# Electricity Price Ticker – Version Information ## Current firmware - **Version:** 7.0 - **Release date:** 2026-04-03 - **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 v7.0 ### MAJOR UPGRADE: Rolling 48-Hour Logic & Midnight Bridge This version is the **"Golden Build"** for this hardware. It represents the culmination of hardware stability fixes from v6.2.4 combined with revolutionary new 48-hour price prediction capabilities. #### 1. The Midnight Bridge (Rollover Logic) The most complex part of electricity tickers is handling the midnight transition. This code now correctly detects the moment the local clock moves from 23:59:59 to 00:00:00. **The Swap:** Instead of waiting for a slow API call at midnight (which usually fails because the server hasn't updated yet), the code instantly promotes the "Tomorrow" buffer to become "Today" data. **The NVS Update:** The code correctly serializes the new "Today" data and saves it to NVS immediately after the swap. This ensures that if power cuts at 00:05 AM, the device reboots with the correct data already loaded. #### 2. Dual-Buffer NVS System The ticker now stores "Today" and "Tomorrow" data independently in NVS: - **Today buffer (`doc`)**: Contains the current day's price data - **Tomorrow buffer (`docTomorrow`)**: Contains the next day's price data - **NVS keys**: `data_prc`/`data_day`/`data_mon`/`data_year` for today, `data_prc_t`/`data_store_t` for tomorrow #### 3. Smart Fetching & API URL The logic for fetching tomorrow's data is implemented correctly: - **URL Construction**: Adding `&start=YYYY-MM-DD` dynamically after 14:00 (2 PM) queries the Energy-Charts API for the next day - **Validation**: In `processJsonData()`, the code compares the timestamp in the JSON against the target date, preventing the "Tomorrow" buffer from being filled with "Today's" data if the API is lagging #### 4. Seamless 48H Scrolling If next-day data is available, the button allows scrolling up to **47 hours ahead**: - **Visual Distinction**: Using `HH:>>` for tomorrow's hours prevents the user from confusing a cheap price "tomorrow" with a cheap price "today" - **Index Safety**: The code correctly uses `lowestPriceIndexTomorrow` and `highestPriceIndexTomorrow` when the display is in the "tomorrow" range, ensuring the Min/Max icons appear on the correct 15-minute segments #### 5. Hardware Stability (Inherited from v6.2.4) All v6.2.4 hardware stability fixes are preserved: - **Refresh Logic**: "State-Based" refresh ensures the display updates exactly at 00, 15, 30, and 45 minutes past the hour, even if the CPU is busy with a background fetch - **LED Indicators**: White LED for low price and Built-in LED for connectivity remain pinned to the actual current price, even when the user is scrolling through future data on the screen #### Final "Sanity Check" Verdict **Status:** Verified. The code is safe to deploy. The transition from 15-minute intervals to the midnight rollover is now seamless. The "1 AM fetch gap" that plagues most electricity tickers has been successfully bypassed. --- ## 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. - Previously, the code assumed every day has exactly 96 price entries (24h × 4). This caused incorrect price display on DST switch days: - Spring forward (March): Only 92 entries → wrong prices displayed - Fall back (October): 100 entries → wrong prices displayed - **Solution**: All price lookups now use timestamp-based searching through the `unix_seconds` array instead of arithmetic calculation (`hourIndex * 4`). - New functions: `findPriceIndexForHour()`, `findCurrentPriceIndex()`, `getHourFromPriceIndex()` - Updated functions: `getHourlyAverage()`, `display15MinuteDetails()`, `displayPriceRow()`, `displayPrimaryList()`, `updateLeds()` - 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). ## Previous firmware - **Version:** 6.1.2 - **Release date:** 2026-03-11 - **Target MCU:** Seeed XIAO ESP32‑C3 ## Highlights of v6.1.2 - Fix: restore proper white LED price indicator behavior on ESP32 by avoiding mixing PWM (`analogWrite`) and `digitalWrite` on the same pin. - Fix: LED is now truly off when backlight/LED gating turns it off (no more "dim glow"). ## Earlier firmware - **Version:** 6.1.1 (2026-03-07) – Daily low/high marker includes negative and zero prices - **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 full details, see: - [CHANGELOG.md](./CHANGELOG.md) - [README.md](./README.md)