
Crossbar Switch (XBS)
Freescale Semiconductor
12-3
12.2
Features
The crossbar switch includes these distinctive features:
•
Symmetric crossbar bus switch implementation
— Allows concurrent accesses from different masters to different slaves
— Slave arbitration attributes configured on a slave by slave basis
•
32 bits wide and supports byte, word (2 byte), longword (4 byte), and 16 byte burst transfers
•
Operates at a 1-to-1 clock frequency with the bus masters
12.3
Modes of Operation
The crossbar switch supports two arbitration modes (fixed or round-robin), which may be set on a slave
by slave basis. Slaves configured for fixed arbitration mode have a unique arbitration level assigned to
each bus master.
In fixed priority mode, the highest priority active master accessing a particular slave is granted the master
bus path to that slave. A higher priority master blocks access to a given slave from a lower priority master
if the higher priority master continuously requests that slave. See
Section 12.5.1.1, “Fixed-Priority
In round-robin arbitration, active masters accessing a particular slave are initially granted the slave based
on their master port number. Master priority is then modified in a wrap-around manner to give all masters
fair access to the slave. See
Section 12.5.1.2, “Round-Robin Priority Operation.”
12.4
Memory Map / Register Definition
Two registers reside in each slave port of the crossbar switch. Read- and write-transfers require two bus
clock cycles. The registers can only be read from and written to in supervisor mode. Additionally, these
registers can only be read from or written to by 32-bit accesses.
A bus error response is returned if an unimplemented location is accessed within the crossbar switch. See
Section 11.2.7, “SCM Interrupt Status Register (SCMISR).”
The slave registers also feature a bit that, when set, prevents the registers from being written. The registers
remain readable, but future write attempts have no effect on the registers and are terminated with a bus
error response to the master initiating the write. The core, for example, takes a bus error interrupt.
shows the memory map for the crossbar switch program-visible registers.
Table 12-2. XBS Memory Map
Address
Register
Width
(bits)
Access
Reset Value
Section/Page
0xFC00_4100
Priority Register Slave 1 (XBS_PRS1)
32
R/W
0x6543_0210
0xFC00_4110
Control Register Slave 1 (XBS_CRS1)
32
R/W
0x0000_0000
0xFC00_4400
Priority Register Slave 4 (XBS_PRS4)
32
R/W
0x6543_0210
0xFC00_4410
Control Register Slave 4 (XBS_CRS4)
32
R/W
0x0000_0000
MCF5329 Reference Manual, Rev 3
Содержание MCF5329
Страница 106: ...ColdFire Core 3 32 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 126: ...Enhanced Multiply Accumulate Unit EMAC 4 20 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 148: ...Cache 5 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 154: ...Static RAM SRAM 6 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 184: ...Power Management 8 18 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 204: ...Reset Controller Module 10 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 220: ...System Control Module SCM 11 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 228: ...Crossbar Switch XBS 12 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 268: ...General Purpose I O Module 13 40 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 392: ...SDRAM Controller SDRAMC 18 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
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Страница 564: ...Liquid Crystal Display Controller LCDC 22 44 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 594: ...FlexCAN 23 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 678: ...Pulse Width Modulation PWM Module 26 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 684: ...Watchdog Timer Module 27 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 692: ...Programmable Interrupt Timers PIT0 PIT3 28 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 704: ...DMA Timers DTIM0 DTIM3 29 12 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 720: ...Queued Serial Peripheral Interface QSPI 30 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 754: ...UART Modules 31 34 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 770: ...I2 C Interface 32 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
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Страница 866: ...Debug Module 36 50 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 902: ...Register Memory Map Quick Reference A 26 Freescale Semiconductor MCF5329 Reference Manual Rev 3...