initial commit

2026-07-11 14:54:56 -04:00
commit 23f714f570
15 changed files with 633 additions and 0 deletions
@@ -0,0 +1,33 @@
+---
+title: "Lilac's Website"
+description: "Computer Engineer & [Certified Punk Rocker](https://youtu.be/z9LiPuVRyU8&t=261)"
+---
+# About Me
+
+Howdy! My name is Lilac, and this is my website. I am interested in low-level
+computing, networking, and Linux. When not tinkering with 'puters, I birdwatch,
+crochet, and garden.
+
+# Technology
+
+I write embedded firmware and POSIX/Linux applications using C and several
+dialects of assembly. I do the server administration for all my own web services
+using Linux and Nix.
+
+Here is some of the software I've written:
+
+[Tanager](https://code.grasswren.net/Lilac/Tanager)
+: QMK keyboard firmware with flashy backlighting
+
+[grasswren.net](https://code.grasswren.net/Lilac/grasswren.net)
+: Content and Hugo theme for this website
+
+# Music
+
+My favourite genres of music are grunge, punk, hyperpop, breakcore, and digital
+hardcore. I really enjoy the music scene where I live; I think everybody should
+get out there and interact with their local artists.
+
+I self-host my music library, so I don't have opportunities to discover new
+music very often. If you are visiting this site for the first time, [shoot me an
+email](mailto:lilac@grasswren.net) telling me what I should listen to next!
@@ -0,0 +1,4 @@
+---
+title: Lilac's Birds
+description: They're cute little guys, aren't they?
+---
@@ -0,0 +1,4 @@
+---
+title: "Lilac's Blog"
+description: "I love pretending I know what's going on!"
+---
@@ -0,0 +1,154 @@
+---
+title: "Building Custom Keyboard Backlighting"
+description: "Upgrading my [Ergodox EZ](https://ergodox-ez.com/) using [QMK](https://github.com/qmk/qmk_firmware)"
+date: 2026-07-09
+---
+# Intro
+
+I own an Ergodox EZ, a very comfortable, split, columnar keyboard. I bought it
+because I gave myself carpal tunnel typing on my last keyboard, and I wanted to
+see if I could type any faster on a split board.[^1] Ergodox keyboards run
+open-source QMK firmware, meaning they are extensively configurable for a
+programmer like me! I love my keyboard, and I would recommend a split keyboard
+to anybody looking for something more comfortable than a standard keyboard.
+
+# Key Layout
+
+My key layout isn't the main focus of this post, but I wanted to highlight it
+because it uses some cool features QMK offers.
+
+![Keyboard Layout](/qmk/layout.png)
+
+The first thing to notice is that I have plenty of thumb keys for common
+keycodes. I never really liked that common keys like Enter, Backspace, and
+Escape[^2] were off to the side, so I moved them to be more easily accessible.
+
+On the bottom left side, there is a key labelled Layer. QMK has a concept called
+[layers](https://docs.qmk.fm/feature_layers), not unlike how a phone keyboard
+works: tap or hold a layer key, and access different keys. I use this for my
+function keys because I use them so infrequently, and I don't want them wasting
+space normally.
+
+Finally, I have a key labelled Macro. I commonly type `->` when programming, so
+I made this key type both characters in a single stroke. I also modified the
+handling of the Backspace key so it deletes both characters if the previous
+keycode was Macro.
+
+# Backlighting
+
+All the default backlighting options provided by QMK are too boring for me, so I
+rolled my own. It works like this, with each keyboard half operating
+independently:
+
+- Every keystroke changes the backlight colour
+- When all keys are released, the backlight LEDs fade out nicely
+- Backlight LEDs closer to the most recently pressed key are brighter than
+  those further from it
+
+Every time a keystroke is detected, the following function runs, tracking which
+key was pressed and updating the colours:
+
+```c
+void post_process_record_user(uint16_t keycode, keyrecord_t *record)
+{
+    if (!backlight || !record->event.pressed) {
+        return;
+    }
+
+    if (record->event.key.row < 7) {
+        hue_left = rand();
+        brightness_left = 255;
+
+        if (record->event.key.col != 5) {
+            position_left = 29 - 2 * record->event.key.row;
+        } else {
+            position_left = 15;
+        }
+
+        color(hue_left, brightness_left, position_left, 15);
+    } else {
+        hue_right = rand();
+        brightness_right = 255;
+
+        if (record->event.key.col != 5) {
+            position_right = 26 - 2 * record->event.key.row;
+        } else {
+            position_right = 14;
+        }
+
+        color(hue_right, brightness_right, position_right, 0);
+    }
+}
+```
+
+This function is rather long because I have to control the keyboard halves
+independently, but the main idea is simple. Every keystroke:
+
+- Randomize the colour hue
+- Maximize the brightness
+- Record the column the key is in
+- Turn on the LEDs using those values
+
+In another function, I keep track of how many keys are pressed at any given
+time, so I can dim the LEDs once no more are pressed:
+
+```c
+if (record->event.key.row < 7) {
+	count_left += record->event.pressed ? 1 : -1;
+} else {
+	count_right += record->event.pressed ? 1 : -1;
+}
+```
+
+## Brightness Calculation
+
+Now that I track these values, I need to use them to calculate the brightness of
+each LED:
+
+```c
+static void color(uint8_t hue, uint8_t brightness, uint8_t position,
+		uint8_t index)
+{
+    for (int i = index; i < (index + 15); ++i) {
+		const uint32_t cube = (uint32_t)brightness * brightness * brightness;
+		const uint8_t distance = position > i ? position - i : i - position;
+		sethsv(hue, 255, cube / 65025 * 5 / (5 + distance), i);
+    }
+    rgblight_set();
+}
+```
+
+This function takes in a hue, brightness, position, and starting index. There
+are 30 LEDs on an Ergodox EZ, meaning that I can pass either `0` or `15` as the
+starting index to have the function loop over the right or left LEDs
+respectively.
+
+The `brightness` and `position` parameters contribute to the brightness of the
+LED. First, the brightness is passed through a cubic ease-out function. This
+produces a more pleasing dimming as opposed to linearly dimming the LED, as the
+human eye senses brightness on a logarithmic scale. Second, the brightness is
+scaled down by an amount proportional to its distance from the last key pressed.
+The scaling function being used is `5 / (5 + n)` where `n` is the distance in
+LED index from the brightest LED, which is not dimmed because its scaling
+fraction evaluates to `1`.
+
+The `sethsv` function can then be passed a hue (given as a parameter and
+unchanging as the LED is dimmed), a saturation (always the maximum), the value
+(or brightness, as just calculated), and the index of the LED. Finally, I flush
+my LED settings out to the LED peripheral with the `rgblight_set` function.
+
+# Result
+
+With a little logic, the backlights on each keyboard half act just as I wanted,
+lighting up reactively and fading when no more keys are pressed.
+
+Take a look!
+
+![Typing on the Keyboard](/qmk/keyboard.mp4)
+
+# Footnotes
+
+[^1]: Quite a bit!
+
+[^2]: I use the [Helix](https://helix-editor.com/) editor, meaning I type
+      Escape almost as much as I type Space.