Add methods to control SLEEPDEEP bit

Close #68

Author: hannobraun

src/peripheral/scb.rs

@@ -580,3 +580,21 @@ impl SCB {
         ::asm::isb();
     }
 }
+
+const SCB_SCR_SLEEPDEEP: u32 = 0x1 << 2;
+
+impl SCB {
+    /// Set the SLEEPDEEP bit in the SCR register
+    pub fn set_sleepdeep(&mut self) {
+        unsafe {
+            self.scr.modify(|scr| scr | SCB_SCR_SLEEPDEEP);
+        }
+    }
+
+    /// Clear the SLEEPDEEP bit in the SCR register
+    pub fn clear_sleepdeep(&mut self) {
+        unsafe {
+            self.scr.modify(|scr| scr & !SCB_SCR_SLEEPDEEP);
+        }
+    }
+}