Update README for version 6.2.4 release

Updated version number to 6.2.4 and added highlights for the new version, including a critical bug fix related to display refresh at exact hour boundaries.

CHANGELOG.md

@@ -2,6 +2,93 @@
 
 All notable changes to this project are documented here.
 
+## v6.2.4 - Exact-boundary display refresh bug (2026-04-01):
+
+**Summary**
+
+Top of the hour auto display refresh glitch fix where display automatically refreshed but showed the PREVIOUS hour's data.
+
+### Problem: 
+- At the exact top of the hour (e.g., 20:00:00), the display automatically refreshed but showed the PREVIOUS hour's data (19:00). This happened because the "next-boundary" rounding logic in findCurrentPriceIndex() incorrectly excluded the current interval if the time was exactly on the boundary.
+
+### Solution: 
+- Simplified findCurrentPriceIndex() to use a robust "last entry <= now" comparison. This ensures the display transitions to the new hour instantaneously at XX:00:00.
+
+---
+
+## v6.2.3 - State-based display refresh logic fix (2026-04-01):
+
+**Summary**
+
+The refresh logic should be "State-Based" rather than "Event-Based." Instead of checking if the minute is zero, it should check if the current hour is different from the last recorded hour.
+
+### Problem: Screen would occasionally fail to update if the ESP32 was busy 
+   - fetching data or reconnecting WiFi) during the exact 00/15/30/45 minute mark.
+
+### Solution: Switched from "Event-Based" (refresh only AT minute X) to "State-Based" 
+    
+    (refresh IF current time != last refresh time). 
+  - This ensures the screen updates immediately even if the device was busy during the transition.
+
+---
+
+## v6.2.2 - Display blank lines issue fix (2026-03-31):
+
+**Summary**
+
+Fixed a bug where the display was showing blank lines
+
+### Problem: Sometimes rows 0 and 1 (current 15-min prices and current hour) were blank
+
+**Cause:** The "hour suppression" logic was hiding the current hour unexpectedly
+
+### Solution:
+
+  - Row 1 (current hour) now ALWAYS shows - suppression logic only applies to rows 2-3
+  - Row 0 (15-min details) also always shows for the current hour
+
+---
+
+## v6.2.1 – Current Interval Fix (2026‑03‑29)
+
+**Summary**
+
+Fixed a bug where the display was showing prices one hour ahead of the current time.
+
+### Problem: Display Showing Next Hour Instead of Current
+
+**Root Cause:**
+
+The `findCurrentPriceIndex()` function was finding the **next** 15-minute interval (first entry with timestamp >= now), but it should find the **current** interval (the one we're currently IN).
+
+For example, at 17:57:
+- The current 15-minute interval is **17:45-18:00** (price indexed at 17:45)
+- The **next** interval is 18:00-18:15 (price indexed at 18:00)
+- The buggy function returned the index for **18:00** instead of **17:45**
+- Result: Display showed hour **18** instead of hour **17**
+
+### Solution
+
+The fix calculates the **next 15-minute boundary** and finds the last entry **strictly before** that boundary:
+
+```cpp
+// Calculate the next 15-minute boundary
+const int QUARTER_SECONDS = 15 * 60; // 900 seconds
+time_t nextQuarter = ((now + QUARTER_SECONDS - 1) / QUARTER_SECONDS) * QUARTER_SECONDS;
+
+// Find the last entry strictly before nextQuarter
+for (size_t i = unixSeconds.size(); i > 0; i--) {
+    if ((time_t)unixTime < nextQuarter) {
+        return (int)(i - 1);
+    }
+}
+```
+
+**Example:**
+- At 17:57: nextQuarter = 18:00, finds last entry < 18:00 = 17:45 ✅
+- At 18:00: nextQuarter = 18:15, finds last entry < 18:15 = 18:00 ✅
+- At 18:46: nextQuarter = 19:00, finds last entry < 19:00 = 18:45 ✅
+
 ---
 
 ## v6.2.0 – DST (Daylight Saving Time) Handling Fixed (2026‑03‑29)

README.md

@@ -5,13 +5,38 @@
 This project is an Arduino‑IDE‑friendly firmware for the **Seeed XIAO ESP32‑C3** that:
 
 - Connects to Wi‑Fi.
-- Fetches **day‑ahead electricity prices** from [Energy‑Charts.info](https://energy-charts.info) (Bundesnetzagentur / SMARD.de).
+- Fetches **day‑ahead electricity prices** from [Energy‑Charts.info](https://energy-charts.info).
 - Computes final consumer prices (including configurable power‑company fee + VAT).
 - Displays current and upcoming prices on a **20x4 I²C 2004 LCD**.
 - Uses a white LED and an optional presence sensor to give quick visual feedback.
 - Stores daily price data in **NVS** to survive reboots and reduce API calls.
 
-The latest sketch implements **Version 6.2.0**, focusing on:
+The latest sketch implements **Version 6.2.4**.
+
+---
+
+## Version Highlights
+
+### v6.2.4 - Exact-boundary display refresh bug  (critical fix of v6.2.3 update)
+- Problem: At the exact top of the hour (e.g., 20:00:00), the display automatically refreshed but showed the PREVIOUS hour's data (19:00). This happened because the "next-boundary" rounding logic in findCurrentPriceIndex() incorrectly excluded the current interval if the time was exactly on the boundary.
+- Fix: Simplified findCurrentPriceIndex() to use a robust "last entry <= now" comparison. This ensures the display transitions to the new hour instantaneously at XX:00:00.
+
+### v6.2.3 - State-based display refresh logic  (critical fix of v6.2.2 update)
+- Problem: Screen would occasionally fail to update if the ESP32 was busy (fetching data or reconnecting WiFi) during the exact 00/15/30/45 minute mark.
+- Fix: Switched from "Event-Based" (refresh only AT minute X) to "State-Based" (refresh IF current time != last refresh time). This ensures the screen updates immediately even if the device was busy during the transition.
+
+### v6.2.2 - Display Blank Lines Issue Fix  (critical fix of v6.2.1 update)
+  - Problem: Sometimes rows 0 and 1 (current 15-min prices and current hour) were blank.
+  - Cause: The "hour suppression" logic was hiding the current hour unexpectedly.
+  - Fix:
+    - Row 1 (current hour) now ALWAYS shows - suppression logic only applies to rows 2-3.
+    - Row 0 (15-min details) also always shows for the current hour.
+
+### v6.2.1 – Current Interval Fix (critical fix of v6.2.0 update)
+- Fixed display showing prices one hour ahead of the current time.
+- `findCurrentPriceIndex()` now correctly returns the current 15-minute interval.
+
+Major update sketch implements **Version 6.2.0**, focusing on:
 
 - **Version 6.2.0 FIX**: **DST (Daylight Saving Time) handling fully fixed** – the ticker now works correctly on ALL days including DST switch days (spring forward and fall back). Uses timestamp-based price lookups instead of arithmetic calculations.
 - Version 6.1.2 fix: restore correct **white LED indicator** behavior (ESP32 PWM fix; no dim glow when off).

VERSION.md

@@ -2,13 +2,40 @@
 
 ## Current firmware
 
-- **Version:** 6.2.0
-- **Release date:** 2026-03-29
+- **Version:** 6.2.4
+- **Release date:** 2026-04-01
 - **Target MCU:** Seeed XIAO ESP32‑C3
 - **Display:** 20x4 I²C LCD (PCF8574, default address `0x27`)
 - **API endpoint:** `https://api.energy-charts.info/price?bzn=SI`
 - **Resolution:** 15‑minute intervals, hourly averages for overview
 
+ ## Highlights of v6.2.4
+
+ - **BUG FIX:** Exact-boundary display refresh bug
+ - Problem: At the exact top of the hour (e.g., 20:00:00), the display automatically refreshed but showed the PREVIOUS hour's data (19:00). This happened because the "next-boundary" rounding logic in findCurrentPriceIndex() incorrectly excluded the current interval if the time was exactly on the boundary.
+ - Fix: Simplified findCurrentPriceIndex() to use a robust "last entry <= now" comparison. This ensures the display transitions to the new hour instantaneously at XX:00:00.
+
+ ## Highlights of v6.2.3
+
+- **BUG FIX**: State-based display refresh logic
+- Problem: Screen would occasionally fail to update if the ESP32 was busy (fetching data or reconnecting WiFi) during the exact 00/15/30/45 minute mark.
+- Fix: Switched from "Event-Based" (refresh only AT minute X) to "State-Based" (refresh IF current time != last refresh time). This ensures the screen updates immediately even if the device was busy during the transition.
+ 
+ ## Highlights of v6.2.2
+
+- **BUG FIX**: Display blank lines issue
+- Problem: Sometimes rows 0 and 1 (current 15-min prices and current hour) were blank
+- Cause: The "hour suppression" logic was hiding the current hour unexpectedly
+- Fix:
+  - Row 1 (current hour) now ALWAYS shows - suppression logic only applies to rows 2-3
+  - Row 0 (15-min details) also always shows for the current hour
+
+## Highlights of v6.2.1
+
+- **BUG FIX**: Fixed `findCurrentPriceIndex()` to return the correct current interval.
+- Problem: At 17:57, it returned index for 18:00 instead of 17:45, causing display to show hour 18 instead of hour 17.
+- Fix: Now calculates next 15-minute boundary and finds the last entry before that boundary.
+
 ## Highlights of v6.2.0
 
 - **CRITICAL FIX**: DST (Daylight Saving Time) handling is now fully fixed for all days.
@@ -21,11 +48,6 @@
 - The ticker now works correctly on all days, including DST switch days, with no manual intervention.
 - **Future-proof**: If EU cancels DST, only the `TZ_CET_CEST` string needs updating (one line of code).
 
-For full details, see:
-
-- [CHANGELOG.md](./CHANGELOG.md)
-- [README.md](./README.md)
-
 ## Previous firmware
 
 - **Version:** 6.1.2
@@ -43,4 +65,7 @@ For full details, see:
 - **Version:** 6.1.0 (2026-01-30) – Midnight fetch and market day detection fixes
 - **Version:** 6.0.0 (2026-01-27) – NVS storage and daily fetch
 
-For detailed history, see [CHANGELOG.md](./CHANGELOG.md).
+For full details, see:
+
+- [CHANGELOG.md](./CHANGELOG.md)
+- [README.md](./README.md)