Here's how to set the time on the badge. There's a hardware clock which should keep time between reboots.

1. Install mpremote on your computer.
2. Connect the Tildagon to your computer using a USB-C data cable
3. On your computer's command line, run mpremote. You should see: > Connected to MicroPython at /dev/ttyACM0 > Use Ctrl-] or Ctrl-x to exit this shell
4. Hold down the ctrl key on your computer. While holding it down, press the C key on your computer. This will open up a shell for you to enter commands.
5. Enter the following commands one at a time, followed by enter

from machine import RTC
rtc = RTC()
rtc.datetime()

That will display the time that the badge currently thinks it is.

For example: (2000, 1, 1, 5, 0, 1, 47, 984022)

This is a slightly unusual format. It is: year, month, day, weekday, hours, minutes, seconds, subseconds.

The "weekday" is 0 for Monday, 1 for Tuesday etc.

This is an array. So, to access individual elements of the time, you can say:

year = rtc.datetime()[0]

Alternatively, you can do:

import time
time.localtime()

That will return something like: (2024, 6, 11, 15, 11, 39, 1, 163)

Which, according to the documentation, is "year, month, mday, hour, minute, second, weekday, yearday".

Setting the clock

To manually set the date and time, run:

rtc.datetime((2023, 6, 16, 1, 15, 36, 0, 0))

NTP

If you want to use NTP to synchronise the time with an Internet-based atomic clock, here's what you need to do.

1. Connect your badge to WiFi.
2. As above, connect with USB and run mpremote, then obtain a shell.
3. Enter the following commands one at a time, followed by enter:

import ntptime
ntptime.settime()
rtc.datetime()

That will now show you the synchronised time. Note, it will be set to UTC. There's no way to set the timezone - you'll have to deal with that in your code elsewhere.

You can also read the reference documentation about the Real Time Clock.

Here's the end result:

Background

I'm going to assume that you have updated your badge to the latest firmware version.

You will also need to install mpremote on your development machine.

You should also have successfully run the basic Hello, World! app.

Drawing surface

The Tildagon screen is 240x240 pixels. However, it is also a circle. This gives an internal square of 170x170 pixels. The drawing co-ordinates have 0,0 in the centre. Which means the target area is the red square as shown here:

Generate a QR code

As you can see, there isn't much space here. A Version 1 QR Code is a mere 21x21 pixels. When set to "Low" error correction, it can contain up to 25 characters. A URl should start with https:// - which is 8 characters. That leaves 17 characters for the domain and path.

Use your favourite QR generator to make the tiniest QR code you can. Make sure there's no border. It should be 21x21 pixels. Here's mine:

See? Tiny!

Prepare the QR code

Next, we need to turn the QR code into a binary matrix. There may be easier ways to do this, but I used a scrap of Python:

from PIL import Image
import numpy as np

#    Load the image
image = Image.open("qr.png")

#    Convert the image to grayscale
gray_image = image.convert("L")

#    Threshold the image to get binary black and white image
threshold = 128
bw_image = gray_image.point(lambda x: 0 if x > threshold else 1, '1')

#    Convert the image to a NumPy array
pixel_array = np.array(bw_image, dtype=int)

#    Convert the array to a string with commas between the elements
array_str = np.array2string(pixel_array, separator=',', formatter={'int':lambda x: str(x)})

print(array_str)

Copy the output - we'll need it later!

Calculate size

We have a canvas of 170 pixels and a QR code of 21 pixels. 170 / 21 = 8.1 pixels. Ah. Drawing fractional pixels isn't fun. Luckily, QR codes benefit from having a safe area around them. If we make each QR pixel 7 screen pixels, that gives us (21 x 7) = 147 pixels. Which gives us enough space for a small white border.

If the QR code is to be centred, the top left corner will be in position (147 / 2) = 74. That means it will need to be drawn at position -74,-74. The top left corner is -120,-120.

So the offset used to calculate the location is (-120 + 74) = 46.

(You might be able to get away with 8 pixels and an offset of 36 pixel. Try it!)

Remember those numbers!

Write the app

This reuses a lot of the Hello World code.

import app
from app_components import TextDialog, clear_background
from events.input import Buttons, BUTTON_TYPES

class QrApp(app.App):
    #   Define the colours
    black = (  0,   0,   0)
    white = (255, 255, 255)

    def __init__(self):
        self.button_states = Buttons(self)

    def update(self, delta):
        if self.button_states.get(BUTTON_TYPES["CANCEL"]):
            self.button_states.clear()
            self.minimise()

    def draw(self, ctx):
        clear_background(ctx)

        #   QR code data (21x21 matrix)
        qr_code =[[1,1,1,1,1,1,1,0,0,1,1,0,0,0,1,1,1,1,1,1,1],
                  [1,0,0,0,0,0,1,0,1,0,1,0,0,0,1,0,0,0,0,0,1],
                  [1,0,1,1,1,0,1,0,1,1,1,1,1,0,1,0,1,1,1,0,1],
                  [1,0,1,1,1,0,1,0,0,1,1,0,0,0,1,0,1,1,1,0,1],
                  [1,0,1,1,1,0,1,0,1,1,1,1,0,0,1,0,1,1,1,0,1],
                  [1,0,0,0,0,0,1,0,1,1,0,1,0,0,1,0,0,0,0,0,1],
                  [1,1,1,1,1,1,1,0,1,0,1,0,1,0,1,1,1,1,1,1,1],
                  [0,0,0,0,0,0,0,0,1,1,1,1,1,0,0,0,0,0,0,0,0],
                  [1,1,0,1,0,0,1,1,0,0,1,0,0,0,1,1,1,0,1,1,0],
                  [1,0,1,1,1,1,0,1,1,0,0,1,1,0,1,1,1,0,0,0,1],
                  [1,0,1,0,0,1,1,1,0,1,1,0,1,0,0,0,0,0,1,0,1],
                  [1,1,1,1,0,1,0,1,0,0,0,0,0,0,1,0,1,1,0,1,1],
                  [1,0,1,0,0,1,1,1,0,0,1,1,1,0,0,1,0,1,0,0,0],
                  [0,0,0,0,0,0,0,0,1,0,0,0,1,1,0,1,0,0,0,0,1],
                  [1,1,1,1,1,1,1,0,1,0,1,0,1,1,0,0,1,1,1,1,0],
                  [1,0,0,0,0,0,1,0,0,0,0,1,1,0,0,1,1,0,0,0,0],
                  [1,0,1,1,1,0,1,0,0,0,1,1,0,1,0,0,1,1,0,1,1],
                  [1,0,1,1,1,0,1,0,1,0,0,0,1,0,1,0,1,0,0,0,1],
                  [1,0,1,1,1,0,1,0,0,0,1,1,1,0,1,0,1,0,1,0,1],
                  [1,0,0,0,0,0,1,0,1,1,1,0,0,1,0,0,0,0,0,0,0],
                  [1,1,1,1,1,1,1,0,1,0,1,0,1,0,1,0,1,0,0,1,0]]

        #   Draw background
        ctx.rgb(*self.white).rectangle(-120, -120, 240, 240).fill()

        #   Size of each QR code pixel on the canvas
        pixel_size = 7

        #   Offset size in pixels
        offset_size = 46

        #   Calculate the offset to start drawing the QR code (centre it within the available space)
        offset = -120 + offset_size

        #   Loop through the array
        for row in range(21):
            for col in range(21):
                if qr_code[row][col] == 1:
                    x = (col * pixel_size) + offset
                    y = (row * pixel_size) + offset
                    ctx.rgb(*self.black).rectangle(x, y, pixel_size, pixel_size).fill()

__app_export__ = QrApp

Installation

• Follow the instructions
• Run mpremote cp ~/Documents/badge/* :/apps/qr/
• Restart the badge
• Scroll down the app list and launch the QR app

The non-stupid way!

OK, that was the hard way - here's the easy way.

Use the MicroPython QR Generation library uQR.

If you pop that file in your project directory, and upload it to the badge, then you can import it with:

from .uQR import QRCode

The QR code has its own white margin and is a 2D array of True & Falses.

# QR code data (29x29 matrix)
qr = QRCode()
qr.add_data("https://edent.tel")
qr_code = qr.get_matrix()
qr_size = len( qr_code )

#   Draw background
ctx.rgb(*self.white).rectangle(-120, -120, 240, 240).fill()

#   Size of each QR code pixel on the canvas
pixel_size = int( 170 / qr_size ) + 1

#   Border size in pixels
border_size = ( 240 - (pixel_size*qr_size) ) / 2

#   Calculate the offset to start drawing the QR code (centre it within the available space)
offset = -120 + border_size

#   Loop through the array
for row in range( len(qr_code) ):
    for col in range( len(qr_code) ):
        if qr_code[row][col] == True:
            x = (col * pixel_size) + offset
            y = (row * pixel_size) + offset
            ctx.rgb(*self.black).rectangle(x, y, pixel_size, pixel_size).fill()

Next steps

• This is hardcoded for a single QR code - mine! Perhaps it should be configurable?
• Add some text to the screen?
• Animations? Colour? Flashing LEDs?

Got any thoughts? Stick them in the box!

So I was beyond thrilled to be able to attend & speak this year.

There's always a risk that you can never recapture the magic of your youth. But EMF is consistently brilliant. A delightful alternative reality of robots, lasers, art, lasers, music, lasers, technical talks, lasers, and strange lights in the sky.

Also, a TESLA COIL!

All the talks I went to were brilliant. Most of the talks I missed were also brilliant and I'm enjoying watching the catch-up streams. I took loads of silly photos, sat under an inverted fire pit, and talked to hundreds of lovely people. Oh, and watched my brilliant wife be Thor - the host of lightning talks.

I volunteered a couple of times (which was a rewarding experience) and got some meal vouchers for my troubles. Result! All the volunteers seemed to be having a whale of a time. Great seeing people pull together to make something special.

There was decent WiFi all over the field. I don't get the appeal of DECT phones - but they were ubiquitous.

Even the toilets were great! Seriously, it felt like luxury for a festival.

There was far too much to do. I didn't even try any of the CTF games or puzzles, I managed to play one arcade machine (plus a laser-projected Asteroids game), and only sampled a few of the beers available. My petition is to make EMF a 2 week festival in order to allow me to enjoy all of it 😄

Bug Reports

All the bugs from my previous visit had been squashed. Presenters were all made to do laptop checks before presenting. There were no airhorns or howling in the middle of the night. Food stalls were relatively quick. All the Q&A happened away from the main stage. And diversity was much improved.

But, what is life if not full of the joys of complaining? Treat these kvetches as minor irritants.

• P4 - I went to a workshop which wasn't well designed. Despite being advertised for beginners, the instructor seemed bemused and annoyed that people were asking for help with the basics.
• P3 - The Night Market was a bit cramped. Half a dozen vendors in a single shipping container made it hard to browse and chat. While commerce isn't the primary aim of the festival, it would have been nice to have more space to view all the wares.
• P3 - Official communications were a bit fragmented. There was Mastodon, and Signal groups, and Matrix/IRC, and probably more that I missed. It's great to have a variety of channels - but it was slightly overwhelming trying to check them all.
• P2 - Stage B had a pillar in front of the centre of the stage, which made it a bit awkward to see what was going on sometimes.
• P1 - The bar ran out of cider on the last night!!!! OK, it was pretty impressive that we collectively drank the bar dry 😂
• P1 - The badges...

*sigh* I feel bad about ragging on the badges. They're high-tech gizmos obviously made with love. But if you're selling a gadget, I think it is reasonable for people to expect it to work. As in previous years, badges weren't generally available until later in the festival. When I did get mine, it just didn't work. The software crashed trying to update itself and the promised app store also didn't work. I don't think I saw anyone using it to display their name.

I know that the logistics of shipping hardware and getting software working is a difficult process. And I saw the team working flat-out to resolve the issues. The badge tent was full of helpful people and other attendees were willing to share tips. But I can't help feeling that these teething issues should have been solved a few weeks before launch.

Ah well, I'm sure it'll all be working by 2026!

Verdict

I made a small tactical error by camping near to Null Sector. Surprisingly, I was able to sleep through the bone-rattling Drum and/or Bass. I suppose walking for miles in a field will do that! Even so, I came back from EMF feeling like my brain had been energised and my creativity had been given a super-boost.

I don't think I want to give a talk at the next one - I loved the experience, but it's time for more new faces. Instead - I want to see if I can build something delightfully delirious. Perhaps a multi-player collaborative game? Well, I've got two years to get it ready!

First up… sewage! Festivals often have big tanks to take away human effluence. But how can you, a normal human, tell how full they are? Luckily, fresh sewage is warm.

Phone boxen were plenty - thanks CuTel. Because the metal of the box is cold and human fingers are warm, it's possible to see recently dialled numbers.

While there was lots of solar power on site, sometimes you need a thwacking big diesel generator! Here's an IR video of it in action.

Got a datacentre in a portable toilet? No need to open the doors!

Perhaps you will have people cooking on a barbecue. Is it warm enough to safely cook food?

Or, Scottish people might start deep-frying Buckfast (this genuinely happened!)

After all that, time for a nice cold beer.

Cheers!

You can view more thermal images on Mastodon

Photograph © Skylar MacDonald 2022. All Rights Reserved. The moral rights of the author have been asserted.

The universe, of course, had other plans. Striking down both Liz and me with COVID literally the day before we were due to pick up our camper. FUCK YOU UNIVERSE. FUCK YOU COVID!

Thankfully, our symptoms weren't too bad (thanks to some TOP SECRET medical experiments we may or may not be participating in. Shhhh!)

And, even more thankfully, Jonty and his crew of joyful nerds found a way for me to do my presentation. There's this brand new technology called "Zoom". I really think it could be even bigger than ICQ messenger because - get this! - you can send voice and video and slides at the same time. MAGIC!

So I hastily rejigged my slides, gulped down some industrial-strength cough medicine, and said hello to all my new friends.

I asked the tech team to mount my laptop so I could see the smiling faces of anyone who'd entered the tent. It almost worked.

It's always hard presenting to a room where you can't hear people chuckling at your jokes. It's worse when you can't even tell if they're humans or poorly constructed animatronics. But I got a little bit of audience participation going and, overall, it went pretty well, I think:

The wonders of technology! Despite catching Covid, @edent was still able to give his talk about solar panels #EMFCamp

Dan Pope

Dale Lane (inactive)

@dalelane

such a shame I didn’t get to see @edent in person, but even over video call his #emfcamp talk was a fun, geeky dive into solar power at home
emfcamp.org/schedule/2022/… pic.x.com/2au0elao5k

---

Really enjoying @edent's Solar Punks Assemble talk at #emfcamp2022 - lots of knowledge and lovely graphs!

Aidan Taylor

John Hegarty

@johnhegs

Replying to @edent@edent @klkl @emffilmfest Really enjoyed the talk. Gonna get some quotes in for solar panels now !

---

Loving @edent’s enthusiasm for solar @emfcamp - great spreading of the word!

Steve Pike

Harvinder Atwal (totally not on mastadon)

@harvy2004

After a late night (3:30am at the arcades) #emfcamp today is a slow start. First talk I went to was cancelled but got an impromptu talk on ADHD instead. Now onto solar panel data.

---

Harvinder Atwal (totally not on mastadon)

@harvy2004

Replying to @harvy2004pic.x.com/j94u87xacj

---

ada

@Ada Rose Cannon

We thought your EMF talk was really good. Our building collective is thinking about putting solar panels on the roof of here.

---

Sadly, it looks like official videos might not appear this year:

Electromagnetic Field

@emfcamp

Talk recordings will be delayed this year, and it's possible some talks may not have been recorded.

We'll provide updates as soon as we know more.

---

But... Because I love you all very much, I did a pre-record just in case the live-stream failed. My brain and throat were slightly addled with Covid when I did the record - so I ask you to bare that in mind. You can watch it for free at:

If you'd like me to natter on about solar in person - buy me a pint first ☺

Welcome to ElectroMagnetic Field!

(I've stolen the subtitle from Ken MacLeod's description of Charles Stross's story Dechlorinating the Moderator.)

I'm not one for camping. Or doing anything in a field. So I was quite nervous about attending the festival. But everyone was lovely, the talks were amazing, and the food was good.

At every turn I bumped into people doing amazing things. Robots! LIDAR! Science! It was blissful. And the cider was pretty cheap.

I've never been to a laser powered rave watched over by a robot cat, while people covered in LEDs danced under posters promoting genetic modification on the BlockChain. I've never sat in a tent while watching a material scientist demonstrate her craft - and then later gone back to the same tent to watch a Chap Hop singer strut his stuff.

EMF is weird!

Bug Reports

These are all P3 or lower.

• As a sleeper, I don't want to be woken up in the middle of the night by air-horns. I'm quite happy for "bangin' chooons" to pump out - but my ear-plugs are not designed to cope with klaxons being fired off.
• As an audience member, I don't want to watch 20 minutes of a presenter figuring out how to connect a laptop to a projector. All presenters should have to use the pre-configured stage laptop. I only saw one talk which needed a specialist laptop - to show the audience a view from a USB camera.
• As someone who eats food, I don't want to queue for 30 minutes only to be told the advertised vegetarian breakfast isn't available. This is a problem unique to UK food-trucks. They seem taken by surprise that customers want to give them money. A few of the trucks were excellent, and knew how to serve food quickly. Still, an excellent range of veggie food.
• As someone who wants to ask a question at a talk, I don't want to be stuck behind someone saying "Less of a question, more of a comment." These people need to learn some manners!
• As a wishy-washy-bleeding-heart-politically-correct-do-gooder, I'd like to have seen more diversity. There was no lack of age or gender diversity, but it all felt a bit white.

Highlights

We accidentally hired a very silly campervan. Which lead to...

Terence Eden is on Mastodon

@edent

Taking photos of people taking photos of our campervan 😂
#EMFcamp pic.x.com/xexknx7pf3

---

clairementine

@claz0r

Replying to @edent@edent Yup #emfcamp pic.x.com/24ccoymoew

---

I did my talk about The (Connected) House of Horrors and loads of people came!

Terence Eden is on Mastodon

@edent

Put your hands up if you agree to my privacy policy!
#EMFcamp pic.x.com/3xzzixoip2

---

Christian Payne

@Documentally

That’s @edent rocking a massive crowd at #EMFcamp talking hacking hearts and the lack of security in teledildonics. #IoT pic.x.com/ycgrvk0qaz

---

My brilliant wife did a talk about our OpenBenches project.

I met so many new people, reconnected with old friends, and put faces to Twitter avatars. I had my mind expanded about LGBTQ+ behaviour in animals, saw people hacking their way through insurmountable technical obstacles, and was inspired by all the beauty and creativity on show.

Roll on EMF 2020!