From ad572b64eb0e99f269297d8de19d709ef66d3f24 Mon Sep 17 00:00:00 2001
From: Diego Barrios Romero <eldruin@gmail.com>
Date: Tue, 20 Nov 2018 20:24:21 +0100
Subject: Add function to use the ALERT/RDY pin as conversion-ready pin

---
 README.md                     |  1 +
 src/devices/features/tier2.rs | 15 +++++++++++++++
 src/lib.rs                    |  2 ++
 tests/tier2_i2c.rs            | 23 +++++++++++++++++++++++
 4 files changed, 41 insertions(+)

diff --git a/README.md b/README.md
index e64e557..f471bb5 100644
--- a/README.md
+++ b/README.md
@@ -25,6 +25,7 @@ This driver allows you to:
 - Set the comparator latching. See: `set_comparator_latching()`.
 - Set the comparator queue. See: `set_comparator_queue()`.
 - Disable the comparator. See: `disable_comparator()`.
+- Set the ALERT/RDY pin to be used as conversion-ready pin. See: `use_alert_rdy_pin_as_ready()`.
 
 ## The devices
 
diff --git a/src/devices/features/tier2.rs b/src/devices/features/tier2.rs
index 79843f6..6047572 100644
--- a/src/devices/features/tier2.rs
+++ b/src/devices/features/tier2.rs
@@ -115,4 +115,19 @@ where
         self.config = config;
         Ok(())
     }
+
+    /// Use the ALERT/RDY pin as conversion-ready pin.
+    ///
+    /// This the ALERT/RDY pin outputs the OS bit when in OneShot mode, and
+    /// provides a continuous-conversion ready pulse when in
+    /// continuous-conversion mode.
+    ///
+    /// When calling this the comparator will be disabled and the thresholds will be cleared.
+    pub fn use_alert_rdy_pin_as_ready(&mut self) -> Result<(), Error<E>> {
+        if self.config != self.config.with_high(BitFlags::COMP_QUE1).with_high(BitFlags::COMP_QUE0) {
+            self.disable_comparator()?;
+        }
+        self.iface.write_register(Register::HIGH_TH, 0x8000)?;
+        self.iface.write_register(Register::LOW_TH, 0)
+    }
 }
diff --git a/src/lib.rs b/src/lib.rs
index fd4181e..5e94b43 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -17,6 +17,7 @@
 //! - Set the comparator latching. See: [`set_comparator_latching()`].
 //! - Set the comparator queue. See: [`set_comparator_queue()`].
 //! - Disable the comparator. See: [`disable_comparator()`].
+//! - Set the ALERT/RDY pin to be used as conversion-ready pin. See: [`use_alert_rdy_pin_as_ready()`].
 //!
 //! [`into_continuous()`]: struct.Ads1x1x.html#method.into_continuous
 //! [read_os]: struct.Ads1x1x.html#method.read
@@ -30,6 +31,7 @@
 //! [`set_comparator_latching()`]: struct.Ads1x1x.html#method.set_comparator_latching
 //! [`set_comparator_queue()`]: struct.Ads1x1x.html#method.set_comparator_queue
 //! [`disable_comparator()`]: struct.Ads1x1x.html#method.disable_comparator
+//! [`use_alert_rdy_pin_as_ready()`]: struct.Ads1x1x.html#method.use_alert_rdy_pin_as_ready
 //!
 //! ## The devices
 //!
diff --git a/tests/tier2_i2c.rs b/tests/tier2_i2c.rs
index 7d17270..4e43e90 100644
--- a/tests/tier2_i2c.rs
+++ b/tests/tier2_i2c.rs
@@ -67,6 +67,29 @@ mod can_set_comparator_queue {
     config_test!(four, set_comparator_queue, ComparatorQueue::Four, Config::default().with_high(BitFlags::COMP_QUE1).with_low( BitFlags::COMP_QUE0));
 }
 
+#[test]
+fn can_use_alert_rdy_pin_as_rdy_does_not_disable_comparator_if_already_disabled() {
+    let transactions = [ I2cTrans::write(DEV_ADDR, vec![Register::HIGH_TH, 0b1000_0000, 0]),
+                         I2cTrans::write(DEV_ADDR, vec![Register::LOW_TH,  0,    0]), ];
+    let mut dev = new_ads1014(&transactions);
+    dev.use_alert_rdy_pin_as_ready().unwrap();
+    destroy_ads1014(dev);
+}
+
+#[test]
+fn can_use_alert_rdy_pin_as_rdy_disabled_comparator() {
+    let config = Config::default().with_low(BitFlags::COMP_QUE1).with_low(BitFlags::COMP_QUE0);
+    let config_disabled_comp = Config::default().with_high(BitFlags::COMP_QUE1).with_high(BitFlags::COMP_QUE0);
+    let transactions = [ I2cTrans::write(DEV_ADDR, vec![Register::CONFIG, config.msb(), config.lsb()]),
+                         I2cTrans::write(DEV_ADDR, vec![Register::CONFIG, config_disabled_comp.msb(), config_disabled_comp.lsb()]),
+                         I2cTrans::write(DEV_ADDR, vec![Register::HIGH_TH, 0b1000_0000, 0]),
+                         I2cTrans::write(DEV_ADDR, vec![Register::LOW_TH,  0,    0]), ];
+    let mut dev = new_ads1014(&transactions);
+    dev.set_comparator_queue(ComparatorQueue::One).unwrap();
+    dev.use_alert_rdy_pin_as_ready().unwrap();
+    destroy_ads1014(dev);
+}
+
 mod can_set_full_scale_range {
     use super::*;
     config_test!(fsr6,   set_full_scale_range, FullScaleRange::Within6_144V, Config::default().with_low( BitFlags::PGA2).with_low( BitFlags::PGA1).with_low( BitFlags::PGA0));
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