PTD
EMPL
CSTC
EMS
PMT
...
...
...
... ...
1
0
1
1
1
2
415
61
7
8191101111213114115
19
1
20
31
1
t t
t t t
EBTC
RTC
EM
PH
BPF
PME
Figure 16-15. EBC Configuration Register (EBCO_CFG)
0
EBTC
External Bus Three-State Control
Default after reset is EBTC=1 . See "Effect of
o Address, data and control signals are Driver Enable Programming on EBC Signal
high-Z between EBC transfers.
States" on page 16-5.
1 Between EBC transfers the peripheral data
bus, address bus and control signals are
driven.
1 PTD
Device-Paced Time-out Disable
If
PTD=1, the EBC waits indefinitely for
o Enabled time-outs
assertion of PerReady during device-paced
1 Disable time-outs
accesses.
2:4 RTC
Ready Timeout Count
When
PTD=O,
the number of cycles from
000 16 PerClk cycles
PerAddrO:31 changing until a time-out error
001
32 PerClk cycles occurs.
010 64 PerClk cycles
011
128 PerClk cycles
100 256 PerClk cycles
101
512 PerClk cycles
110 1024 PerClk cycles
111
2048 PerClk cycles
5:6 EMPL External Master Priority Low
The PLB priority for external master initiated
00 Low
transfers when the external master hold
01
Medium low
priority input is low (HoldPri=O).
10 Medium high
11
High
7:8 EM
PH
External Master Priority High The PLB priority for external master initiated
00 Low
transfers when the external master hold
01
Medium low
priority input is high (HoldPri=1).
10 Medium high
11
High
9
CSTC Chip Select Three-state Control
Default after reset is CSTC=1. See "Effect of
o PerCSO:7 are high-Z between EBC Driver Enable Programming on EBC Signal
transfers and when an external master is
States" on page 16-5.
active (HoldAck=1)
1
PerCSO:7 are always driven.
10:11 BPF
Burst Prefetch
Controls the amount of data prefetching
00 Prefetch 1 doubleword when the EBC is servicing a PLB burst read.
01
Prefetch 2 doublewords
For most applications set this field to
ObOO.
10 Prefetch 4 doublewords
11
Reserved
16-24 PPC405GP User's Manual
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