Visakha-Lamp

A 22-lamp light panel driven by an ESP32 and controlled from any phone. The ESP32 runs its own Wi-Fi access point and serves the control page itself, so there is no app, no router and no internet connection involved.

Hardware

Board	ESP32 Dev Module (developed on an ESP32-D0WD-V3, 4 MB flash)
LEDs	WS2812 / NeoPixel strip, 66 pixels — three per lamp
Data	GPIO 13 → strip DIN, through a 330 Ω resistor
Power	separate 5 V supply for the strip, ground shared with the ESP32

This branch drives the strip from the SPI peripheral instead of RMT: the data line must sit on GPIO 13, the SPI2 (HSPI) native IOMUX MOSI pin, which the driver routes through the IOMUX rather than the GPIO matrix. (SPI3's IOMUX MOSI is GPIO 23.) The main branch uses RMT on GPIO 4 instead, so the wire has to move when you switch branches.

Change NUM_GROUPS, LEDS_PER_GROUP or NUM_LEDS at the top of main/main.c if your panel is wired differently.

Using it

1. Power the panel. It starts a Wi-Fi access point using the credentials from .env — by default SSID Visakha Lamp, password 12345678.
2. Join it from a phone and open http://192.168.4.1/.
3. Tap a lamp to switch it. The Settings button at the bottom of the page holds the master brightness, the transitions, the animations, three colours, and each lamp's name.

Transitions and animations run on the real LEDs, not in the browser:

• Transitions — what a single lamp does when you switch it: None snaps, Fade glides (the default).
• Animations — what the whole panel does: Random star twinkles lamps at random, Chase sends a smooth glow up the panel, lighting one row at a time from the bottom.
• Colours — one triplet of colours for the whole panel, one per LED in a lamp, so every lamp always matches.
• Light the rest — fills in every lamp that is still dark, one per second, then waits out the hold (Start animation after, in seconds, default 15 minutes) and starts the chosen animation by itself. Pressing it again, tapping a lamp or All off stops it.

Brightness, transitions, animations, the hold, lamp names, the colours and the lamp states are saved in flash and come back after a power cut.

The panel is labelled in the order you see it, and a lamp map in the firmware translates those labels to the strip's wiring order, so the chase climbs the rows you actually have.

HTTP API

Request	Effect
GET /	the control page
GET /set?i=<lamp>&v=0|1	switch lamp i (0–14) off or on
GET /alloff	switch every lamp off
GET /brightness?v=<0-255>	master brightness
GET /transition?v=0|1	how a lamp switches: 0 none, 1 fade (default)
GET /animation?v=0|1|2	0 none, 1 random star, 2 chase, bottom row to top
GET /color?k=<0-2>&c=RRGGBB	colour of one LED of every lamp: slot 0, 1 or 2
GET /name?i=<lamp>&n=<text>	rename a switch (URL-encoded)
GET /state	JSON: on, names, colors, brightness, transition, animation, hold, wait, sequence
GET /hold?v=<seconds>	wait between the fill and the animation (default 900 = 15 min)
GET /reset	factory reset: clears every setting and lamp state

Lamp map

The panel is labelled 1–22 in the order you see it, but the strip was wired in a different order, so s_lamp_to_strip[] in main/main.c records which strip position each label sits at (lamp 1 → strip 10, lamp 2 → strip 11, lamp 3 → strip 9, …). Buttons, names, colours and the running light all work in label order; only the pixel output is translated, which is why the running light follows the labels rather than the wiring.

The firmware checks at boot that the table is a clean one-to-one mapping and logs an error if it is not.

Building

Requires ESP-IDF v6.1 (installed here with eim install).

Set the access point credentials first. .env is git-ignored, so the password never reaches the repository:

cp .env.example .env        # then edit AP_SSID and AP_PASS

Then build and flash:

source ~/.espressif/tools/activate_idf_v6.1.sh
idf.py set-target esp32
idf.py build
idf.py -p <PORT> flash monitor      # ls /dev/cu.* or /dev/ttyUSB* to find PORT

The top-level CMakeLists.txt reads .env while configuring, so changing it and running idf.py build again is enough — no other file needs touching. If .env is missing the build falls back to the defaults in that file.

Layout

main/main.c            firmware: soft AP, HTTP server, WS2812 output, transitions
main/page.h            generated: the control page as a C string
web/page.html          the control page itself, hand-editable (SVGs inlined)
tools/build_page.py    web/page.html -> main/page.h
.env.example           template for the Wi-Fi credentials (copy to .env)

To change the page, edit web/page.html, run python3 tools/build_page.py, then flash.

Switch names, colours and brightness are held in RAM and reset when the panel is unplugged; the switch states themselves start off.