Add support for setting the comparator polarity

4 files changed, 43 insertions, 3 deletions

diff --git a/src/devices/ads1x1x/features/tier2.rs b/src/devices/ads1x1x/features/tier2.rs
index d238691..7d22796 100644
--- a/src/devices/ads1x1x/features/tier2.rs
+++ b/src/devices/ads1x1x/features/tier2.rs
@@ -2,7 +2,8 @@
 //!
 //! These are the features included only in ADS1x14, ADS1x15
 
-use { Ads1x1x, Error, interface, ic, ComparatorMode, Register, BitFlags };
+use { Ads1x1x, Error, interface, ic, ComparatorMode, ComparatorPolarity,
+      Register, BitFlags };
 
 impl<DI, IC, MODE, E> Ads1x1x<DI, IC, MODE>
 where
@@ -20,4 +21,16 @@ where
         self.config = config;
         Ok(())
     }
+
+    /// Set comparator polarity
+    pub fn set_comparator_polarity(&mut self, polarity: ComparatorPolarity) -> Result<(), Error<E>> {
+        let config;
+        match polarity {
+            ComparatorPolarity::ActiveLow  => config = self.config.with_low( BitFlags::COMP_POL),
+            ComparatorPolarity::ActiveHigh => config = self.config.with_high(BitFlags::COMP_POL)
+        }
+        self.iface.write_register(Register::CONFIG, config.bits)?;
+        self.config = config;
+        Ok(())
+    }
 }
diff --git a/src/lib.rs b/src/lib.rs
index 21b63c5..7dc1388 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -124,6 +124,15 @@ pub enum ComparatorMode {
     Window
 }
 
+/// Comparator polarity (only for ADS1x14, ADS1x15)
+#[derive(Debug, Clone)]
+pub enum ComparatorPolarity {
+    /// Active low (default)
+    ActiveLow,
+    /// Active high
+    ActiveHigh
+}
+
 /// Possible slave addresses
 #[derive(Debug, Clone)]
 pub enum SlaveAddr {
@@ -168,6 +177,7 @@ impl BitFlags {
     const DR1          : u16 = 0b0000_0000_0100_0000;
     const DR0          : u16 = 0b0000_0000_0010_0000;
     const COMP_MODE    : u16 = 0b0000_0000_0001_0000;
+    const COMP_POL     : u16 = 0b0000_0000_0000_1000;
 }
 
 
diff --git a/tests/common/mod.rs b/tests/common/mod.rs
index 89b81c9..8ffd50e 100644
--- a/tests/common/mod.rs
+++ b/tests/common/mod.rs
@@ -22,6 +22,7 @@ impl BitFlags {
     pub const DR1          : u16 = 0b0000_0000_0100_0000;
     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 struct Config {
diff --git a/tests/tier2_i2c.rs b/tests/tier2_i2c.rs
index 1eb2871..5a3c950 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;
+use ads1x1x::{ ComparatorMode, ComparatorPolarity };
 
 #[macro_use]
 mod common;
@@ -21,12 +21,28 @@ macro_rules! test_set_comparator_mode {
     }
 }
 
-
 mod can_set_comparator_mode {
     use super::*;
     test_set_comparator_mode!(traditional, Traditional, Config::default().with_low( BitFlags::COMP_MODE));
     test_set_comparator_mode!(window,      Window,      Config::default().with_high(BitFlags::COMP_MODE));
 }
 
+macro_rules! test_set_comparator_pol {
+    ($name:ident, $variant:ident, $config:expr) => {
+        #[test]
+        fn $name() {
+            let transactions = [ I2cTrans::write(DEV_ADDR, vec![Register::CONFIG, $config.msb(), $config.lsb()]) ];
+            let mut dev = new_ads1014(&transactions);
+            dev.set_comparator_polarity(ComparatorPolarity::$variant).unwrap();
+            destroy_ads1014(dev);
+        }
+    }
+}
+
+mod can_set_comparator_polarity {
+    use super::*;
+    test_set_comparator_pol!(low,  ActiveLow,  Config::default().with_low( BitFlags::COMP_POL));
+    test_set_comparator_pol!(high, ActiveHigh, Config::default().with_high(BitFlags::COMP_POL));
+}