Additional support for PicoScope 4444 (#151)

* Ported fix for USB power from ps5000a to ps4000a.
Enabled Bandwidth Filtering for PicoScope 4444

* Corrected PEP8 violations

Author: rascustoms

picoscope/picobase.py

@@ -247,10 +247,14 @@ def setChannel(self, channel='A', coupling="AC", VRange=2.0,
         if not isinstance(BWLimited, int):
             BWLimited = self.BW_LIMITS[BWLimited]
 
-        if BWLimited == 2:
-            BWLimited = 2  # Bandwidth Limiter for PicoScope 6404
+        if BWLimited == 3:
+            BWLimited = 3  # 1MHz Bandwidth Limiter for PicoScope 4444
+        elif BWLimited == 2:
+            BWLimited = 2  # Bandwidth Limiter for PicoScope 6404,
+            # 100kHz Bandwidth Limiter for PicoScope 4444
         elif BWLimited == 1:
-            BWLimited = 1  # Bandwidth Limiter for PicoScope 6402/6403
+            BWLimited = 1  # Bandwidth Limiter for PicoScope 6402/6403,
+            # 20kHz Bandwidth Limiter for PicoScope 4444
         else:
             BWLimited = 0
 

picoscope/ps4000a.py

@@ -145,9 +145,19 @@ def _lowLevelOpenUnit(self, sn):
             serialNullTermStr = None
         # Passing None is the same as passing NULL
         m = self.lib.ps4000aOpenUnit(byref(c_handle), serialNullTermStr)
-        self.checkResult(m)
         self.handle = c_handle.value
 
+        # This will check if the power supply is not connected
+        # and change the power supply accordingly
+        # Personally (me = Mark), I don't like this
+        # since the user should address this immediately, and we
+        # shouldn't let this go as a soft error
+        # but I think this should do for now
+        if m == 0x11A:
+            self.changePowerSource(m)
+        else:
+            self.checkResult(m)
+
         self.model = self.getUnitInfo('VariantInfo')
 
     def _lowLevelOpenUnitAsync(self, sn):
@@ -216,6 +226,11 @@ def _lowLevelSetChannel(self, chNum, enabled, coupling, VRange, VOffset,
                                        c_enum(VRange), c_float(VOffset))
         self.checkResult(m)
 
+        m = self.lib.ps4000aSetBandwidthFilter(c_int16(self.handle),
+                                               c_enum(chNum),
+                                               c_enum(BWLimited))
+        self.checkResult(m)
+
     def _lowLevelStop(self):
         m = self.lib.ps4000aStop(c_int16(self.handle))
         self.checkResult(m)
@@ -406,6 +421,12 @@ def _lowLevelSetDeviceResolution(self, resolution):
             c_enum(resolution))
         self.checkResult(m)
 
+    def _lowLevelChangePowerSource(self, powerstate):
+        m = self.lib.ps4000aChangePowerSource(
+            c_int16(self.handle),
+            c_enum(powerstate))
+        self.checkResult(m)
+
     def _lowLevelGetValuesBulk(self, numSamples, fromSegment, toSegment,
                                downSampleRatio, downSampleMode, overflow):
         """Copy data from several memory segments at once."""