PNX17XX Datasheet, PDF (475/832 Pages) NXP Semiconductors – Connected Media Processor

Philips Semiconductors
Volume 1 of 1
PNX17xx Series
Chapter 13: FGPO: Fast General Purpose Output
2.9 Timestamp
If enabled, by setting FGPO_CTL.TSTAMP_SELECT bit to ‘1’, an 8-byte header is
read from memory before the data. The first 32-bit word contains the start time
(timestamp) of the record or message. The second 32-bit word may contain the
length of the record or message if the VAR_LENGTH bit is set, else the contents are
ignored.
The timestamp clock is derived from the main timestamp clock which runs at 13.5
MHz when the GPIO module module is clocked by the 108 MHz clock.
Remark: The length of the header is NOT INCLUDED in the FGPO_REC_SIZE value
but MUST be included in the FGPO_STRIDE value.
If both FGPO_CTL.TSTAMP_SELECT and FGPO_CTL.VAR_LENGTH bits are set,
then the timestamp word is read from memory before the length word.
Enabling timestamp mode overrides all other buffer and record synchronization.
2.10 Variable Length
If enabled, by setting FGPO_CTL.VAR_LENGTH bit to ‘1’, an 8-byte header is read
from memory before the data. The first 32-bit word may contain the start time
(timestamp) of the record or message if TSTAMP_SELECT is set, else the contents
are ignored. The second 32-bit word contains the length of the record or message.
Remark: The length of the header is NOT INCLUDED in the FGPO_REC_SIZE value
but MUST be included in the FGPO_STRIDE value.
If both FGPO_CTL.TSTAMP_SELECT and FGPO_CTL.VAR_LENGTH bits are set,
then the timestamp word is read from memory before the length word.
In message mode, if the message length read from the header is greater than the
value programmed into the FGPO_REC_SIZE register then the message will be
truncated to the length contained in the FGPO_REC_SIZE register.
2.11 Output Time Registers
To help determine the actual time when a transfer took place there are the
FGPO_TIME1 and FGPO_TIME2 registers. These registers hold the time when the
last sample from a buffer is sent out. This serves to observe the actual departure time
in non-timestamp operation modes.
2.12 Double Buffer Operation
Figure 4 shows the major states associated with double buffering. In the following
discussion a buffer start event means either the current buffer is done or that an
external buffer sync event tells the FGPO to terminate the current buffer and switch to
the next buffer. The exact semantics depends on the operating mode of the FGPO.
Upon reset (hardware or software), all status and control bits are placed in the reset
condition and no buffer is active. Once software has programmed the required
parameters, it is safe to enable output by setting OUTPUT_ENABLE_1 and
PNX17XX_SER_1
Preliminary data sheet
Rev. 1 — 17 March 2006
© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
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