![Freescale Semiconductor KKL02Z32CAF4R Скачать руководство пользователя страница 260](http://html1.mh-extra.com/html/freescale-semiconductor/kkl02z32caf4r/kkl02z32caf4r_reference-manual_2330635260.webp)
Table 19-1. How AXBS grants control of a slave port to a master (continued)
When
Then AXBS grants control to the requesting master
• The current master is not running a transfer.
• The new requesting master's priority level is higher than
that of the current master.
The requesting master's priority level is lower than the current
master.
At the conclusion of one of the following cycles:
• An IDLE cycle
• A non-IDLE cycle to a location other than the current
slave port
19.3.2.3 Round-robin priority operation
When operating in round-robin mode, each master is assigned a relative priority based on
the master port number. This relative priority is compared to the master port number (ID)
of the last master to perform a transfer on the slave bus. The highest priority requesting
master becomes owner of the slave bus at the next transfer boundary. Priority is based on
how far ahead the ID of the requesting master is to the ID of the last master.
After granted access to a slave port, a master may perform as many transfers as desired to
that port until another master makes a request to the same slave port. The next master in
line is granted access to the slave port at the next transfer boundary, or possibly on the
next clock cycle if the current master has no pending access request.
As an example of arbitration in round-robin mode, assume the crossbar is implemented
with master ports 0, 1, 4, and 5. If the last master of the slave port was master 1, and
master 0, 4, and 5 make simultaneous requests, they are serviced in the order: 4 then 5
then 0.
The round-robin arbitration mode generally provides a more fair allocation of the
available slave-port bandwidth (compared to fixed priority) as the fixed master priority
does not affect the master selection.
19.4 Initialization/application information
No initialization is required for the crossbar switch. See the AXBS section of the
configuration chapter for the reset state of the arbitration scheme.
Initialization/application information
KL02 Sub-Family Reference Manual, Rev. 2.1, July 2013
260
Freescale Semiconductor, Inc.
Содержание KKL02Z32CAF4R
Страница 2: ...KL02 Sub Family Reference Manual Rev 2 1 July 2013 2 Freescale Semiconductor Inc...
Страница 24: ...KL02 Sub Family Reference Manual Rev 2 1 July 2013 24 Freescale Semiconductor Inc...
Страница 36: ...Orderable part numbers KL02 Sub Family Reference Manual Rev 2 1 July 2013 36 Freescale Semiconductor Inc...
Страница 76: ...Human machine interfaces HMI KL02 Sub Family Reference Manual Rev 2 1 July 2013 76 Freescale Semiconductor Inc...
Страница 94: ...Module clocks KL02 Sub Family Reference Manual Rev 2 1 July 2013 94 Freescale Semiconductor Inc...
Страница 142: ...Functional description KL02 Sub Family Reference Manual Rev 2 1 July 2013 142 Freescale Semiconductor Inc...
Страница 188: ...Memory map and register descriptions KL02 Sub Family Reference Manual Rev 2 1 July 2013 188 Freescale Semiconductor Inc...
Страница 214: ...Application information KL02 Sub Family Reference Manual Rev 2 1 July 2013 214 Freescale Semiconductor Inc...
Страница 222: ...Memory map register descriptions KL02 Sub Family Reference Manual Rev 2 1 July 2013 222 Freescale Semiconductor Inc...
Страница 256: ...Memory map and register definition KL02 Sub Family Reference Manual Rev 2 1 July 2013 256 Freescale Semiconductor Inc...
Страница 300: ...Functional description KL02 Sub Family Reference Manual Rev 2 1 July 2013 300 Freescale Semiconductor Inc...
Страница 532: ...Functional description KL02 Sub Family Reference Manual Rev 2 1 July 2013 532 Freescale Semiconductor Inc...
Страница 534: ...KL02 Sub Family Reference Manual Rev 2 1 July 2013 534 Freescale Semiconductor Inc...