Usermod for ESP32C3 Super Mini OLED 72x40 #5335

doccaz · 2026-02-01T16:21:27Z

This is a usermod built against the 0.15.3 branch that adds support for the ESP32 C3 Super Mini version with a 0.42" 72x40 OLED screen.

I added a few configuration options and quality-of-life improvements if you're using one of these in your project:

display flipping
using the on-board bootloader button to toggle brightness
screen offsets (this display controller uses a 128x64 layout internally for a "floating" smaller 72x40 screen)
bootsplash screen with Akemi (I actually developed a new tool to help draw it: https://doccaz.github.io/pixel-matrix-studio/)
screen blanking timeout

Summary by CodeRabbit

New Features
- Added OLED 72x40 display support for WLED
- Adaptive dashboard showing current effect, brightness level, and system stats
- LED heartbeat indicator for network connectivity status
- Boot splash screen displaying network information
- Configurable sleep/idle timer with automatic display blanking
- Display customization options: orientation flip and coordinate offset adjustment

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coderabbitai · 2026-02-01T16:21:35Z

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softhack007 · 2026-02-01T21:20:22Z

@doccaz is there a special reason why you made your PR against the 0.15.x branch?

normally we expect PRs to be made against the main branch, see https://github.com/wled/WLED/tree/main?tab=contributing-ov-file#target-branch-for-pull-requests

softhack007 · 2026-02-01T21:21:48Z

usermods/OLED_72x40/UsermodOLED72x40.h

+    void setup() {
+      pinMode(LED_PIN, OUTPUT);
+      Wire.begin(OLED_SDA, OLED_SCL);
+      WiFi.setTxPower(WIFI_POWER_8_5dBm);


There are known issues with the WiFi in this board that can make it quite unuseable. But it doesn't happen on all environments, maybe this should be a configuration option, I guess.
Reference: https://www.youtube.com/watch?v=UHTdhCrSA3g

ah ok, actually its already an option, so you don't need to repeat that in your UM

WLED/wled00/wled.h

Lines 379 to 380 in 6b953d9

#if defined(LOLIN_WIFI_FIX) && (defined(CONFIG_IDF_TARGET_ESP32C3) || defined(CONFIG_IDF_TARGET_ESP32S2) || defined(CONFIG_IDF_TARGET_ESP32S3))

WLED_GLOBAL uint8_t txPower _INIT(WIFI_POWER_8_5dBm);

just add -DLOLIN_WIFI_FIX to your build flags.

softhack007 · 2026-02-01T21:22:22Z

usermods/OLED_72x40/UsermodOLED72x40.h

+  public:
+    void setup() {
+      pinMode(LED_PIN, OUTPUT);
+      Wire.begin(OLED_SDA, OLED_SCL);


this should not be necessary, if you use the usermod global I2C pins.

softhack007 · 2026-02-01T21:24:14Z

usermods/OLED_72x40/UsermodOLED72x40.h

+      if (displayOff && u8g2) { u8g2->setPowerSave(0); displayOff = false; }
+    }
+
+    bool handleButton(uint8_t b) {


this will react on all buttons defined in the LEDs setting page, is this what you want?

softhack007 · 2026-02-01T21:28:44Z

usermods/OLED_72x40/UsermodOLED72x40.h

+        else u8g2->print(cmDNS);
+
+        u8g2->sendBuffer();
+        delay(5000); 


Sorry, such a long delay in the usermod setup function is a no-go.
This will delay the main loop for 5 seconds. Please find a different way.

You're right. It was just for showing a silly "bootsplash", I'll think of some other way.

softhack007 · 2026-02-01T21:31:18Z

usermods/OLED_72x40/UsermodOLED72x40.h

+      }
+
+      // 3. DRAWING LOGIC (Bypassed if screen is blanked)
+      if (strip.isUpdating()) return;


this might stall your usermod completely if someone has lots of LEDs. better:
if (strip.isUpdating() && (millis() - lastUpdate < 100)) return;

Noted! Thanks for taking the time to review this so thoroughly. First time contributing to WLED.

softhack007 · 2026-02-01T21:39:14Z

usermods/OLED_72x40/UsermodOLED72x40.h

+
+  public:
+    void setup() {
+      pinMode(LED_PIN, OUTPUT);


please use pin manager to check if the pin is free before writing to it.

softhack007 · 2026-02-01T21:52:20Z

usermods/OLED_72x40/UsermodOLED72x40.h

+      // Apply the button pin 9 default logic
+      int pin = top[F("bootButtonPin")] | 9;
+      if (btnPin[0] == -1 || btnPin[0] != pin) {
+        btnPin[0] = pin;


usermods should not interfere with the button handling code in button.cpp.
Its OK to read from the global btnPin[] and buttonType[] arrays. However modifying these arrays "behind the back" of the WLED core invites trouble.

Edit: It might be better to just make the "button index" (from LEDs preferences) configurable in your UM settings, and leave the button handling (and de-bouncing) to the wled core. You'll still receive the handleButton(b) event, and you could simply compare if b is the configured button index.

coderabbitai

Actionable comments posted: 2

🤖 Fix all issues with AI agents

In `@usermods/OLED_72x40/UsermodOLED72x40.h`:
- Around line 199-229: The addToConfig() currently writes a literal 9 so UI
changes are never persisted; introduce a class member int bootButtonPin = 9 and
use that member in addToConfig() instead of the hardcoded 9, update
readFromConfig() to read into bootButtonPin (e.g. bootButtonPin =
top["bootButtonPin"] | 9) and then use bootButtonPin when assigning btnPin[0]
(instead of reading pin from config and not saving it back to the member),
ensuring the new member is declared in the UsermodOLED72x40 class so the value
is preserved across config read/write and used when initializing buttonType and
btnPin[0].
- Around line 159-163: The brightness graph code fills vValues[71] but the
drawing loop only iterates i < 71 so the newest sample at index 71 is never
rendered; update the render loop in the UsermodOLED72x40 (the block that calls
u8g2->drawLine with currentX/currentY and vValues[i]) to include index 71 (e.g.,
iterate i < 72 or i <= 71) so vValues[71] is drawn, keeping the existing shift
logic (for (int i = 0; i < 71; i++) vValues[i] = vValues[i+1]) and the
assignment vValues[71] = map(bri, 0, 255, 0, 15).

🧹 Nitpick comments (1)

usermods/OLED_72x40/UsermodOLED72x40.h (1)
213-216: Avoid re-hardcoding default offsets in config load.

This duplicates defaults and risks drift if defaults change later.
♻️ Suggested cleanup
-      xOff = top[F("x-offset")] | 28; 
-      yOff = top[F("y-offset")] | 24;
+      xOff = top[F("x-offset")] | xOff; 
+      yOff = top[F("y-offset")] | yOff;
Based on learnings: In WLED code reviews, when code is modified or added, look for "magic numbers" (hardcoded numeric literals) and suggest replacing them with appropriate defined constants when those constants are meaningful in the context of the PR.

coderabbitai · 2026-02-01T22:05:11Z

usermods/OLED_72x40/UsermodOLED72x40.h

+          for (int i = 0; i < 71; i++) vValues[i] = vValues[i+1];
+          vValues[71] = map(bri, 0, 255, 0, 15);
+          for (int i = 0; i < 71; i++) {
+              u8g2->drawLine(currentX + i, currentY + 26, currentX + i, currentY + 26 - vValues[i]);
+          }


⚠️ Potential issue | 🟡 Minor

Brightness graph drops the newest sample.

vValues[71] is populated but never rendered.

🐛 Proposed fix

- for (int i = 0; i < 71; i++) { + for (int i = 0; i < 72; i++) { u8g2->drawLine(currentX + i, currentY + 26, currentX + i, currentY + 26 - vValues[i]); }

🤖 Prompt for AI Agents

In `@usermods/OLED_72x40/UsermodOLED72x40.h` around lines 159 - 163, The brightness graph code fills vValues[71] but the drawing loop only iterates i < 71 so the newest sample at index 71 is never rendered; update the render loop in the UsermodOLED72x40 (the block that calls u8g2->drawLine with currentX/currentY and vValues[i]) to include index 71 (e.g., iterate i < 72 or i <= 71) so vValues[71] is drawn, keeping the existing shift logic (for (int i = 0; i < 71; i++) vValues[i] = vValues[i+1]) and the assignment vValues[71] = map(bri, 0, 255, 0, 15).

coderabbitai · 2026-02-01T22:05:11Z

usermods/OLED_72x40/UsermodOLED72x40.h

+    void addToConfig(JsonObject& root) {
+      JsonObject top = root.createNestedObject(F("OLED_72x40"));
+      top[F("enabled")] = enabled;
+      top[F("flipDisplay")] = flipDisplay; // Registration for UI
+      top["bootButtonPin"] = 9;
+      top["x-offset"] = xOff;
+      top["y-offset"] = yOff;
+      top["sleepTimeout"] = screenTimeoutMS / 1000;
+    }
+
+   bool readFromConfig(JsonObject& root) {
+      JsonObject top = root[F("OLED_72x40")];
+      if (top.isNull()) return false;
+
+      enabled = top[F("enabled")] | enabled;
+      flipDisplay = top[F("flipDisplay")] | flipDisplay;
+      xOff = top[F("x-offset")] | 28; 
+      yOff = top[F("y-offset")] | 24;
+
+      // Guard against 0 or negative timeout values
+      unsigned long timeoutSec = top[F("sleepTimeout")] | 60;
+      screenTimeoutMS = timeoutSec * 1000;
+
+      if (initDone && u8g2) u8g2->setFlipMode(flipDisplay ? 1 : 0);
+
+      // Apply the button pin 9 default logic
+      int pin = top[F("bootButtonPin")] | 9;
+      if (btnPin[0] == -1 || btnPin[0] != pin) {
+        btnPin[0] = pin;
+        buttonType[0] = BTN_TYPE_PUSH;
+      }


⚠️ Potential issue | 🟠 Major

bootButtonPin setting is never persisted.

addToConfig() always writes 9, so UI changes are lost on save.

🛠️ Proposed fix

- top["bootButtonPin"] = 9; + top["bootButtonPin"] = bootButtonPin; @@ - int pin = top[F("bootButtonPin")] | 9; - if (btnPin[0] == -1 || btnPin[0] != pin) { - btnPin[0] = pin; + bootButtonPin = top[F("bootButtonPin")] | bootButtonPin; + if (btnPin[0] == -1 || btnPin[0] != bootButtonPin) { + btnPin[0] = bootButtonPin; buttonType[0] = BTN_TYPE_PUSH; }

// Add alongside other member fields int bootButtonPin = 9;

🤖 Prompt for AI Agents

In `@usermods/OLED_72x40/UsermodOLED72x40.h` around lines 199 - 229, The addToConfig() currently writes a literal 9 so UI changes are never persisted; introduce a class member int bootButtonPin = 9 and use that member in addToConfig() instead of the hardcoded 9, update readFromConfig() to read into bootButtonPin (e.g. bootButtonPin = top["bootButtonPin"] | 9) and then use bootButtonPin when assigning btnPin[0] (instead of reading pin from config and not saving it back to the member), ensuring the new member is declared in the UsermodOLED72x40 class so the value is preserved across config read/write and used when initializing buttonType and btnPin[0].

doccaz · 2026-02-02T13:16:30Z

@doccaz is there a special reason why you made your PR against the 0.15.x branch?

normally we expect PRs to be made against the main branch, see https://github.com/wled/WLED/tree/main?tab=contributing-ov-file#target-branch-for-pull-requests

Sorry, no particular reason at all. It was just the branch I had locally while testing this code. I'll work the changes for the main branch.

doccaz added 5 commits January 30, 2026 18:19

first working version

2fce12e

working version with Akemi logo and default button assignment

87a5bc1

FlipDisplay now working for dashboard and bootsplash!

b4c517b

removing extra file

8376587

Adding README

d805f8e

softhack007 reviewed Feb 1, 2026

View reviewed changes

coderabbitai bot reviewed Feb 1, 2026

View reviewed changes

softhack007 added usermod usermod related rebase needed This PR needs to be re-based to the current development branch labels Feb 1, 2026

	#if defined(LOLIN_WIFI_FIX) && (defined(CONFIG_IDF_TARGET_ESP32C3) \|\| defined(CONFIG_IDF_TARGET_ESP32S2) \|\| defined(CONFIG_IDF_TARGET_ESP32S3))
	WLED_GLOBAL uint8_t txPower _INIT(WIFI_POWER_8_5dBm);

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Usermod for ESP32C3 Super Mini OLED 72x40 #5335

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Usermod for ESP32C3 Super Mini OLED 72x40 #5335

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