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Jack Farley, Computer Engineer

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  • about

  • CSS is Awesome

    11/26/2024

    Ok. CSS is in an awesome place now. We have functionality, including CSS variables and functions like color-mix() that make writing CSS so compact. Here's what I mean.
    • css
    • software

  • Boolean Attributes in Custom Angular Components

    12/18/2023

    I like clean code so being able to have boolean attributes like required in my custom Angular components makes me happy. To do it however you need an extra bit of javascript.
    • angular
    • javascript
    • software
  • 12/18/2023

    Before I loose it again, one of the best references for creating accessible web sites is the ARIA Authoring Practices Guide (APG). It has good examples of how to create some complex components like navigation with submenus and treegrids, as well as best practices.

    • accessibility
    • software
  • 12/11/2022

    Please! Stop with the mobile web sites! If you are using browser agent strings to change your CSS/layout don't! Use responsive CSS instead. There are other situations when you need a small window and devices that have a small screen where your web site does not work.

    • software
    • web

  • Minimal Accessible Tooltip

    12/2/2022

    Doing a lot of web accessibility fixes, I wondered what would be the minimum amount of code to create a WCAG 2.1 compliant custom tooltip. Unfortunately, it had to include Javascript. Here is what I came up with.
    • software
    • web
    • a11y

  • Day-to-day with Librem 5

    11/28/2022

    After quite a few years of waiting, I finally got my Librem 5 phone. I am now using it as my primary phone… using my work phone as a back-up. Here are the issues and whether I think using it as a primary phone is a good idea so far.
    • librem5
  • 11/28/2022

    If you are wanting to apply accessibility labels onto an image, here are the label (alt, title, aria-description, aria-label) priorities (highest first): aria-description (with aria-label, alt or title); aria-label; alt. Note aria description does not get read out if there is no other label attributes. (Tested on Windows, NVDA, and Firefox and Edge).

    • software
    • web
    • a11y

  • Email dates in Javascript

    11/24/2022

    Javscript is missing functions to format dates in some common formats, such datetime-local inputs and RFC 5322 (email dates) in a non-obsolete way. While Date.toUTCString() is close, the timezone is now obsolete (though it is handy for HTTP Date and other such headers). Here's the basic functions to get the right formats
    • software
    • javascript

  • Visibility and CSS Accordians

    11/24/2022

    When changing a reworked menu to have accordian animations, I came to the realisation that I have been missing a big issue when using max-height transition animations — accessibility. I detail a simple fix in this article.
    • software
    • web
    • a11y
    • css
    • javacsript

  • Can't touch list

    11/24/2022

    Turns out screen readers really don't like you playing with the display CSS property on lists, for example to change it to an inline list — it will cause lists items to be read like a paragraph. Here's how to do without upsetting the screen readers.
    • a11y
    • software
    • css

  • New Zealand Low Power Networks (LTE-M & NB-IoT)

    10/14/2022

    I have started experimenting with low power wide area networks (LP-WAN) in New Zealand using a u-blox SARA-R410-02B. Here is what I have experimented with so far.
    • electronics
    • software

  • JS Binary Decoder

    10/11/2022

    I have recently been dealing with parsing binary data packets from various sources, and have published two NPM libraries from it: binary-decoder and sbd-direct-ip. Here's how they came to be.
    • software
    • javascript

  • Starting with ESP32

    2/7/2022

    I started developing my trap-watch project on an ESP32-CAM using the ESP IDF. Here is the newbie difficulties I ran into.

    The List

    Here is the list of newbie gotchas I ran into when developing the trap-watch project. I will be adding more gotchas as I find them so watch this space….

    Including Libraries like espvfsfat.h in Components

    To include library files like espvfatfat.h in components, you have to REQUIRE the correct component in your components CMakeLists.txt file. For example, for the Fat Filesystem, the component to require is fatfs. You can then #include "esp_vfs_fat.h" in your component file.

    Installing the right version of ESP-IDF

    By default, the esp-idf installation instructions tell you to install the latest version (read latest including unstable version). I think it is a good idea, especially when you are starting out to use the stable version. To install the stable version, find the current stable version (will be listed as stable in the version menu on the left of the ESP-IDF docs page) and change to that version before you install.

    # Clone the repository without initialising the submodules
git clone https://github.com/espressif/esp-idf.git
# Go into the directory
cd esp-idf
# Checkout the stable version
git checkout vX.X.X
# Initialise the submodules
git submodule update --init
# Install for an ESP32
./install.sh esp32

    The finicky ESP32-CAM SD card

    The SD card seems to be the most finicky thing on the ESP32-CAM board. Not helped by the fact that the high speed SPI port that the SD card is connected to has the flash LED and in my case the PIR sensor attached to it. I configured the SDMMC library to use a bus width of 1, but found that whenever I removed the power on the board, it would always fail to initialise the SD card.

    D (2901) sdmmc_periph: slot=1 host_div=10 card_div=20 freq=400kHz
D (2911) sdmmc_periph: slot=1 width=1
D (2911) sdmmc_req: process_command_response: error 0x107  (status=00000100)
D (2941) sdmmc_req: process_command_response: error 0x107  (status=00000100)
D (2941) sdmmc_sd: CMD8 timeout; not an SD v2.00 card
D (2941) sdmmc_req: process_command_response: error 0x107  (status=00000100)
D (2941) sdmmc_io: sdmmc_init_io: io_send_op_cond (1) returned 0x107; not IO card
D (2951) sdmmc_req: process_command_response: error 0x107  (status=00000100)
D (2961) sdmmc_req: process_command_response: error 0x107  (status=00000100)
D (2971) sdmmc_req: process_command_response: error 0x107  (status=00000100)
D (2971) sdmmc_cmd: sdmmc_send_cmd_send_op_cond: sdmmc_send_app_cmd err=0x107
D (2981) sdmmc_common: send_op_cond timeout, trying MMC
D (2991) sdmmc_req: process_command_response: error 0x107  (status=00000100)
D (2991) sdmmc_req: process_command_response: error 0x107  (status=00000100)
D (3001) sdmmc_req: process_command_response: error 0x107  (status=00000100)
D (3011) sdmmc_cmd: sdmmc_send_cmd_send_op_cond: sdmmc_send_app_cmd err=0x107
E (3011) sdmmc_common: sdmmc_init_ocr: send_op_cond (1) returned 0x107
D (3021) sdmmc_init: sdmmc_card_init: sdmmc_init_ocr returned 0x107
E (3031) vfs_fat_sdmmc: sdmmc_card_init failed (0x107).
E (3031) trap-watch: Got an error initialising SD card 0x107: ESP_ERR_TIMEOUT

    Not only that, but then trying to flash the ES32-CAM with an SD card inserted failed and blinded me by constantly flashing the flash. Only after setting the width back to 4, removing the card during flashing did it come right again. 

    D (2911) sdmmc_periph: slot=1 host_div=10 card_div=20 freq=400kHz
D (2921) sdmmc_periph: slot=1 width=1
D (2921) sdmmc_req: process_command_response: error 0x107  (status=00000100)
D (2951) sdmmc_sd: SDHC/SDXC card
D (2951) sdmmc_req: process_command_response: error 0x107  (status=00000100)
D (2951) sdmmc_io: sdmmc_init_io: io_send_op_cond (1) returned 0x107; not IO card
D (2981) sdmmc_common: host_ocr=0x40ff8000 card_ocr=0xc0ff8000
D (2981) sdmmc_common: sdmmc_card_init: host_ocr=40ff8000, card_ocr=c0ff8000
D (2981) sdmmc_init: sdmmc_card_init: card type is SD
D (2991) sdmmc_common: sdmmc_init_host_bus_width: using 4-bit bus
D (2991) sdmmc_periph: slot=1 width=4
D (2991) sdmmc_common: sdmmc_init_host_frequency: using 20000 kHz bus frequency
D (3001) sdmmc_periph: slot=1 host_div=8 card_div=0 freq=20000kHz
D (3011) vfs_fat_sdmmc: using pdrv=0
I (3021) SD Card: Filesystem mounted
Name: SU04G
Type: SDHC/SDXC
Speed: 20 MHz
Size: 3781MB

    I also had to then configure the Flash pin pulldown to turn the flash off.

    gpio_set_pull_mode(FLASH_PIN, GPIO_PULLDOWN_ONLY);

    mDNS domain

    When trying to access your ESP32 using mDNS, don't forget the .local domain name

    $ ping trap-watch.local
    • esp32
    • electronics
    • software
    • trap-watch

  • VIM Window Rabbit Hole

    2/4/2022

    Developing ESP-IDF components I thought it would be great if I could make a command to open all the files for a component at once. What a rabbit hole it was. Here is how I did it.
    • linux

  • Parsing Arguments in Bash

    1/28/2022

    Making a script parse arugments in Bash took me way too long last time I did it, so here is a nice full example of how to do it using getopt
    • linux

  • Where's my bait gone?

    1/8/2022

    I have recently started trapping some introduced predators around my local area and have had baits and pre-feed disappear with nothing to show for it, so I decided to get sparky and see if I could catch the culprit in the act.
    • electronics
    • conservation
    • trap-watch

  • Bathymetric Contours

    3/26/2021

    Finally got around to creating a SLD style for GeoServer to display bathymetric contour lines using the GEBCO gridded bathymetric data. Here's how.
    • gis
    • geoserver
    • oceans

  • shm That Cache

    2/25/2021

    I am often trying to find more space on my hard drives and found today my own docker containers wasting space thanks to ! Here's how I fixed it.
    • yarn
    • docker
    • development

  • Blob blob blob blob Stayin' Alive Stayin' Alive

    2/2/2021

    Upon recently trying Deezer again, I found their web app ate all my memory when running in Firefox, so I decided to see if I could find out why. I got as far as memory-file-data/string and Blobs. Here's how.
    • software
    • javascript
    • debugging
    • memory

  • A new Litter Survey

    12/25/2020

    In a culmination of litter surveys and litter picks, linked data and data exploration, and remoteStorage and ActivityPub, I have created a web-based litter pick/survey app that I hope will allow federated citizen science.
    • software
    • litter
    • litter-survey

  • Hoe Stream Trash

    12/14/2020

    My latest litter pick target was Hoe Stream and the White Rose Lane Local Nature Reserve. Here's how it went.
    • litter
    • pi-trash-cam
    • litter-pick
    • environment

  • Release the Beast

    11/24/2020

    I just created a Gitlab CI job to create a release with information from a CHANGELOG.md file for some of my projects. Here's how I did it.
    • software
    • gitlab
    • ci
    • release

  • Gitlab CI Caching

    9/30/2020

    I noticed something strange happening during build process during a multi-tasking bug fix. Turns out I was using Gitlab CI's caching incorrectly. I should have been using artifacts. Here's what I saw.
    • gitlab
    • continuous integration

  • Birthday Trash

    9/22/2020

    As a birthday treat, I took the day off work to try out my electronerised litter picker. Here's how it went.
    • litter
    • pi-trash-cam
    • environment

  • Pi Trash Cam

    9/13/2020

    In preparation for a day of litter picking, I finally got round to a project idea - attaching a camera to a litter picker to record it all. Here's what I did.
    • raspberry pi
    • electronics
    • litter
    • pi-trash-cam
    • environment

  • yarn add --dev webdriverio

    8/25/2020

    I finally started implementing UI testing on first-draft using WebdriverIO. While writing tests was easy, getting the tests running was a little more difficult. Here is how I did it.
    • first-draft
    • software
    • testing
    • gitlab
  • 8/16/2020

    Hooray! My new blog is live! Based on Sapper, using MongoDB and eventually ActivityPub and ActivityStreams, it will be my federated posting hub to the world.

    • software
    • blog

  • Removing EXIF Data from Photos

    8/9/2020

    Creating this new blog, I wanted to make sure there was no metadata data leaking personal information. Here's how I removed all the metadata tags except the ones I wanted from my photos.
    • exif
    • photos

  • tmux List and Reattach

    8/9/2020

    Using tmux for your terminal multiplexer but want an easy to reattach to a session? Here's a small bash script to do it.
    • tmux
    • bash
    • software

  • Selectable Shell Examples

    8/8/2020

    Here's how to help your readers save time by making your post's shell commands easy to select and copy - with a simple CSS property.
    • markdown
    • syntax
    • css

  • Be Dates You

    8/5/2020

    Making my new blog, I didn't initially set the published dates to be native dates in the database. Here what I did to change them …and do all the upgrades I needed.
    • mongodb
    • docker

  • Testing vue components

    7/8/2020

    I recently needed to test that some Vue components were creating the correct HTML. To do this, I decided to create snapshots of Object representations of the rendered HTML.
    • software
    • vue
    • testing
    • javascript

  • No More Numbers

    2/20/2019

    HTML5 number inputs aren't useful, but tel inputs, have all the power
    • javascript
    • html5
    • software

  • A Hacker "Hacked" Me

    12/21/2018

    I decided to look into the extortion emails I have been getting and wrote a small script to extract the bitcoin addresses that have been used.
    • security
    • email
    • grep

  • Mouse Surgery

    12/7/2018

    As part of my pledge not to upgrade, I decided to repair two of my failing mice instead of replacing them with a brand new model (as tempting as it was). Here's what I did.
    • pledge to not upgrade
    • electronics

  • Danger Danger, Highly Reactive

    10/29/2018
    • vue
    • reactive
    • graphing
    • data

  • Switching to SSR

    9/11/2018
    • react
    • ssr
    • react-loader

  • Clean Docker Registry

    8/10/2018
    • node
    • docker
    • console
    • javascript

  • Testing on the Filesystem

    2/1/2018
    • testing
    • javascript

  • Tag You Are

    1/26/2018
    • javascript
    • tags

  • NaN Got Me

    1/25/2018
    • rubber duck save
    • javascript
    • nodejs
    • json

  • All our app's tabs are belong to us

    4/28/2017
    • angular
    • javascript
    • localstorage
    • rxjs
    • sessionstorage

  • Developing NPM modules

    2/20/2016
    • nodejs
    • npm

  • Nfa + Nfb or N(f+fa+fb)

    2/20/2016
    • array
    • function
    • javascript
    • jsperf

  • Photo Layout

    10/31/2015
    • arranger
    • css
    • gallery hierarchy
    • html
    • javascript
    • photos
    • tinymce
    • wordpress
    • software

  • Browning Pass HideAway Web Site

    10/31/2015
    • css
    • gallery hierarchy
    • html
    • wordpress

  • Think Mobile

    10/17/2015
    • mobile
    • web

  • Pledge to Refuse and Not Buy Bottled Water

    10/13/2015
    • environment
    • pledges

  • Run PHP run!

    2/25/2015
    • maximum execution time
    • php
    • trial and error

  • Gallery Hierarchy

    11/26/2014
    • gallery
    • hierarchy
    • photos

  • Vim and functions

    10/3/2014
    • function
    • navigation
    • tags
    • vim

  • I'm making hierarchies

    9/26/2014
    • hierarchical data
    • hierarchy
    • php

  • Google Sheets fun

    9/4/2014
    • google
    • google script
    • google sheets
    • javascript
    • sheets

  • Travel Photos

    8/13/2014
    • photo management
    • photos
    • travel photos

  • Image managment scripts

    8/13/2014
    • photo management
    • photos

  • MeldCE logo

    7/31/2014
    • css
    • html5
    • javascript
    • svg

  • MoltenDB

    4/26/2014
    • database
    • moltendb
    • mongodb
    • nodejs

  • The Expensive Side

    10/29/2013
    • house

  • abcde

    9/22/2013
    • music

  • Energizer Power Plus Rechargeable Batteries

    7/16/2013
    • gadgets

  • USAR FOGTeX

    3/4/2013
    • fogtex

  • Personal Gear Bag

    2/21/2013
    • rescue
    • gear

  • Geocaching Stamp

    2/18/2013
    • stamp
    • geocaching

  • Call Record Presenter

    4/2/2007
    • parser
    • python
    • sqlite
    • web

  • Kimi Ora School

    9/25/2004
    • css
    • html

  • All About Catering Web Site

    6/25/2004
    • css
    • html

  • Quantum Accounting Web Site

    7/26/2003
    • css
    • html
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