Using the BM8563 RTC with MaixPy

Introduction to BM8563

BM8563 is a real-time clock (RTC) chip that stores the time and date. With a backup battery, it continues keeping time while the device is powered off.

Using BM8563 in MaixPy

When creating a BM8563 object, specify the I2C bus connected to the chip. The onboard BM8563 on MaixCAM Pro uses I2C-4.

Example:

from maix import ext_dev, pinmap, err, time

### Enable I2C
# ret = pinmap.set_pin_function("PIN_NAME", "I2Cx_SCL")
# if ret != err.Err.ERR_NONE:
#     print("Failed in function pinmap...")
#     exit(-1)
# ret = pinmap.set_pin_function("PIN_NAME", "I2Cx_SDA")
# if ret != err.Err.ERR_NONE:
#     print("Failed in function pinmap...")
#     exit(-1)

BM8563_I2CBUS_NUM = 4

rtc = ext_dev.bm8563.BM8563(BM8563_I2CBUS_NUM)

### 2020-12-31 23:59:45
t = [2020, 12, 31, 23, 59, 45]

# Set time
rtc.datetime(t)

while True:
    rtc_now = rtc.datetime()
    print(f"{rtc_now[0]}-{rtc_now[1]}-{rtc_now[2]} {rtc_now[3]}:{rtc_now[4]}:{rtc_now[5]}")
    time.sleep(1)

When using the onboard BM8563 on MaixCAM Pro, you do not need to configure the I2C-4 pins separately.

The example sets the BM8563 time and then reads it once per second.

The next example synchronizes the BM8563 time and the system time.

from maix import ext_dev, pinmap, err, time

### Enable I2C
# ret = pinmap.set_pin_function("PIN_NAME", "I2Cx_SCL")
# if ret != err.Err.ERR_NONE:
#     print("Failed in function pinmap...")
#     exit(-1)
# ret = pinmap.set_pin_function("PIN_NAME", "I2Cx_SDA")
# if ret != err.Err.ERR_NONE:
#     print("Failed in function pinmap...")
#     exit(-1)


BM8563_I2CBUS_NUM = 4

rtc = ext_dev.bm8563.BM8563(BM8563_I2CBUS_NUM)

### Update RTC time from system
rtc.systohc()

### Update system time from RTC
# rtc.hctosys()

while True:
    rtc_now = rtc.datetime()
    print(f"{rtc_now[0]}-{rtc_now[1]}-{rtc_now[2]} {rtc_now[3]}:{rtc_now[4]}:{rtc_now[5]}")
    time.sleep(1)

The BM8563 API protects concurrent access to the same chip. You can create objects in different parts of a program without causing a data race during simultaneous reads or writes.

The timetuple passed to a BM8563 object uses (year, month, day[, hour[, minute[, second]]]). Year, month, and day are required; omitted time fields are left unchanged. A successful read returns a six-item list, (year, month, day, hour, minute, second). An empty result indicates an error.

See the BM8563 API documentation for all parameters.