uart: Implement signal inversion

[libsigrokdecode.git] / decoders / uart / pd.py

diff --git a/decoders/uart/pd.py b/decoders/uart/pd.py
index 63ea50d853f6b8e23ae853a3dafa45297a99bdf8..b8508a72c74b7338e7a1039ce6e265e84badda2c 100644 (file)
--- a/decoders/uart/pd.py
+++ b/decoders/uart/pd.py
@@ -70,6 +70,9 @@ def parity_ok(parity_type, parity_bit, data, num_data_bits):
 class SamplerateError(Exception):
     pass
 
+class ChannelError(Exception):
+    pass
+
 class Decoder(srd.Decoder):
     api_version = 2
     id = 'uart'
@@ -99,7 +102,10 @@ class Decoder(srd.Decoder):
             'values': ('lsb-first', 'msb-first')},
         {'id': 'format', 'desc': 'Data format', 'default': 'ascii',
             'values': ('ascii', 'dec', 'hex', 'oct', 'bin')},
-        # TODO: Options to invert the signal(s).
+        {'id': 'invert_rx', 'desc': 'Invert RX?', 'default': 'no',
+            'values': ('yes', 'no')},
+        {'id': 'invert_tx', 'desc': 'Invert TX?', 'default': 'no',
+            'values': ('yes', 'no')},
     )
     annotations = (
         ('rx-data', 'RX data'),
@@ -173,7 +179,7 @@ class Decoder(srd.Decoder):
 
     def metadata(self, key, value):
         if key == srd.SRD_CONF_SAMPLERATE:
-            self.samplerate = value;
+            self.samplerate = value
             # The width of one UART bit in number of samples.
             self.bit_width = float(self.samplerate) / float(self.options['baudrate'])
 
@@ -333,10 +339,15 @@ class Decoder(srd.Decoder):
             #     continue
             self.oldpins, (rx, tx) = pins, pins
 
+            if self.options['invert_rx'] == 'yes':
+                rx = not rx
+            if self.options['invert_tx'] == 'yes':
+                tx = not tx
+
             # Either RX or TX (but not both) can be omitted.
             has_pin = [rx in (0, 1), tx in (0, 1)]
             if has_pin == [False, False]:
-                raise Exception('Either TX or RX (or both) pins required.')
+                raise ChannelError('Either TX or RX (or both) pins required.')
 
             # State machine.
             for rxtx in (RX, TX):
@@ -359,4 +370,3 @@ class Decoder(srd.Decoder):
 
                 # Save current RX/TX values for the next round.
                 self.oldbit[rxtx] = signal
-