diff --git a/src/ds323x/datetime.rs b/src/ds323x/datetime.rs
index 17e250d..e638f5b 100644
--- a/src/ds323x/datetime.rs
+++ b/src/ds323x/datetime.rs
@@ -195,6 +195,29 @@ where
         }
     }
 
+    /// Set the date and time.
+    ///
+    /// Will return an `Error::InvalidInputData` if any of the parameters is out of range.
+    pub fn set_datetime(&mut self, datetime: &DateTime) -> Result<(), Error<E>> {
+        if datetime.year < 2000 || datetime.year > 2100 ||
+           datetime.month < 1   || datetime.month > 12  ||
+           datetime.day < 1     || datetime.day > 31    ||
+           datetime.weekday < 1 || datetime.weekday > 7 ||
+           datetime.minute > 59 ||
+           datetime.second > 59 {
+            return Err(Error::InvalidInputData);
+        }
+        let (month, year) = month_year_to_registers(datetime.month, datetime.year);
+        let mut payload = [Register::SECONDS,
+                           decimal_to_packed_bcd(datetime.second),
+                           decimal_to_packed_bcd(datetime.minute),
+                           self.get_hours_register_value(&datetime.hour)?,
+                           decimal_to_packed_bcd(datetime.weekday),
+                           decimal_to_packed_bcd(datetime.day),
+                           month, year];
+        self.iface.write_data(&mut payload)
+}
+
     fn write_register_decimal(&mut self, register: u8, decimal_number: u8) -> Result<(), Error<E>> {
         self.iface.write_register(register, decimal_to_packed_bcd(decimal_number))
     }
@@ -223,6 +246,16 @@ fn year_from_registers(month: u8, year: u8) -> u16 {
     }
 }
 
+fn month_year_to_registers(month: u8, year: u16) -> (u8, u8) {
+    if year > 2099 {
+        let month = BitFlags::CENTURY | decimal_to_packed_bcd(month);
+        (month, decimal_to_packed_bcd((year - 2100) as u8))
+    }
+    else {
+        (decimal_to_packed_bcd(month), decimal_to_packed_bcd((year - 2000) as u8))
+    }
+}
+
 fn is_24h_format(hours_data: u8) -> bool {
     hours_data & BitFlags::H24_H12 == 0
 }
diff --git a/tests/ds323x.rs b/tests/ds323x.rs
index d9c6f5a..4357d3f 100644
--- a/tests/ds323x.rs
+++ b/tests/ds323x.rs
@@ -26,10 +26,10 @@ macro_rules! get_param_test {
 }
 
 macro_rules! get_param_read_array_test {
-    ($method:ident, $value:expr, $register1:ident, [ $( $bin:expr ),+ ], [ $( $bin2:expr ),+ ]) => {
+    ($method:ident, $value:expr, $register1:ident, [ $( $read_bin:expr ),+ ], [ $( $read_bin2:expr ),+ ]) => {
         _get_param_test!($method, $value,
-            [ I2cTrans::write_read(DEV_ADDR, vec![Register::$register1], vec![$( $bin ),*]) ],
-            [ SpiTrans::transfer(vec![Register::$register1, $( $bin2 ),*], vec![Register::$register1, $( $bin ),*]) ]);
+            [ I2cTrans::write_read(DEV_ADDR, vec![Register::$register1], vec![$( $read_bin ),*]) ],
+            [ SpiTrans::transfer(vec![Register::$register1, $( $read_bin2 ),*], vec![Register::$register1, $( $read_bin ),*]) ]);
     };
 }
 
@@ -49,6 +49,14 @@ macro_rules! set_param_test {
     };
 }
 
+macro_rules! set_param_write_array_test {
+    ($method:ident, $value:expr, $register:ident, [ $( $exp_bin:expr ),+ ] ) => {
+        _set_param_test!($method, $value,
+            [ I2cTrans::write(DEV_ADDR, vec![Register::$register, $( $exp_bin ),*]) ],
+            [ SpiTrans::write(vec![Register::$register + 0x80, $( $exp_bin ),*]) ]);
+    };
+}
+
 macro_rules! read_set_param_write_two_test {
     ($method:ident, $value:expr, $register:ident, $binary_value1_read:expr, $bin1:expr, $bin2:expr) => {
         _set_param_test!($method, $value,
@@ -173,9 +181,13 @@ mod year {
 mod datetime {
     use super::*;
     const DT : DateTime = DateTime { year: 2018, month: 8, day: 13, weekday: 2,
-                              hour: Hours::H24(23), minute: 59, second: 58 };
+                                     hour: Hours::H24(23), minute: 59, second: 58 };
     get_param_read_array_test!(get_datetime, DT, SECONDS,
         [0b0101_1000, 0b0101_1001, 0b0010_0011, 0b0000_0010,
          0b0001_0011, 0b0000_1000, 0b0001_1000],
         [0, 0, 0, 0, 0, 0, 0]);
+
+    set_param_write_array_test!(set_datetime, &DT, SECONDS,
+        [0b0101_1000, 0b0101_1001, 0b0010_0011, 0b0000_0010,
+         0b0001_0011, 0b0000_1000, 0b0001_1000]);
 }