chore(spo2): Small app cleanup

preload/apps/spo2/__init__.py

@@ -40,8 +40,8 @@ class SPO2:
             # don't update on every callback
             if self.update_screen >= self.DRAW_AFTER_SAMPLES:
                 self.disp.clear(self.COLOR_BACKGROUND)
-                self.draw_histogram(self.ir_history, color.RED)
-                self.draw_histogram(self.red_history, color.GREEN)
+                self.draw_history(self.ir_history, color.RED)
+                self.draw_history(self.red_history, color.GREEN)
                 spo2, spo2_valid, hr, hr_valid = spo2_algo.maxim_rd117(
                     self.ir_history, self.red_history
                 )
@@ -76,12 +76,6 @@ class SPO2:
 
         # 4x over sampling is active ATM
         self.sensor = max86150.MAX86150(callback=callback, sample_rate=self.RATE * 4)
-        while True:
-            utime.sleep(0.1)
-            if buttons.read(buttons.BOTTOM_RIGHT):
-                pass
-            while buttons.read(buttons.BOTTOM_RIGHT):
-                pass
 
     def update_history(self, datasets):
         for val in datasets:
@@ -121,7 +115,7 @@ class SPO2:
         self.ir_history = self.ir_history[-self.HISTORY_MAX :]
         self.red_history = self.red_history[-self.HISTORY_MAX :]
 
-    def draw_histogram(self, history, col):
+    def draw_history(self, history, col):
         # offset in pause_histogram mode
         window_end = len(history) - self.histogram_offset
         s_start = max(0, window_end - (self.RATE * 2))
@@ -156,3 +150,10 @@ if __name__ == "__main__":
     except KeyboardInterrupt as e:
         sensor.close()
         raise e
+
+    while True:
+        utime.sleep(0.1)
+        if buttons.read(buttons.BOTTOM_RIGHT):
+            pass
+        while buttons.read(buttons.BOTTOM_RIGHT):
+            pass