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Diffstat (limited to 'decoders/onewire_link/__init__.py')
| -rw-r--r-- | decoders/onewire_link/__init__.py | 96 |
1 files changed, 53 insertions, 43 deletions
diff --git a/decoders/onewire_link/__init__.py b/decoders/onewire_link/__init__.py index 5c7251d..cb03471 100644 --- a/decoders/onewire_link/__init__.py +++ b/decoders/onewire_link/__init__.py @@ -19,63 +19,73 @@ ## ''' -1-Wire protocol decoder. +1-Wire protocol decoder (link layer). -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. -- Link layer (reset, presence detection, reading/writing bits) -- Network layer (skip/search/match device ROM addresses) -- Transport layer (transport data between 1-Wire master and device) +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: -Link layer + - Link layer (reset, presence detection, reading/writing bits) + - Network layer (skip/search/match device ROM addresses) + - Transport layer (transport data between 1-Wire master and device) + +Link layer protocol details: 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 +A sufficiently high samplerate is required to properly detect all the elements +of the protocol. A lower samplerate can be used if the master does not use +overdrive communication speed. The following minimal values should be used: + + - overdrive available: 2MHz minimum, 5MHz suggested + - overdrive not available: 400kHz minimum, 1MHz suggested 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) +separate signal used to deliver power to the bus during temperature conversion +as an example. This power signal is currently not used. + + - owr (1-Wire signal line) + - pwr (optional, dedicated power supply pin) 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, +1-Wire is an asynchronous protocol, so the decoder must know the samplerate. +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_slot (time for normal mode data slot) -- 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_slot (time for overdrive mode data slot) -- 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 +configure the following timing values (number of samplerate periods): + + - overdrive (if active the decoder will be prepared for overdrive) + - cnt_normal_bit (time for normal mode sample bit) + - cnt_normal_slot (time for normal mode data slot) + - 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_slot (time for overdrive mode data slot) + - cnt_overdrive_presence (time for overdrive mode sample presence) + - cnt_overdrive_reset (time for overdrive mode reset) + +These options should be configured only on very rare cases and the user should read the decoder source code to understand them correctly. +Protocol output format: +TODO. + Annotations: -Link layer annotations show the next events: -- NOTE/WARNING/ERROR - Possible sample rate related timing issues are reported. -- 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. -- BIT 0/1 - The event is marked from the signal negative edge to the end of the data - slot. The value of each received bit is also provided. + +Link layer annotations show the following events: + + - NOTE/WARNING/ERROR + Possible samplerate related timing issues are reported. + - Reset/presence true/false + The event is marked from the signal negative edge to the end of the reset + high period. It's also reported if there are any devices attached to the bus. + - Bit 0/1 + The event is marked from the signal negative edge to the end of the data + slot. The value of each received bit is also provided. TODO: -- check for protocol correctness, if events are timed inside prescribed limits -- maybe add support for interrupts, check if this feature is deprecated +- Check for protocol correctness, if events are timed inside prescribed limits. +- Maybe add support for interrupts, check if this feature is deprecated. ''' -from .onewire_link import * +from .onewire_link import * + |