
FlexBus
17-10
Freescale Semiconductor
17.4.1.1
General Chip-Select Operation
When a bus cycle is routed to the FlexBus, the device first compares its address with the base address and
mask configurations programmed for chip-selects 0 to 5 (configured in CSCR0 – CSCR5). The results
depend on if the address matches or not as shown in
.
17.4.1.2
8-, 16-, and 32-Bit Port Sizing
Static bus sizing is programmable through the port size bits, CSCR[PS]. The processor always drives a
-bit address on the FB_A bus regardless of the external device’s address size. The external device must
connect its address lines to the appropriate FB_A bits from FB_A0 upward. It must also connect its data
lines to the FB_D bus from FB_D31 downward. No bit ordering is required when connecting address and
data lines to the FB_A and FB_D buses. For example, a full 16-bit address/16-bit data device connects its
addr[15:0] to FB_A[16:1] and data[15:0] to FB_D[31:16]. See
17.4.1.3
Global Chip-Select Operation
FB_CS0, the global (boot) chip-select, supports external boot memory accesses before system
initialization. Its operation differs from other external chip-select outputs after system reset.
After system reset, FB_CS0 is asserted for every external access. No other chip-select can be used until
the valid bit, CSMR0[V], is set; at this point FB_CS0 functions as configured. After this, FB_CS[5:1] can
be used as well. At reset, the logic levels on the FB_D[4:3] signals determine global chip-select port size.
17.4.2
Data Transfer Operation
Data transfers between the chip and other devices involve these signals:
The address, write data, FB_TS, FB_CS
n,
and all attribute signals change on the rising edge of the FlexBus
clock (FB_CLK). Read data is latched into the device on the rising edge of the clock.
Table 17-6. Results of Address Comparison
Address Matches
CSARn?
Result
Yes,
one CSAR
The appropriate chip-select is asserted, generating an external bus cycle as defined in the chip-select
control register.
No
The internal bus cycle terminates and no chip select is asserted.
Yes,
multiple CSARs
The chip-select signals are driven. However, they are driven using an external burst-inhibited bus cycle
with external termination on a 32-bit port.
•
Address/data bus (FB_A[23:0], FB_D[31:0])
•
Control signals (FB_TS, FB_TA, FB_CS
n
, FB_OE, FB_BE/BWE[3:0])
•
Attribute signals (FB_R/W)
24
See
Chapter 9, “Chip Configuration Module (CCM),”
for more information.
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...
Страница 436: ...Fast Ethernet Controller FEC 19 44 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
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...
Страница 790: ...Message Digest Hardware Accelerator MDHA 33 20 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
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...