MSC8113 Reference Manual, Rev. 0
13-34
Freescale Semiconductor
System Bus
The system must ensure that the first (or only) assertion of
TA
does not occur sooner than the
cycle of the first assertion of
ARTRY
on the bus, or conversely, that
ARTRY
is never asserted later
than the cycle of the first or only assertion of
TA.
This guarantees the relationship between
TA
and
ARTRY
such that, in case of an address retry, the data can be cancelled in the device before it can
be forwarded to the internal storage locations. Generally, the memory system must also detect
this event and abort any transfer in progress. If this
TA/ARTRY
relationship is not met, the device
master may enter an undefined state. You can use PPC_ACR[DBGD] to ensure correct operation
of the system.
During the clock of a qualified
ARTRY
, each device master determines whether it should deassert
BR
and ignore
BG
on the following cycle. The following cycle is the window-of-opportunity for
the snooping master. During this window, only the snooping master that asserted
ARTRY
and
requires a snoop copyback operation is allowed to assert
BR
. This guarantees the snooping master
a window of opportunity to request and be granted the bus before the just-retried master can
restart its transaction.
BG
is also blocked in the window-of-opportunity, so the arbiter has a
chance to deassert
BG
to an already granted potential bus master to perform a new arbitration.
13.2.3.11 Address Tenure Timing Configuration
During address tenures initiated by 60x-compatible bus devices, the timing of the MSC8113
assertion of
AACK
is determined by the BCR[APD] bit and the pipeline status of the system bus.
Because the MSC8113 device can support one level of pipelining, it uses
AACK
to control the
system bus pipeline condition. To maintain the one-level pipeline,
AACK
is not asserted for a
pipelined address tenure until the current data tenure ends. The MSC8113 device also delays
asserting
AACK
until no more address retry conditions can occur. The earliest the MSC8113 can
assert
AACK
is the clock cycle when the wait-state values set by BCR[APD] have expired.
BCR[APD] specifies the minimum number of address tenure wait states for address operations
initiated by 60x-compatible bus devices. BCR[APD] indicates how many cycles the MSC8113
should wait for
ARTRY
, but because it is assumed that
ARTRY
can be asserted (by other masters)
only on cacheable address spaces, BCR[APD] is considered only on transactions that hit a
60x-assigned memory controller bank and have
GBL
asserted during the address phase.
Extra wait states may occur because of other MSC8113 configuration parameters. In systems
with multiple potential masters, the number of wait states configured by BCR[APD] should be at
least as large as the value the slowest master would need to assert a snoop response. For example,
additional wait states are required when the internal processor is running in 1:1 clock mode; this
case requires at least one wait state to generate the
ARTRY
response.
Содержание MSC8113
Страница 1: ...MSC8113 Reference Manual Tri Core 16 Bit Digital Signal Processor MSC8113RM Rev 0 May 2008 ...
Страница 20: ...MSC8113 Reference Manual Rev 0 xx Freescale Semiconductor Contents ...
Страница 28: ...MSC8113 Reference Manual Rev 0 xxviii Freescale Semiconductor ...
Страница 56: ...MSC8113 Reference Manual Rev 0 1 28 Freescale Semiconductor MSC8113 Overview ...
Страница 76: ...MSC8113 Reference Manual Rev 0 2 20 Freescale Semiconductor SC140 Core Overview ...
Страница 134: ...MSC8113 Reference Manual Rev 0 4 30 Freescale Semiconductor System Interface Unit SIU ...
Страница 168: ...MSC8113 Reference Manual Rev 0 6 18 Freescale Semiconductor Boot Program ...
Страница 180: ...MSC8113 Reference Manual Rev 0 7 12 Freescale Semiconductor Clocks ...
Страница 260: ...MSC8113 Reference Manual Rev 0 8 80 Freescale Semiconductor Memory Map ...
Страница 300: ...MSC8113 Reference Manual Rev 0 9 40 Freescale Semiconductor Extended Core ...
Страница 304: ...MSC8113 Reference Manual Rev 0 10 4 Freescale Semiconductor MQBus and M2 Memory ...
Страница 308: ...MSC8113 Reference Manual Rev 0 11 4 Freescale Semiconductor SQBus ...
Страница 544: ...MSC8113 Reference Manual Rev 0 16 46 Freescale Semiconductor Direct Memory Access DMA Controller ...
Страница 590: ...MSC8113 Reference Manual Rev 0 17 46 Freescale Semiconductor Interrupt Processing ...
Страница 614: ...MSC8113 Reference Manual Rev 0 18 24 Freescale Semiconductor Debugging ...
Страница 622: ...MSC8113 Reference Manual Rev 0 19 8 Freescale Semiconductor Internal Peripheral Bus IPBus ...
Страница 724: ...MSC8113 Reference Manual Rev 0 21 32 Freescale Semiconductor UART ...
Страница 920: ...MSC8113 Reference Manual Rev 0 25 150 Freescale Semiconductor Ethernet Controller ...
Страница 1171: ...MSC8113 Reference Manual Rev 0 Freescale Semiconductor C 61 EF wait_rts P 01077FFC 9F rts 71 ...
Страница 1172: ...MSC8113 Reference Manual Rev 0 C 62 Freescale Semiconductor MSC8113 Boot Code ...
Страница 1202: ...MSC8113 Reference Manual Rev 0 Index 30 Freescale Semiconductor Index ...