5962F9211804VXA View Datasheet(PDF) - Aeroflex UTMC
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5962F9211804VXA Datasheet PDF : 177 Pages
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2.2.5 Data Pointer A and B
Data Pointer A and B contain address information for the retrieval and storage of message data words. In the index mode of operation,
the SRT reads Data Pointer A to determine the location of data for retrieval or storage. The SRT uses the Data Pointer to initialize
an internal counter; the counter increments after each data word. For a receive command, the SRT stores the incoming data word
sequentially into memory. As part of command post-processing, the SRT writes a new data pointer into the descriptor block. The
SRT continues to update the data pointer until the Control Word index field decrements to zero. An example is shown in figure 5.
Note: The index feature is not applicable for transmit commands (i.e., T/R bit = 1).
For ping-pong buffer operation, the host uses either Data Pointer A or Data Pointer B. The SRT determines which pointer to access
via the state of Control Word bit 2. The SRT retrieves or stores data words from the address contained in the data pointer, automatically
incrementing the data pointer as data words are received. The data pointer is never updated as part of command post-processing in
the ping-pong mode of operation. See figures 6 and 7.
Bit
Number
Mnemonic
Description
15-0
DP(15:0)
Data Pointer Bits. The second and third words of the descriptor block contain the data
buffer location. The SRT accesses either Data Pointer A or Data Pointer B depending on
the state of Control Word Bit 2 during ping-pong operation. For index operation, the SRT
accesses only Data Pointer A. The SRT updates Data Pointer A after message processing
is complete and the index field is not equal to zero and ping-pong operation disabled. Bit
15 is the most significant bit; bit 0 is the least significant bit.
2.2.6 Broadcast Data Pointer
The following bits describe the receive subaddress/mode code descriptor Broadcast Data Pointer. This word contains the address
for the Message Information word, Time-Tag word, and data words associated with a broadcast command. The SRT automatically
increments this data pointer during command post-processing, if ping-pong operation disabled.
Bit
Number
Mnemonic
Description
15-0
BP(15:0)
Broadcast Data Pointer. The fourth word of the descriptor block contains the broadcast
data buffer location. This pointer can reside anywhere inside of a 64K data space. The
SRT accesses this pointer when Control Word bit 0 is a logic one and broadcast is enabled.
Bit 15 is the most significant bit; bit 0 is the least significant bit.
Note: If ping-pong is enabled, this pointer does not update.
Note: When the broadcast command is followed by a Transmit Last Command or Transmit
Status Word mode code, the SRT transmits a status word with bit 15 of the status word
set to a logic one. The broadcast bit is cleared by reception of the next valid non-broadcast
command.
2.3 Data Structures
The following sections discuss the data structures that result
from command processing. For each complete message
processed, the SRT generates a Message Information word and
Time-Tag word. These words aid the host or subsystem
in further message processing. The Message Information word
contains word count, message type, and message error
information. The Time-Tag word is a 16-bit word containing the
command validity time. The Time-Tag word data comes from
the SRT’s internal Time-Tag counter.
See section 5, Enhanced Family SµMMIT Operation for
additional data structure information
SµMMIT FAMILY
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