practical coding sessions for 7-10 year olds, tying in with my latest book (also called Coder Academy) which is published by Brighton-based publisher Ivy Kids.

You don’t need any previous experience of coding, just an interest and desire to know more. We’ll be learning snippets of the Scratch programming language and using them to experiment with digital art. The ticket includes a copy of the Coder Academy book, and I’ll be very happy to sign copies on the day!

Interested in coming along? Places are limited so register as soon as you can. And why not set yourself up with an account on the Scratch website before you come? It means you’ll be able to save your projects to share or work on later.

You can see the full programme for Brighton Science Festival here (10-18 February 2018, Brighton, various venues). Thank you to the organisers and the team at Ivy Kids for making this happen. I'm looking forward to seeing what the participants create!

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Discover how to use a Raspberry Pi to make new sounds for the Yamaha DX7 synthesizer

10 January 2018

The current issue of The MagPi includes a feature I wrote about Midimutant, a Raspberry Pi project for programming the Yamaha DX7 synthesizer. The DX7 was popular in the 80s, but was hard to create new sounds (or patches) for. Richard James, who records as Aphex Twin among other aliases, suggested that there must be a more interesting way to program an FM synthesizer and his friend Dave Griffiths took up the challenge. Using a Yamaha TX7 (which is like the DX7 but without a keyboard), he made a Raspberry Pi project that randomly generates sounds and then mutates them until they come close to a particular target sound.

picture of the 2-page spread in The MagPi

The project is broadly applicable, because it doesn't need to understand how the synth works: it just needs to be able to create random data for it to play back, and then listens to the result.

"It's actually most interesting when it doesn't quite work," says Dave. "Discovering that some cymbals were all evolving to silence as the background hiss from the TX7's 12 bit processor was considered a close enough match, was an 'aha' moment - these types of evolutionary algorithm have a tendency to surprise you like that."

Richard says he will be using the results on his tracks whenever possible, so you might well hear Midimutant's results before too long.

To find out more, check out issue 65 of The MagPi. It's in shops now, and it's available for free download too. While you're there, you can also pick up MagPi issue 64, which includes my report on Pycon.

(If you're interested in the Raspberry Pi, check out the new, updated third edition of Raspberry Pi For Dummies here too.)

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Video: The St Ives Lifeboat coming in

08 January 2018

We were in St Ives over the holiday period and had a chance to see the St Ives Lifeboat, RNLB Nora Stachura (RNLI 13-11) on exercises at sea, and coming in to land.

I had my pocket camera on me, and took the opportunity to take some photos and record some video clips, which I have edited together into the short film shown below. I was a bit late realising I could make a video of this, so there's one sequence of the boat and the tractor joining which I would ideally have captured on video, but I have bridged that using a series of photos. I found that some of the clips required a cross-fade because their composition was too similar and it jarred when I just cut between them. The whole process took about an hour, but I've edited this film down to about three minutes.

This was an enjoyable exercise in photography and film editing, and I hope captures the spirit of the experience. It was wonderful to see the lifeboat and its dedicated crew at work.

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Adding gesture control to the Raspberry Pi with Flick

27 November 2017

Flick, from Pi Supply, is a series of add-ons for the Raspberry Pi that you can use to detect taps, touches and finger movements. There are three devices in the series:

The Flick HAT for Raspberry Pi Zero, shown mounted on the Pi Zero

The board can be used to detect touches, taps and double taps. The ability to detect taps in five positions (north, south, east, west, centre) means it can be used as a simple five-button interface. It can also detect airwheel gestures (spinning your finger above the board) and the finger position above the board, including height. In my experience, the device can detect heights of up to about 7cm or 8cm above the board. Height detection still works through the case (there's a set of cases available to compliment the device), although the contact gestures (tap and touch) don't work when the device is in the case.

The Flick can also be used to detect flick gestures (hence the name!), swiping across the board from top to bottom or left to right (or in the other directions). This seems to work at a slightly lower height than the maximum height for finger position detection, based on my setup.

There are lots of potential applications for the Flick. The swiping gesture lends itself well to scrolling through options, and the airwheel could be used as a control for volume or similar parameters. The Pi Zero form factor could be used to make a remote control for a robot or other device. The first thing anyone thinks of is probably a theremin, but that remains a cool project and the Flick could be a nice way to add one discreetly to an existing object. Robot projects could use Flick to add the ability to detect touch. One of the endearing things about the commercial Pepper robot is that it responds when you stroke its head, and that kind of feature could be easily implemented using the Flick.

The most promising format is the Flick Large, because it could give you greater freedom for expressive movements, and so open up new creative possibilities. There's lots of potential in creating robot control panels by putting a decorated sheet of paper in front of the Flick Large, indicating where the virtual controls are for tapping or hovering over. If it works through your desk, the Flick Large could be used to add an invisible touch interface to your furniture. Pi Supply has thought of this and designed a case that enables it to be mounted under the desk in this way.

A Python API is in development, and this will be a big help. The flick-demo program is good for testing the Flick and provides some hackable code, but a few "hello world" examples and a documented API would make it more accessible and easier to build into projects. Here's my "hello world" program for position detection, based on stripping down the flick-demo program:

#!/usr/bin/env python

import flicklib
import time
import os

x_pos, y_pos, z_pos = 0, 0, 0

def move(x, y, z):
     global x_pos, y_pos, z_pos
     x_pos = x
     y_pos = y
     z_pos = z

while True:
     print("X:", x_pos)
     print("Y:", y_pos)
     print("Z:", z_pos)

If you're looking to add gesture controls to your projects, or are interested in innovative new interfaces, Flick can be a great addition to your Raspberry Pi. Find out more about the Flick family at the Pi Supply website here. Thanks to Aaron, Francesco and John at Pi Supply for their help with this review.

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How to Code shortlisted for Educational Writers' award

15 November 2017

Book cover: How to CodeI am delighted to say that my book Super Skills: How to Code has been shortlisted for the ALCS 2017 Educational Writers’ Award. The book was illustrated by Venitia Dean and published by QED Publishing/Quarto.

Each chapter covers a different super skill in coding, using Scratch to make interactive programs and HTML for website design. The book includes one of my favourite Scratch games of those I've created, a platform game called Treetop Catnap.

The judges said: "Providing a lively way into an exciting new subject for all age groups, this book approaches complex ideas with both humour, and beautiful clarity. Full of handy tips and easy-to-understand instructions, it succeeds in making coding a fun activity for both boys and girls."

The other shortlisted entries are:

The winner will be announced at the All Party Writers Group (APWG) Winter Reception at the House of Commons on Tuesday 5th December.

I'd like to thank the team at QED and illustrator Venitia Dean for all their great work on How to Code, and the judging panel and organisers for reviewing and shortlisting the book. You can find out more about How to Code here, and you can play Treetop Catnap below if you have a compatible browser (click flag to start; cursor keys move, space jumps):

[UPDATE: Congratulations to Piotr Socha, Wojciech Grajkowski and Agnes Monod-Gayraud on winning with The Book of Bees! Many thanks to ALCS, the Society of Authors and the APWG for a lovely evening on the Terrace at the House of Commons, and for shortlisting How to Code for the award.]

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Books by Sean McManus

Scratch Programming in 

Easy Steps

Scratch Programming in Easy Steps

Raspberry Pi For Dummies

Raspberry Pi For Dummies

Learn to program with the Scratch programming language, widely used in schools and colleges.

Set up your Pi, master Linux, learn Scratch and Python, and create your own electronics projects.

Coder Academy

Coder Academy

Cool Scratch Projects in Easy Steps

Cool Scratch Projects in Easy Steps

Learn to make games and other programs in Scratch 2.0, and make a web page in HTML, with this highly interactive book for 7-10 year olds.

Discover how to make 3D games, create mazes, build a drum machine, make a game with cartoon animals and more!

More books

©Sean McManus.