]> sigrok.org Git - libsigrokdecode.git/blobdiff - decoders/usb_signalling/pd.py
usb_signalling: decode RESET and Keep-Alive signalling conditions
[libsigrokdecode.git] / decoders / usb_signalling / pd.py
index 8e9723e6f6932e584988446cbbd099af7dff4af5..e0fd2916acbf0cab5166c6caacdf18664abeeb88 100644 (file)
@@ -34,6 +34,8 @@ Packet:
  - 'STUFF BIT', None
  - 'EOP', None
  - 'ERR', None
+ - 'KEEP ALIVE', None
+ - 'RESET', None
 
 <sym>:
  - 'J', 'K', 'SE0', or 'SE1'
@@ -104,28 +106,29 @@ class Decoder(srd.Decoder):
         ('bit', 'Bit'),
         ('stuffbit', 'Stuff bit'),
         ('error', 'Error'),
+        ('keep-alive', 'Low-speed keep-alive'),
+        ('reset', 'Reset'),
     )
     annotation_rows = (
-        ('bits', 'Bits', (4, 5, 6, 7, 8)),
+        ('bits', 'Bits', (4, 5, 6, 7, 8, 9, 10)),
         ('symbols', 'Symbols', (0, 1, 2, 3)),
     )
 
     def __init__(self):
         self.samplerate = None
         self.oldsym = 'J' # The "idle" state is J.
-        self.ss_sop = None
         self.ss_block = None
         self.samplenum = 0
-        self.syms = []
         self.bitrate = None
         self.bitwidth = None
         self.samplepos = None
         self.samplenum_target = None
         self.samplenum_edge = None
+        self.samplenum_lastedge = 0
         self.oldpins = None
         self.edgepins = None
         self.consecutive_ones = 0
-        self.state = 'IDLE'
+        self.state = 'INIT'
 
     def start(self):
         self.out_python = self.register(srd.OUTPUT_PYTHON)
@@ -136,49 +139,49 @@ class Decoder(srd.Decoder):
             self.samplerate = value
             self.bitrate = bitrates[self.options['signalling']]
             self.bitwidth = float(self.samplerate) / float(self.bitrate)
-            self.halfbit = int(self.bitwidth / 2)
 
     def putpx(self, data):
-        self.put(self.samplenum, self.samplenum, self.out_python, data)
+        s = self.samplenum_edge
+        self.put(s, s, self.out_python, data)
 
     def putx(self, data):
-        self.put(self.samplenum, self.samplenum, self.out_ann, data)
+        s = self.samplenum_edge
+        self.put(s, s, self.out_ann, data)
 
     def putpm(self, data):
-        s, h = self.samplenum, self.halfbit
-        self.put(self.ss_block - h, s + h, self.out_python, data)
+        e = self.samplenum_edge
+        self.put(self.ss_block, e, self.out_python, data)
 
     def putm(self, data):
-        s, h = self.samplenum, self.halfbit
-        self.put(self.ss_block - h, s + h, self.out_ann, data)
+        e = self.samplenum_edge
+        self.put(self.ss_block, e, self.out_ann, data)
 
     def putpb(self, data):
-        s, h = self.samplenum, self.halfbit
-        self.put(self.samplenum_edge, s + h, self.out_python, data)
+        s, e = self.samplenum_lastedge, self.samplenum_edge
+        self.put(s, e, self.out_python, data)
 
     def putb(self, data):
-        s, h = self.samplenum, self.halfbit
-        self.put(self.samplenum_edge, s + h, self.out_ann, data)
+        s, e = self.samplenum_lastedge, self.samplenum_edge
+        self.put(s, e, self.out_ann, data)
 
     def set_new_target_samplenum(self):
         self.samplepos += self.bitwidth;
         self.samplenum_target = int(self.samplepos)
+        self.samplenum_lastedge = self.samplenum_edge
         self.samplenum_edge = int(self.samplepos - (self.bitwidth / 2))
 
     def wait_for_sop(self, sym):
         # Wait for a Start of Packet (SOP), i.e. a J->K symbol change.
-        if sym != 'K':
-            self.oldsym = sym
+        if sym != 'K' or self.oldsym != 'J':
             return
         self.consecutive_ones = 0
-        self.ss_sop = self.samplenum
-        self.samplepos = self.ss_sop - (self.bitwidth / 2) + 0.5
+        self.samplepos = self.samplenum - (self.bitwidth / 2) + 0.5
         self.set_new_target_samplenum()
         self.putpx(['SOP', None])
         self.putx([4, ['SOP', 'S']])
         self.state = 'GET BIT'
 
-    def handle_bit(self, sym, b):
+    def handle_bit(self, b):
         if self.consecutive_ones == 6:
             if b == '0':
                 # Stuff bit.
@@ -200,28 +203,33 @@ class Decoder(srd.Decoder):
 
     def get_eop(self, sym):
         # EOP: SE0 for >= 1 bittime (usually 2 bittimes), then J.
-        self.syms.append(sym)
+        self.set_new_target_samplenum()
         self.putpb(['SYM', sym])
         self.putb(sym_annotation[sym])
-        self.set_new_target_samplenum()
         self.oldsym = sym
-        if self.syms[-2:] == ['SE0', 'J']:
+        if sym == 'SE0':
+            pass
+        elif sym == 'J':
             # Got an EOP.
             self.putpm(['EOP', None])
             self.putm([5, ['EOP', 'E']])
-            self.syms, self.state = [], 'IDLE'
+            self.state = 'IDLE'
             self.bitwidth = float(self.samplerate) / float(self.bitrate)
+        else:
+            self.putpm(['ERR', None])
+            self.putm([8, ['EOP Error', 'EErr', 'E']])
+            self.state = 'IDLE'
 
     def get_bit(self, sym):
+        self.set_new_target_samplenum()
         if sym == 'SE0':
-            # Start of an EOP. Change state, run get_eop() for this bit.
+            # Start of an EOP. Change state, save edge
             self.state = 'GET EOP'
-            self.ss_block = self.samplenum
-            self.get_eop(sym)
-            return
-        self.syms.append(sym)
+            self.ss_block = self.samplenum_lastedge
+        else:
+            b = '0' if self.oldsym != sym else '1'
+            self.handle_bit(b)
         self.putpb(['SYM', sym])
-        b = '0' if self.oldsym != sym else '1'
         self.putb(sym_annotation[sym])
         if self.oldsym != sym:
             edgesym = symbols[self.options['signalling']][tuple(self.edgepins)]
@@ -232,10 +240,19 @@ class Decoder(srd.Decoder):
                 else:
                     self.bitwidth = self.bitwidth + (0.001 * self.bitwidth)
                     self.samplepos = self.samplepos + (0.01 * self.bitwidth)
-        self.handle_bit(sym, b)
-        self.set_new_target_samplenum()
         self.oldsym = sym
 
+    def handle_idle(self, sym):
+        self.samplenum_edge = self.samplenum
+        se0_length = float(self.samplenum - self.samplenum_lastedge) / self.samplerate
+        if se0_length > 2.5e-6: # 2.5us
+            self.putpb(['RESET', None])
+            self.putb([10, ['Reset', 'Res', 'R']])
+        elif se0_length > 1.2e-6 and self.options['signalling'] == 'low-speed':
+            self.putpb(['KEEP ALIVE', None])
+            self.putb([9, ['Keep-alive', 'KA', 'A']])
+        self.state = 'IDLE'
+
     def decode(self, ss, es, data):
         if not self.samplerate:
             raise SamplerateError('Cannot decode without samplerate.')
@@ -247,7 +264,11 @@ class Decoder(srd.Decoder):
                     continue
                 self.oldpins = pins
                 sym = symbols[self.options['signalling']][tuple(pins)]
-                self.wait_for_sop(sym)
+                if sym == 'SE0':
+                    self.samplenum_lastedge = self.samplenum
+                    self.state = 'WAIT IDLE'
+                else:
+                    self.wait_for_sop(sym)
                 self.edgepins = pins
             elif self.state in ('GET BIT', 'GET EOP'):
                 # Wait until we're in the middle of the desired bit.
@@ -260,3 +281,17 @@ class Decoder(srd.Decoder):
                     self.get_bit(sym)
                 elif self.state == 'GET EOP':
                     self.get_eop(sym)
+            elif self.state == 'WAIT IDLE':
+                if self.oldpins == pins:
+                    continue
+                sym = symbols[self.options['signalling']][tuple(pins)]
+                if self.samplenum - self.samplenum_lastedge > 1:
+                    self.handle_idle(sym)
+                else:
+                    self.wait_for_sop(sym)
+                self.oldpins = pins
+                self.edgepins = pins
+            elif self.state == 'INIT':
+                sym = symbols[self.options['signalling']][tuple(pins)]
+                self.handle_idle(sym)
+                self.oldpins = pins