diff options
Diffstat (limited to 'decoders/onewire')
| -rw-r--r-- | decoders/onewire/__init__.py | 38 | ||||
| -rw-r--r-- | decoders/onewire/onewire.py | 46 |
2 files changed, 58 insertions, 26 deletions
diff --git a/decoders/onewire/__init__.py b/decoders/onewire/__init__.py index 54eb65f..b58dde7 100644 --- a/decoders/onewire/__init__.py +++ b/decoders/onewire/__init__.py @@ -21,6 +21,44 @@ ''' 1-Wire protocol decoder. +The 1-Wire protocol enables bidirectional communication over a single wire (and +ground) between a single master and one or multiple slaves. The protocol is +layered, the provided parser decodes the next layers: +- Link layer (reset, presence detection, reading/writing bits) +- Network layer (skip, search, match device ROM addresses) +The higher layers (transport, presentation) are not decoded, since they are +mostly device specific and it would take a lot of code to interpret them. + +Probes: +1-Wire requires a single signal, but some master implementations might have a +separate signal use to deliver power to the bus during temperature conversion +as an example. This power signal is currently not parsed. +- owr (1-Wire bus) +- pwr (1-Wire power) + +Options: +1-Wire is an asynchronous protocol, so the decoder must know the sample rate. +The timing for sampling bits, presence and reset is calculated by the decoder, +but in case the user wishes to use different values, it is possible to +configure the next timing values (number of sample rate periods): +- overdrive (if active the decoder will be prepared for overdrive) +- cnt_normal_bit (time for normal mode sample bit) +- cnt_normal_presence (time for normal mode sample presence) +- cnt_normal_reset (time for normal mode reset) +- cnt_overdrive_bit (time for overdrive mode sample bit) +- cnt_overdrive_presence (time for overdrive mode sample presence) +- cnt_overdrive_reset (time for overdrive mode reset) +This options should be configured only on very rare cases and the user should +read the decoder source code to understand them correctly. + +Annotations: +Annotations can be shown for each layer of the protocol separately: +- link (the value of each transmitted bit is shown separately) +- network (the ROM command, and address are shown) +- transport (only transport layer byte transfers are shown) +If link layer annotations are shown, possible issues with sample rate and sample +timing are also shown. + TODO: - fix annotations to have event duration instead of begin end time - add CRC checks for network layer diff --git a/decoders/onewire/onewire.py b/decoders/onewire/onewire.py index 7cd840b..b8e5041 100644 --- a/decoders/onewire/onewire.py +++ b/decoders/onewire/onewire.py @@ -27,6 +27,16 @@ ANN_LINK = 0 ANN_NETWORK = 1 ANN_TRANSPORT = 2 +# a dictionary of ROM commands and their names +rom_command = {0x33: "READ ROM", + 0x0f: "CONDITIONAL READ ROM", + 0xcc: "SKIP ROM", + 0x55: "MATCH ROM", + 0xf0: "SEARCH ROM", + 0xec: "CONDITIONAL SEARCH ROM", + 0x3c: "OVERDRIVE SKIP ROM", + 0x6d: "OVERDRIVE MATCH ROM"} + class Decoder(srd.Decoder): api_version = 1 id = 'onewire' @@ -207,7 +217,7 @@ class Decoder(srd.Decoder): raise Exception('Invalid lnk_state: %d' % self.lnk_state) # Network layer - + # State machine. if (self.lnk_event == "RESET"): self.net_state = "COMMAND" @@ -218,39 +228,23 @@ class Decoder(srd.Decoder): elif (self.net_state == "COMMAND"): # Receiving and decoding a ROM command if (self.onewire_collect(8)): - self.put(self.net_beg, self.net_end, self.out_ann, [ANN_NETWORK, ['ROM COMMAND: 0x%02x' % self.net_data]]) - if (self.net_data == 0x33): - # READ ROM - self.put(self.net_beg, self.net_end, self.out_ann, [ANN_NETWORK, ['ROM COMMAND: \'READ ROM\'']]) + self.put(self.net_beg, self.net_end, self.out_ann, [ANN_NETWORK, ['ROM COMMAND: 0x%02x \'%s\'' % (self.net_data, rom_command[self.net_data])]]) + if (self.net_data == 0x33): # READ ROM self.net_state = "GET ROM" - elif (self.net_data == 0x0f): - # CONDITIONAL READ ROM - self.put(self.net_beg, self.net_end, self.out_ann, [ANN_NETWORK, ['ROM COMMAND: \'CONDITIONAL READ ROM\'']]) + elif (self.net_data == 0x0f): # CONDITIONAL READ ROM self.net_state = "GET ROM" - elif (self.net_data == 0xcc): - # SKIP ROM - self.put(self.net_beg, self.net_end, self.out_ann, [ANN_NETWORK, ['ROM COMMAND: \'SKIP ROM\'']]) + elif (self.net_data == 0xcc): # SKIP ROM self.net_state = "TRANSPORT" - elif (self.net_data == 0x55): - # MATCH ROM - self.put(self.net_beg, self.net_end, self.out_ann, [ANN_NETWORK, ['ROM COMMAND: \'MATCH ROM\'']]) + elif (self.net_data == 0x55): # MATCH ROM self.net_state = "GET ROM" - elif (self.net_data == 0xf0): - # SEARCH ROM - self.put(self.net_beg, self.net_end, self.out_ann, [ANN_NETWORK, ['ROM COMMAND: \'SEARCH ROM\'']]) + elif (self.net_data == 0xf0): # SEARCH ROM self.net_state = "SEARCH ROM" - elif (self.net_data == 0xec): - # CONDITIONAL SEARCH ROM - self.put(self.net_beg, self.net_end, self.out_ann, [ANN_NETWORK, ['ROM COMMAND: \'CONDITIONAL SEARCH ROM\'']]) + elif (self.net_data == 0xec): # CONDITIONAL SEARCH ROM self.net_state = "SEARCH ROM" - elif (self.net_data == 0x3c): - # OVERDRIVE SKIP ROM - self.put(self.net_beg, self.net_end, self.out_ann, [ANN_NETWORK, ['ROM COMMAND: \'OVERDRIVE SKIP ROM\'']]) + elif (self.net_data == 0x3c): # OVERDRIVE SKIP ROM self.lnk_overdrive = 1 self.net_state = "TRANSPORT" - elif (self.net_data == 0x69): - # OVERDRIVE MATCH ROM - self.put(self.net_beg, self.net_end, self.out_ann, [ANN_NETWORK, ['ROM COMMAND: \'OVERDRIVE MATCH ROM\'']]) + elif (self.net_data == 0x69): # OVERDRIVE MATCH ROM self.lnk_overdrive = 1 self.net_state = "GET ROM" elif (self.net_state == "GET ROM"): |