Example 16: RTC Clock (System NTP)

Experiment Overview

ESP32 does not have an independent RTC clock chip (time is lost on power-off), but after WiFi connection, NTP (Network Time Protocol) can be used to automatically sync network time. FastBee automatically performs NTP time sync after connecting to the network, which can be used for scheduled tasks and time display.

Hardware Wiring

No additional hardware needed for this experiment, utilizing ESP32's WiFi capability to obtain NTP time.

For time retention on power-off, refer to Example 17 (DS1302 External RTC).

JSON Configuration Example

Time-related functions are used through peripheral execution timer triggers:

{
  "peripherals": [
    {
      "id": "tm1637_clock",
      "name": "Clock Display",
      "type": 47,
      "enabled": false,
      "pins": [18, 19],
      "params": { "brightness": 4 }
    }
  ]
}

Peripheral Execution Linkage

Scenario 1: Update Time Display Every Second (Timer Trigger)

Function: Update seven-segment display with current system time every second (with colon blinking)

Web Interface Configuration Steps

Step 1: Ensure TM1637 seven-segment display is configured

• Peripheral ID: tm1637_clock
• Type: Seven-segment display

Step 2: Create Rule

1. Click Peripheral Execution in the left menu
2. Click New Rule button
3. Fill in basic configuration:
   • Rule Name: Clock Display
   • Report Data: ✅ Enable
   • Enabled: ✅ Enable

Step 3: Configure Trigger

1. Click Add Trigger button

2. Fill in trigger configuration:

   Field	Value	Description
   Trigger Type	Select Timer Trigger	Periodic update
   Timer Mode	Select Fixed Interval	By millisecond interval
   Interval Time	1000	Update every 1 second

Step 4: Configure Action

1. Click Add Action button

2. Fill in:

   • Action Type: Select Display Time
   • Target Peripheral: Select tm1637_clock
   • Show Colon: ✅ Enable

3. Click Save button

---

Scenario 2: Auto Light On at 6 AM Daily (Cron Timer)

Function: Automatically turn on LED at 6 AM every day

Web Interface Configuration Steps

1. Create rule, name: Daily 6AM Light On
2. Trigger configuration:
   • Trigger Type: Select Timer Trigger
   • Timer Mode: Select Cron Expression
   • Cron Expression: 0 6 * * * (every day at 6:00)
3. Action configuration:
   • Action Type: Select LOW Level (common-anode LED)
   • Target Peripheral: Select led_d1
4. Click Save

Cron Expression Examples

Cron Expression	Description	Execution Time
0 6 * * *	Every day 6:00	Every morning at 6 AM
0 18 * * *	Every day 18:00	Every evening at 6 PM
*/5 * * * *	Every 5 minutes	Every 5 minutes
0 */2 * * *	Every 2 hours	Every 2 hours on the hour

Notes

1. NTP Requires Network: First boot needs network connection to get time, offline mode continues from last sync
2. Precision: NTP sync precision is ~±50ms, local crystal drift is ~±2ppm
3. Power Loss: ESP32 RTC time is cleared on power-off, needs NTP re-sync on power-up
4. Cron Expression: Supports standard 5-field format: minute hour day month weekday
5. Timezone: System defaults to UTC+8, can be modified in device configuration