Fix voltmeter autorange never increasing range

Author: bessman

PSL/achan.py

@@ -231,7 +231,7 @@ def waveform_table(self) -> np.ndarray:
 
         The table contains 512 values.
         """
-        # A form of amplitude control. Max PWM duty cycle out of 512 clock  cycles.
+        # A form of amplitude control. Max PWM duty cycle out of 512 clock cycles.
         return self._range_normalize(self._waveform_table, 511)
 
     @waveform_table.setter

PSL/multimeter.py

@@ -87,6 +87,7 @@ def _measure_voltage(self, channel: str) -> float:
 
     def _voltmeter_autorange(self, channel: str) -> float:
         if channel in ("CH1", "CH2"):
+            self._set_gain(channel, 1)  # Reset gain.
             voltage = self._measure_voltage(channel)
 
             for gain in GAIN_VALUES[::-1]:

tests/recordings/multimeter/test_voltmeter_autorange.json

@@ -1 +1 @@
-[[[2], [8], [1], [0], [2], [8], [2], [0], [2], [10], [3], [2], [8], [1], [3]], [[], [], [], [1], [], [], [], [1], [], [], [111, 153, 1], [], [], [], [1]]]
+[[[2], [8], [1], [0], [2], [8], [2], [0], [2], [8], [1], [0], [2], [10], [3], [2], [8], [1], [7]], [[], [], [], [1], [], [], [], [1], [], [], [], [1], [], [], [71, 128, 1], [], [], [], [1]]]