Example 17: DS1302 RTC Clock

Experiment Overview

DS1302 is a low-power real-time clock chip that can maintain timekeeping after power-off via a coin cell battery. FastBee has a built-in DS1302 dedicated peripheral type (type: 50), supporting time read/set, trickle charging and 31 bytes of user RAM.

Hardware Wiring

Board Label	GPIO Pin	Connected Device
CLK	GPIO14	DS1302 clock line
DAT	GPIO27	DS1302 data line
RST	GPIO26	DS1302 reset/enable

DS1302 uses a three-wire interface (CE/IO/SCLK), requiring 3 GPIO pins.

JSON Configuration Example

{
  "peripherals": [
    {
      "id": "rtc_clk",
      "name": "DS1302-CLK",
      "type": 12,
      "enabled": false,
      "pins": [14],
      "params": { "initialState": 0 }
    },
    {
      "id": "rtc_dat",
      "name": "DS1302-DAT",
      "type": 12,
      "enabled": false,
      "pins": [27],
      "params": { "initialState": 0 }
    },
    {
      "id": "rtc_rst",
      "name": "DS1302-RST",
      "type": 12,
      "enabled": false,
      "pins": [26],
      "params": { "initialState": 0 }
    }
  ]
}

Peripheral Execution Linkage (Plan A: NTP Approach)

Scenario: Periodic Time Display (Timer Trigger)

Function: Update seven-segment display with NTP-synced system time every second

Web Interface Configuration Steps

Step 1: Ensure TM1637 seven-segment display is configured

• Peripheral ID: tm1637_01
• 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: Periodic Time 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	1 second

Step 4: Configure Action

1. Click Add Action button

2. Fill in:

   • Action Type: Select Display Time
   • Target Peripheral: Select tm1637_01

3. Click Save button

Approach Comparison

Approach	Pros	Cons	Use Case
NTP	High precision, no hardware needed	Requires network	Networked devices
DS1302	Retains on power-off, works offline	Extra hardware needed, lower precision	Offline devices

Notes

1. Battery: DS1302 needs a CR2032 coin cell to maintain time during power-off
2. NTP Priority: In networked environments, recommend NTP; DS1302 is suited for offline scenarios
3. Driver Support: FastBee has built-in DS1302 driver (FASTBEE_ENABLE_DS1302=1)
4. Precision: DS1302 precision is ~±2ppm (~5 seconds per month)
5. Communication Protocol: DS1302 uses 3-wire SPI (non-standard SPI), timing requires software emulation