Curtiss-Wright FHF5-PC4MWB04-00, Справочник по аппаратуре

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FPDP PRIMER
Copyright 2017 9-4 FibreXtreme Hardware Reference
9.3.2 Data Framing
The FPDP specification does not allow for the transmission of address information.
However, many systems have data coming from several cards or channels. The way to
identify data from each channel is through framing. A synchronization pulse signal,
/SYNC, was defined for framing purposes. The frame size is defined as the number of data
items in the frame. Unframed data may also be transmitted onto the FPDP bus. The four
data frame types defined by the FPDP specification are listed and described below.
 Unframed data
 Single frame data
 Fixed size repeating frame data
 Dynamic size repeating frame data
UNFRAMED DATA
 Used when the source and the organization of the data is not important.
 Used when the FPDP receivers do not need to be synchronized to the data
stream.
 /SYNC is not required.
When unframed data is transmitted onto the FPDP bus, no synchronization is
required. Thus, the FPDP-TM must not generate /SYNC, and the FPDP-RM and
FPDP-R devices must not require a /SYNC pulse in order to correctly receive
data.
SINGLE FRAME DATA
 Synchronization must occur prior to data to which it applies.
 Synchronization occurs between data blocks.
 /SYNC must be asserted before /DVALID is asserted.
 Synchronization occurs infrequently, perhaps only once.
When single frame data is transmitted onto the FPDP bus, the FPDP-TM must
assert a /SYNC pulse before valid data starts being transmitted. Valid data is
transmitted when the data valid signal /DVALID is asserted. Thus, a /SYNC pulse
must be asserted before /DVALID is asserted when transmitting single frame data.
After a /SYNC pulse is asserted, the FPDP-RM and FPDP-R devices should not
accept data until the first STROBE period after /DVALID is asserted. The /SYNC
pulse does not have to be asserted again until before the start of the next data
transmission.
FIXED SIZE REPEATING FRAME DATA
 Synchronization must occur prior to data to which it applies.
 Synchronization occurs at the same time the last data word in the block before
is transferred.
 /SYNC must be asserted at the end of the data block while /DVALID is still
asserted.

Because synchronization occurs at the end of the data block, the first data
block will not be synchronized.
 Synchronization occurs frequently.
 All data frames are the same size.