Add support for setting the comparator latching

4 files changed, 41 insertions, 2 deletions

diff --git a/src/devices/ads1x1x/features/tier2.rs b/src/devices/ads1x1x/features/tier2.rs
index 7d22796..43dce5c 100644
--- a/src/devices/ads1x1x/features/tier2.rs
+++ b/src/devices/ads1x1x/features/tier2.rs
@@ -3,7 +3,7 @@
 //! These are the features included only in ADS1x14, ADS1x15
 
 use { Ads1x1x, Error, interface, ic, ComparatorMode, ComparatorPolarity,
-      Register, BitFlags };
+      ComparatorLatching, Register, BitFlags };
 
 impl<DI, IC, MODE, E> Ads1x1x<DI, IC, MODE>
 where
@@ -33,4 +33,16 @@ where
         self.config = config;
         Ok(())
     }
+
+    /// Set comparator latching
+    pub fn set_comparator_latching(&mut self, latching: ComparatorLatching) -> Result<(), Error<E>> {
+        let config;
+        match latching {
+            ComparatorLatching::Nonlatching => config = self.config.with_low( BitFlags::COMP_LAT),
+            ComparatorLatching::Latching    => config = self.config.with_high(BitFlags::COMP_LAT)
+        }
+        self.iface.write_register(Register::CONFIG, config.bits)?;
+        self.config = config;
+        Ok(())
+    }
 }
diff --git a/src/lib.rs b/src/lib.rs
index ee37a1d..f144b01 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -175,6 +175,26 @@ pub enum ComparatorPolarity {
     ActiveHigh
 }
 
+/// Comparator polarity (only for ADS1x14, ADS1x15)
+///
+/// Select whether the ALERT/RDY pin latches after being asserted or clears
+/// after conversions are within the margin of the upper and lower
+/// threshold values.
+#[derive(Debug, Clone, PartialEq)]
+pub enum ComparatorLatching {
+    /// Nonlatching (default)
+    ///
+    /// The ALERT/RDY pin does not latch when asserted.
+    Nonlatching,
+    /// Latching
+    ///
+    /// The asserted ALERT/RDY pin remains latched until conversion data are
+    /// read by the master or an appropriate SMBus alert response is sent by
+    /// the master. The device responds with its address, and it is the lowest
+    /// address currently asserting the ALERT/RDY bus line.
+    Latching
+}
+
 /// Possible slave addresses
 #[derive(Debug, Clone)]
 pub enum SlaveAddr {
@@ -220,6 +240,7 @@ impl BitFlags {
     const DR0          : u16 = 0b0000_0000_0010_0000;
     const COMP_MODE    : u16 = 0b0000_0000_0001_0000;
     const COMP_POL     : u16 = 0b0000_0000_0000_1000;
+    const COMP_LAT     : u16 = 0b0000_0000_0000_0100;
 }
 
 
diff --git a/tests/common/mod.rs b/tests/common/mod.rs
index 8ffd50e..695280e 100644
--- a/tests/common/mod.rs
+++ b/tests/common/mod.rs
@@ -23,6 +23,7 @@ impl BitFlags {
     pub const DR0          : u16 = 0b0000_0000_0010_0000;
     pub const COMP_MODE    : u16 = 0b0000_0000_0001_0000;
     pub const COMP_POL     : u16 = 0b0000_0000_0000_1000;
+    pub const COMP_LAT     : u16 = 0b0000_0000_0000_0100;
 }
 
 pub struct Config {
diff --git a/tests/tier2_i2c.rs b/tests/tier2_i2c.rs
index e8162c4..e032a6c 100644
--- a/tests/tier2_i2c.rs
+++ b/tests/tier2_i2c.rs
@@ -2,7 +2,7 @@ extern crate embedded_hal;
 extern crate embedded_hal_mock as hal;
 use hal::i2c::Transaction as I2cTrans;
 extern crate ads1x1x;
-use ads1x1x::{ ComparatorMode, ComparatorPolarity };
+use ads1x1x::{ ComparatorMode, ComparatorPolarity, ComparatorLatching};
 
 #[macro_use]
 mod common;
@@ -33,4 +33,9 @@ mod can_set_comparator_polarity {
     set_value_test!(high, set_comparator_polarity, ComparatorPolarity::ActiveHigh, Config::default().with_high(BitFlags::COMP_POL));
 }
 
+mod can_set_comparator_latching {
+    use super::*;
+    set_value_test!(non, set_comparator_latching, ComparatorLatching::Nonlatching, Config::default().with_low( BitFlags::COMP_LAT));
+    set_value_test!(lat, set_comparator_latching, ComparatorLatching::Latching,    Config::default().with_high(BitFlags::COMP_LAT));
+}