diff --git a/adafruit_pcf8523.py b/adafruit_pcf8523.py
index a885862..0329b49 100644
--- a/adafruit_pcf8523.py
+++ b/adafruit_pcf8523.py
@@ -101,6 +101,18 @@ class PCF8523:
     battery_low = i2c_bit.ROBit(0x02, 2)
     """True if the battery is low and should be replaced."""
 
+    high_capacitance = i2c_bit.RWBit(0x00, 7)
+    """True for high oscillator capacitance (12.5pF), otherwise lower (7pF)"""
+
+    calibration_schedule_per_minute = i2c_bit.RWBit(0x0E, 7)
+    """False to apply the calibration offset every 2 hours (1 LSB = 4.340ppm);
+    True to offset every minute (1 LSB = 4.069ppm).  The default, False,
+    consumes less power.  See datasheet figures 28-31 for details."""
+
+    calibration = i2c_bits.RWBits(7, 0xE, 0, signed=True)
+    """Calibration offset to apply, from -64 to +63.  See the PCF8523 datasheet
+    figure 18 for the offset calibration calculation workflow."""
+
     def __init__(self, i2c_bus):
         self.i2c_device = I2CDevice(i2c_bus, 0x68)