Fix and reduction of undervoltage only

check_raspi_voltage

@@ -4,6 +4,19 @@ import argparse
 import nagios
 import subprocess
 
+"""
+Bit	Hex     Value Meaning
+0	1	    Under-voltage detected
+1	2	    ARM frequency has been caped
+2	4	    Currently throttled
+3	8	    Soft temperature limit is active
+16	1000	Under-voltage has occurred
+17	2000	ARM frequency capping has occurred
+18	4000	Throttling has occurred
+19	8000	Soft temperature limit has occurred
+
+Bit16+ are resetted with a reboot (only)
+"""
 
 if __name__ == "__main__":
     throttled = subprocess.check_output(['vcgencmd', 'get_throttled']).decode('utf-8')
@@ -12,15 +25,15 @@ if __name__ == "__main__":
         tval = int(tval, 16)
     except ValueError:
         tval = None
+    else:
+        tval &= 0x3fff  # remove the values which are only resetted with a reboot
     #
     n = nagios.Nagios()
     #
     if tval is None:
         status = n.UNKNOWN
-    elif tval & 0x4000 != 0:
+    elif tval & 0x1 != 0:
         status = n.ERROR
-    elif tval != 0:
-        status = n.WARNING
     else:
         status = n.OK
     #