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Diffstat (limited to 'decoders/onewire_transport/__init__.py')
| -rw-r--r-- | decoders/onewire_transport/__init__.py | 62 |
1 files changed, 21 insertions, 41 deletions
diff --git a/decoders/onewire_transport/__init__.py b/decoders/onewire_transport/__init__.py index 28db017..3b9577e 100644 --- a/decoders/onewire_transport/__init__.py +++ b/decoders/onewire_transport/__init__.py @@ -23,54 +23,34 @@ 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: +layered. - 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. +- Network layer (skip/search/match device ROM addresses) +- Transport layer (transfer data between 1-Wire master and device) -Sample rate: -A high enough sample rate is required to properly detect all the elements of -the protocol. A lower sample rate can be used if the master does not use -overdrive communication speed. The next minimal values should be used: -- overdrive available: 2MHz minimum, 5MHz suggested -- overdrive not available: 400kHz minimum, 1MHz suggested +Transport layer -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. +The transport layer is the largest and most complex part of the protocol, since +it is very device specific. The decoder is parsing only a small part of the +protocol. 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. +The next link layer annotations are shown: +- RESET/PRESENCE True/False + The event is marked from the signal negative edge to the end of the reset + high period. It is also reported if there are any devices attached to the + bus. +The next network layer annotations are shown: +- ROM val + The 64bit value of the addressed device is displayed: + family code (1B) + serial number (6B) + CRC (1B) +- FUNCTION COMMAND val name + The requested FUNCTION command is displayed as an 8bit HEX value and by name. +- DATA val + Data intended for the transport layer is displayed as an 8bit HEX value. TODO: -- add CRC checks for network layer -- add transport layer code -- review link layer code, to check for protocol correctness -- define output protocol +- add CRC checks for transport layer ''' from .onewire_transport import * |