Details

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BUY DS1218S+ https://www.utsource.net/itm/p/12408884.html

Parameter	Description
Device Type	Real-Time Clock (RTC) with SRAM and Battery Backup
Package	16-SOIC (Small Outline Integrated Circuit)
Operating Voltage	VCC: 2.2V to 5.5V; VBAT: 1.8V to 3.6V
Operating Temperature	-40°C to +85°C
Clock Accuracy	±2 minutes per year at 25°C
SRAM Size	1024 bytes (1K x 8)
Battery Backup	Lithium coin cell battery (CR1220 or similar)
Communication Interface	I2C (Two-wire Serial Interface)
I2C Address	0x68 (Fixed)
Oscillator Frequency	32.768 kHz
Power Consumption	< 1 μA in battery backup mode
Write Protection	Hardware write protect pin (WP)
Supply Current	100 μA typical (active mode)
Quartz Crystal	External 32.768 kHz crystal required

Instructions for Use

1. Power Supply Connection

   • Connect VCC to the main power supply (2.2V to 5.5V).
   • Connect VBAT to a backup battery (1.8V to 3.6V).

2. Ground Connection

   • Ensure a common ground (GND) is connected to both VCC and VBAT.

3. I2C Interface

   • Connect SDA (Data) and SCL (Clock) lines to the I2C bus.
   • Use pull-up resistors on SDA and SCL lines (typically 4.7kΩ to VCC).

4. Write Protection

   • Set the WP (Write Protect) pin to GND to enable writing to the SRAM.
   • Set the WP pin to VCC to disable writing to the SRAM.

5. External Crystal

   • Connect a 32.768 kHz quartz crystal between X1 and X2 pins for accurate timekeeping.

6. Initialization

   • Initialize the RTC using the I2C interface to set the current date and time.
   • Use the appropriate I2C commands to read and write data from/to the SRAM.

7. Reading Time and Date

   • Use the I2C interface to read the time and date registers.
   • The time and date are stored in BCD (Binary-Coded Decimal) format.

8. Writing Time and Date

   • Convert the desired time and date to BCD format.
   • Write the values to the appropriate registers using the I2C interface.

9. Battery Backup

   • Ensure the backup battery is installed correctly to maintain the clock and SRAM data during power loss.

10. Testing

    • After setup, verify the operation by reading the time and date to ensure they are updating correctly.

For detailed register maps and specific I2C commands, refer to the DS1218S+ datasheet provided by the manufacturer.

(For reference only)