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NXP Semiconductors
PNX15xx/952x Series
Volume 1 of 1
Chapter 30: DCS Network
PNX15XX_PNX952X_SER_N_4
NXP B.V. 2007. All rights reserved.
Product data sheet
Rev. 4.0 — 03 December 2007
30-819
that most recently performed a transaction. The initiator with a default grant can
access a target one clock cycle faster than an initiator without the default grant.
Assigning the default grant to the initiator that most recently used the “bus” is
expected to yield the highest performance, since one initiator is likely to execute
several transactions at once.
To achieve the round robin feature with a dynamic default grant, the arbiter uses an
internal priority comparator. The comparator selects an initiator to grant by comparing
the “priorities” of each device. The priority value consists of three bits. The most
signicant bit is high when there is a pending request from that initiator. The second
most signicant bit is generated by “l(fā)ast_grant”, which will be high for the most
recently granted initiator
only if that initiator does not have a pending request, and low
for all other initiators. The third bit is a “uniform scheduling” value. This will be set to
one for all bit locations higher than the last granted initiator and zero for all lower
ones. The priority block will pick the highest value (3-bit) input. In the case of a tie, the
lower numbered port will win.
2.4 Endian Mode
All DCS network ports use 32-bit data paths and the data values are viewed as 32-bit
quantities. Even when an 8 or 16-bit read or write is performed, the transfer is
considered to be a portion of a larger 32-bit quantity. The data transfers are never
viewed as packed 8 or 16-bit values.
3.
Register Descriptions
3.1 Register Summary
Table 1 summarizes the control and status registers visible inside the DCS Controller.
Remark: The BC_INT_EN register is R/W, however newly written software drivers
should consider BC_INT_EN as read only and should use the BC_INT_CLR_ENABLE
and BC_INT_SET_ENABLE registers to update the value of BC_INT_EN.
Table 1:
DCS Controller_TriMedia Conguration Register Summary
Offset
Symbol
Description
0x10 3000
BC_CTRL
Timeout control register
0x10 300C
BC_ADDR
Error and timeout address register
0x10 3010
BC_STAT
Error and timeout status register
0x10 30D8
BC_INT_CLR_ENABLE
Clear bits in BC_INT_EN
0x10 30DC
BC_INT_SET_ENABLE
Set bits in BC_INT_EN
0x10 3FE0
BC_INT_STATUS
Interrupt Status register
0x10 3FE4
BC_INT_EN
Interrupt Enable register
0x10 3FE8
BC_INT_CLR
Interrupt Clear register
0x10 3FEC
BC_INT_SET
Interrupt software set register
0x10 3FFC
BC_MOD_ID
Module identication and revision information