Use Future to obtain voltage of build HAT

Author: chrisruk

buildhat/hat.py

@@ -1,5 +1,7 @@
 """HAT handling functionality"""
 
+from concurrent.futures import Future
+
 from .devices import Device
 
 
@@ -45,11 +47,10 @@ def get_vin(self):
         :return: Voltage on the input power jack
         :rtype: float
         """
+        ftr = Future()
+        Device._instance.vincond.append(ftr)
         Device._instance.write(b"vin\r")
-        with Device._instance.vincond:
-            Device._instance.vincond.wait()
-
-        return Device._instance.vin
+        return ftr.result()
 
     def _set_led(self, intmode):
         if isinstance(intmode, int) and intmode >= -1 and intmode <= 3:

buildhat/serinterface.py

@@ -87,10 +87,9 @@ def __init__(self, firmware, signature, version, device="/dev/serial0", debug=Fa
         self.portcond = []
         self.pulsecond = []
         self.rampcond = []
+        self.vincond = []
         self.fin = False
         self.running = True
-        self.vincond = Condition()
-        self.vin = None
         if debug:
             tmp = tempfile.NamedTemporaryFile(suffix=".log", prefix="buildhat-", delete=False)
             logging.basicConfig(filename=tmp.name, format='%(asctime)s %(message)s',
@@ -388,6 +387,5 @@ def runit():
 
             if len(line) >= 5 and line[1] == "." and line.endswith(" V"):
                 vin = float(line.split(" ")[0])
-                self.vin = vin
-                with self.vincond:
-                    self.vincond.notify()
+                ftr = self.vincond.pop()
+                ftr.set_result(vin)