
NXP Semiconductors
PNX15xx/952x Series
Volume 1 of 1
Chapter 3: System On Chip Resources
PNX15XX_PNX952X_SER_N_4
NXP B.V. 2007. All rights reserved.
Product data sheet
Rev. 4.0 — 03 December 2007
3-113
the program is in a phase where it is planned to be used). This creates random
addresses that can target the APERT1 aperture. Therefore the load may generate a
transaction on the PCI bus that may have some side effects. Furthermore the
performance are deteriorated by a long CPU stall cycle that is dependent on the
completion of PCI bus transaction (the CPU does not continue unless the read has
completed). To avoid these long CPU stall cycles it is recommended to disable the
APERT1 when not used. This is achieved by setting the right mode into the TM3260
DC_LOCK_CTL M MIO register o r b y s etting TM32_APERT1_LO and
TM32_APERT1_HI to the same value.
Requests from the PCI bus or the TM3260 targeting the DRAM aperture do not
go through the DCS bus. Instead the requests are routed directly to the MMI
module. The DRAM aperture dened in the DCS bus is exclusively dened for the
boot module. When the boot module is programmed to boot PNX15xx/952x
Series from an EEPROM, the boot module fetches write commands from the
EEPROM. Each write command is sent to the DCS bus. If the write address falls
between the aperture dened by DCS_DRAM_LO and DCS_DRAM_HI,
Section 2.4.1, then the write data is transferred to the MMI module. This gate
allows transfer to the main memory, a binary program, (that is stored into the
EEPROM) for the TM3260. The bus connecting the module to the MMI is
2.4 The Programmable DCS Apertures
The address range dened by the content of DCS_DRAM_LO or DCS_DRAM_HI
must not overlap the address ranges of the other apertures on the DCS bus. This can
happen temporarily when changing either the DCS_DRAM_LO or the
DCS_DRAM_HI. Therefore any change of the DCS_DRAM_LO or DCS_DRAM_HI
registers must be done by rst disabling the DCS DRAM aperture. This is achieved by
starting to change DCS_DRAM_LO or DCS_DRAM_HI such that DCS_DRAM_LO is
greater than DCS_DRAM_HI.
Similar constraints apply respectively to PCI_BASE1_LO and PCI_BASE1_HI, and
PCI_BASE2_LO and PCI_BASE2_HI.