AM1805 RTC Driver for Zephyr OS (Nordic)

This repository provides a C driver implementation for the Ambiq AM1805 Real-Time Clock (RTC), specifically designed to run on Zephyr OS using Nordic Semiconductor hardware. The driver enables basic RTC functionalities, including reading time, setting alarms, and configuring timers.

Features

• Read the current RTC time.
• Set an alarm.
• Configure a countdown timer.
• Uses Zephyr's device driver model.
• Compatible with Nordic Semiconductor development kits.

Hardware Requirements

• Nordic Development Kit (e.g., nRF52840-DK, nRF5340-DK, etc.)
• AM1805 RTC Module
• I2C Connection between the Nordic DK and AM1805

Zephyr Configuration

Ensure that the prj.conf file includes the required configurations for I2C and the RTC:

CONFIG_I2C=y
CONFIG_LOG=y

The AM1805 driver should be enabled in the device tree (.dts):

&i2c1 {
    status = "okay";
    clock-frequency = <I2C_BITRATE_STANDARD>;
    am1805: am1805@68 {
        compatible = "ambiq,am1805";
        reg = <0x68>;
        label = "AM1805";
    };
};

Building and Flashing

To build the application for Nordic hardware:

west build -b nrf52840dk_nrf52840 .
west flash

Example Applications

1. Read RTC Time

#include <zephyr/kernel.h>
#include <zephyr/device.h>
#include <zephyr/drivers/i2c.h>
#include "am1805.h"

void main(void) {
    struct am1805_time time;
    if (am1805_get_time(&time) == 0) {
        printk("Time: %02d:%02d:%02d\n", time.hours, time.minutes, time.seconds);
    } else {
        printk("Failed to read RTC time\n");
    }
}

2. Set an Alarm

#include "am1805.h"

void main(void) {
    struct am1805_time alarm_time = { .hours = 8, .minutes = 30, .seconds = 0 };
    am1805_set_alarm(&alarm_time);
}

3. Set a Countdown Timer

#include "am1805.h"

void main(void) {
    am1805_set_timer(10); // Set a timer for 10 seconds
}

Power Consumption experiment

• Measurement device: Nordic PPK2
• Condition: Input supply to VCC2 (main power souce)
• Result: 1.07uA @ 1.8V (datasheet: 50nA chip only)

License

This project is licensed under the MIT License. See the LICENSE file for details.

Author

Developed and maintained by @ch-binh. For any queries or contributions, please contact pcbinh.3005@gmail.com.

Contributing

Contributions are welcome! Please fork this repository and submit pull requests. For major changes, please open an issue first to discuss what you would like to change.

Acknowledgments

• Thanks to the Zephyr Project for providing an excellent RTOS.
• Special thanks to Nordic Semiconductor for their development kits and support.
• Inspired by the work of the open-source community.

References

• Zephyr Project Documentation
• Nordic Semiconductor Documentation
• AM1805 RTC Datasheet