Freescale Semiconductor MPC8260 - Manual (Page 201)

System Interface Unit (SIU)
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
Freescale Semiconductor 4-29
4.3.2.2 60x Bus Arbiter Configuration Register (PPC_ACR)
The 60x bus arbiter configuration register (PPC_ACR), shown in Figure 4-22 , defines the arbiter modes
and parked master on the 60x bus.
Table 4-10 describes PPC_ACR fields.
21 EXDD External master delay disable. Generally, the PowerQUICC II adds one clock cycle delay for each
external master access to a region controlled by the memory controller. This occurs because the
external master drives the address on the external pins (compared to internal master, like
PowerQUICC II’s DMA, which drives the address on an internal bus in the chip). Thus, it is assumed
that an additional cycle is needed for the memory controllers banks to complete the address match.
However in some cases (when the bus is operated in low frequency), this extra cycle is not needed.
The user can disable the extra cycle by setting EXDD.
0 The memory controller inserts one wait state between the assertion of TS and the assertion of CS
when external master accesses an address space controlled by the memory controller.
1 The memory controller asserts CS on the cycle following the assertion of TS by external master
accessing an address space controlled by the memory controller.
22–25 — Reserved, should be cleared.
26 — .29 µm (HiP3) devices: Reserved, should be cleared.
SPAR .25 µm (HiP4) devices: Slave parity check. If set enables parity check on 60x bus transactions to the
MPC826xA's internal memory space. In case of a parity error a core machine check is asserted and
the error is reported in TESCR1[ISBE,PAR] and TESCR2[REGS,DPR,PCI0,PCI1,LCL].
Note: TESCR2[PCI0, PCI1] are only on the MPC8250, the MPC8265, and the MPC8266.
27 ISPS Internal space port size. Defines the port size of PowerQUICC II’s internal space region as seen to
external masters. Setting ISPS enables a 32-bit master to access PowerQUICC II internal space.
0 PowerQUICC II acts as a 64-bit slave to external masters accesses to its internal space.
1 PowerQUICC II acts as a 32-bit slave to external masters accesses to its internal space.
28–31 — Reserved, should be cleared.
0 1 2 3 4 7
Field — DBGD EARB
1
PRKM
Reset 000 See note 0010
R/W R/W
Addr 0x0x10028
1
Depends on reset configuration sequence. See Section 5.4.1, “Hard Reset Configuration Word.”
Figure 4-22. PPC_ACR
Table 4-9. BCR Field Descriptions (continued)
Bits Name Description