diff options
| -rw-r--r-- | decoders/parallel/__init__.py | 27 |
1 files changed, 19 insertions, 8 deletions
diff --git a/decoders/parallel/__init__.py b/decoders/parallel/__init__.py index 100523e..e7ed36c 100644 --- a/decoders/parallel/__init__.py +++ b/decoders/parallel/__init__.py @@ -19,16 +19,27 @@ ''' This protocol decoder can decode synchronous parallel buses with various -number of data bits/channels and one (optional) clock line. +data bits/channels counts, an (optional) clock line, and an (optional) +select/enable/reset line. -If no clock line is supplied, the decoder works slightly differently in -that it interprets every transition on any of the supplied data channels -like there had been a clock transition. +Data bits are taken from the decoder's lowest connected input pins. The +input signal's data lines count need not span the full amount of the +decoder's maximum supported data lines count. Not connected data lines +are assumed to be low. -It is required to use the lowest data channels, and use consecutive ones. -For example, for a 4-bit sync parallel bus, channels D0/D1/D2/D3 (and CLK) -should be used. Using combinations like D7/D12/D3/D15 is not supported. -For an 8-bit bus you should use D0-D7, for a 16-bit bus use D0-D15 and so on. +Example use cases are: Connect D3/D2/D1/D0 (and CLK) to a 4-bit bus. +Connect D7 and D6 to inspect the two most significant bits of an 8-bit +bus (and have 8-bit values shown instead of just 2-bit values). + +When provided, the specified clock edge determines when data lines get +sampled. Without a clock spec, each transition on any of the data lines +will be shown, which can become busy/noisy depending on the input data. + +Another signal optionally can control the period of time within which +the data lines' bit pattern gets interpreted. Typical use cases would be +reset, or select, or enable signals that are related to the bus' data +communication. This optional signal can also improve synchronization to +wider payload data which spans several bus cycles (multiplexing). ''' from .pd import Decoder |