hello_rtc_ntp

# Hello RTC NTP Example

Demonstrates BM8563 RTC initialization, NTP time synchronization, and LVGL display. Supports both WiFi and LTE Modem (A7670) for network connectivity.

## Features

- **BM8563 RTC** - Initialize and read/write real-time clock
- **Automatic Network Selection** - Runtime detection selects the best available connection:
  - **LTE Modem (A7670)** - Used when `CONFIG_CUBE32_MODEM_ENABLED` is set, the modem module is physically detected at boot, **and** the modem Active flag (NVS `act_modem`) is enabled
  - **WiFi** - Used as fallback when modem is not enabled, not detected, or the Active flag is set to off
- **Connection Mode Badge** - Top-right corner of the display shows `📞 4G/LTE` or `📶 WiFi` from boot
- **NTP Synchronization** - Sync time with `time.cloudflare.com` over the active connection
- **Automatic RTC Update** - Update RTC with NTP time after synchronization
- **LVGL Display** - Dark theme UI showing:
  - Current date and time (large format with short month names)
  - Network connection status and IP address (WiFi or LTE)
  - NTP synchronization status
  - Last sync timestamp
- **Timezone Support** - Display time in configured local timezone

## Hardware Requirements

- CUBE32 board with:
  - ST7789 display
  - BM8563 RTC chip
  - WiFi connectivity (always required as fallback)
  - Optional: A7670 LTE modem module (auto-detected at boot)

## Configuration

### 1. Enable Required Components

In `idf.py menuconfig`:

**CUBE32 Board Configuration → RTC Configuration:**
- ✅ Enable RTC (BM8563)
- Set Local Time Zone (default: Asia/Singapore)

**CUBE32 Board Configuration → Display Configuration:**
- ✅ Enable Display
- ✅ Enable LVGL

**Component config → LVGL → Font usage:**
- ✅ Enable Montserrat 14
- ✅ Enable Montserrat 24 (for date display)
- ☑️ Enable Montserrat 32 or 48 (optional, for larger time display)
- ☑️ Enable Montserrat 64 (optional, for very large time display)

**CUBE32 WiFi Configuration:**
- Set WiFi SSID (your network name)
- Set WiFi Password

> **Note:** WiFi credentials are always required even when using the modem — they are used as the fallback connection if the modem module is not present at boot.

**Optional — LTE Modem:**

**CUBE32 Board Configuration → Modem Configuration:**
- ✅ Enable Modem (A7670)

When modem support is enabled, the A7670 module is physically detected at boot (TCA9554 GPIO expander at I2C address 0x22), **and** the modem Active flag in NVS is `true`, the demo automatically uses LTE for NTP synchronization.

Fallback to WiFi occurs in any of these cases:
- Modem module not physically present
- Modem Active flag (`act_modem`) is set to `false` via the BLE OTA configuration tool

The Active flag is configured via the **CUBE32 Mobile App** using the BLE OTA subsystem and stored in NVS — it survives reboots.

### 2. Select Application

**CUBE32 Application Selection:**
- Select "Hello RTC NTP Example"

### 3. Timezone Configuration

The timezone is configured in menuconfig:

**CUBE32 Board Configuration → RTC Configuration → Local Time Zone**

Common timezone values:
- `Asia/Singapore` - Singapore/Malaysia Time (GMT+8, default)
- `Asia/Hong_Kong` - Hong Kong Time (GMT+8)
- `Asia/Shanghai` - China Standard Time (GMT+8)
- `Asia/Tokyo` - Japan Standard Time (GMT+9)
- `UTC` - UTC
- `America/Los_Angeles` - US Pacific Time (with DST)
- `America/New_York` - US Eastern Time (with DST)
- `Europe/London` - UK Time (with DST)

Or use POSIX timezone format:
- `CST-8` - China/Hong Kong/Singapore (no DST)
- `PST8PDT,M3.2.0,M11.1.0` - US Pacific (with DST)
- `EST5EDT,M3.2.0,M11.1.0` - US Eastern (with DST)

## Build and Flash

```bash
idf.py build
idf.py -p PORT flash monitor
```

## Expected Behavior

1. Display shows "CUBE32 RTC + NTP" title
2. Network connects (LTE modem if detected, otherwise WiFi — shows IP address)
3. NTP syncs with time server (may take a few seconds)
4. Time display updates every 500ms
5. RTC is automatically updated with NTP time
6. Time persists after power cycle (battery-backed RTC)

## Display Layout

```
┌─────────────────────────┐
│ CUBE32 RTC + NTP 📶WiFi │  ← Connection mode badge (top-right)
│                         │
│       14:30:25          │  ← Large time
│                         │
│     Jan 9, 2024         │  ← Date
│                         │
│       Thursday          │  ← Weekday
│                         │
├─────────────────────────┤
│ 📶 Connected: 192.168.x │  ← WiFi or 📞 LTE: x.x.x.x
│ ✓ NTP Synced            │
│ Last sync: 14:30:00     │
└─────────────────────────┘
```

The connection mode badge in the top-right corner (`📞 4G/LTE` or `📶 WiFi`) is determined at boot and does not change at runtime.

## Troubleshooting

**WiFi won't connect:**
- Check SSID and password in menuconfig
- Verify WiFi network is 2.4GHz (ESP32 doesn't support 5GHz)

**LTE modem not used despite being enabled:**
- Confirm the A7670 module is physically installed (modem detection is runtime, not just Kconfig)
- Check that the modem Active flag is enabled — set it via the **CUBE32 Mobile App** (BLE OTA subsystem) and verify `act_modem = true` in NVS
- Check serial log for one of:
  - `"Modem module detected and active — using LTE"` → modem path taken
  - `"Modem detected but Active flag is off — falling back to WiFi"` → module present but flag is off
  - `"Modem enabled in Kconfig but module not detected"` → module not physically installed

**NTP won't sync:**
- Ensure network is connected (check IP address shown on display)
- Check firewall allows NTP (UDP port 123)
- Try different NTP server in `main.cpp` (e.g., `"pool.ntp.org"`)

**Time is wrong:**
- Verify timezone setting matches your location
- NTP always returns UTC time - timezone conversion happens locally

**Display not working:**
- Verify LVGL fonts are enabled in menuconfig
- Check display is properly connected