From e6a3d9badd02b6082e1a718ac7f0fa18e976a191 Mon Sep 17 00:00:00 2001
From: Danilo Bargen <mail@dbrgn.ch>
Date: Wed, 5 Aug 2020 23:35:09 +0200
Subject: [PATCH] Expose factory calibration data

Verified to be working on an STM32L071KBTx. As a cross-check, I verified
the memory addresses against the datasheet of the (randomly picked)
STM32L053C6, they match.
---
 src/calibration.rs | 88 ++++++++++++++++++++++++++++++++++++++++++++++
 src/lib.rs         |  1 +
 2 files changed, 89 insertions(+)
 create mode 100644 src/calibration.rs

diff --git a/src/calibration.rs b/src/calibration.rs
new file mode 100644
index 00000000..32212803
--- /dev/null
+++ b/src/calibration.rs
@@ -0,0 +1,88 @@
+//! Factory-programmed calibration data
+//!
+//! The STM32L0 contains a few read-only registers with factory calibration
+//! data that are written during production.
+
+macro_rules! define_ptr_type {
+    ($name: ident, $ptr: expr) => {
+        impl $name {
+            fn ptr() -> *const Self {
+                $ptr as *const _
+            }
+
+            /// Returns a wrapped reference to the value in flash memory
+            pub fn get() -> &'static Self {
+                unsafe { &*Self::ptr() }
+            }
+        }
+    };
+}
+
+/// Internal voltage reference calibration data (VREFINT_CAL)
+///
+/// The internal voltage reference provides a stable (bandgap) voltage output
+/// for the ADC and Comparators. The precise voltage of V_REFINT is
+/// individually measured for each part by ST during production test and stored
+/// in the system memory area. It can be accessed through this struct.
+#[derive(Debug)]
+#[repr(C)]
+pub struct VrefintCal(u16);
+define_ptr_type!(VrefintCal, 0x1FF8_0078);
+impl VrefintCal {
+    /// Read calibration value (VREFINT_CAL), acquired at temperature of 25 °C and V_DDA = 3 V.
+    pub fn read(&self) -> u16 {
+        self.0
+    }
+}
+
+/// Temperature sensor calibration data acquired at 30 °C (TS_CAL1)
+///
+/// The temperature sensor (T_SENSE) generates a voltage (V_SENSE) that varies
+/// linearly with temperature.
+///
+/// The sensor provides good linearity, but it has to be calibrated to obtain
+/// good overall accuracy of the temperature measurement. As the offset of the
+/// temperature sensor varies from chip to chip due to process variation, the
+/// uncalibrated internal temperature sensor is suitable for applications that
+/// detect temperature changes only.
+///
+/// To improve the accuracy of the temperature sensor measurement, each device
+/// is individually factory-calibrated by ST. The temperature sensor factory
+/// calibration data are stored by ST in the system memory area and can be
+/// accessed through this struct.
+#[derive(Debug)]
+#[repr(C)]
+pub struct VtempCal30(u16);
+define_ptr_type!(VtempCal30, 0x1FF8_007A);
+impl VtempCal30 {
+    /// Read calibration value (TS_CAL1), acquired at temperature of 30 °C and V_DDA = 3 V.
+    pub fn read(&self) -> u16 {
+        self.0
+    }
+}
+
+/// Temperature sensor calibration data acquired at 130 °C (TS_CAL2)
+///
+/// The temperature sensor (T_SENSE) generates a voltage (V_SENSE) that varies
+/// linearly with temperature.
+///
+/// The sensor provides good linearity, but it has to be calibrated to obtain
+/// good overall accuracy of the temperature measurement. As the offset of the
+/// temperature sensor varies from chip to chip due to process variation, the
+/// uncalibrated internal temperature sensor is suitable for applications that
+/// detect temperature changes only.
+///
+/// To improve the accuracy of the temperature sensor measurement, each device
+/// is individually factory-calibrated by ST. The temperature sensor factory
+/// calibration data are stored by ST in the system memory area and can be
+/// accessed through this struct.
+#[derive(Debug)]
+#[repr(C)]
+pub struct VtempCal130(u16);
+define_ptr_type!(VtempCal130, 0x1FF8_007E);
+impl VtempCal130 {
+    /// Read calibration value (TS_CAL2), acquired at temperature of 130 °C and V_DDA = 3 V.
+    pub fn read(&self) -> u16 {
+        self.0
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 6d151707..909b51b2 100755
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -17,6 +17,7 @@ pub use stm32l0::stm32l0x3 as pac;
 
 pub mod adc;
 pub mod aes;
+pub mod calibration;
 pub mod delay;
 pub mod dma;
 pub mod exti;