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Freescale Semiconductor
17-1
Chapter 17
FlexBus
17.1
Introduction
This chapter describes external bus data transfer operations and error conditions. It describes transfers
initiated by the ColdFire processor (or any other bus master) and includes detailed timing diagrams
showing the interaction of signals in supported bus operations.
NOTE
In this chapter, unless otherwise noted, clock refers to the FB_CLK used for
the external bus (f
sys/3
).
The external data bus is shared between the FlexBus module and the
SDRAM controller. When the SDRAM controller is in SDR mode
(DRAMSEL = 1), the data bus is switched dynamically between the
SDRAM controller and the FlexBus module. However, when the SDRAM
controller is in DDR mode (DRAMSEL = 0), D[31:16] is dedicated to the
SDRAM data bus and D[15:0] is dedicated to the FlexBus data bus. In this
case, external pins D[15:0], are mapped internally to the upper two bytes of
the FlexBus data bus, FB_D[31:16]. This chapter only uses FB_D[31:0] or
FB_D[31:
X
] to designate the data bus, but the actual pins used depend on
the DRAMSEL setting. Take this into consideration throughout this chapter.
17.1.1
Overview
A multi-function external bus interface called the FlexBus interface controller is provided on the device
with basic functionality of interfacing to slave-only devices with a maximum bus frequency up to 80 MHz.
It can be directly connected to the following asynchronous or synchronous devices with little or no
additional circuitry:
•
External boot ROMs
•
Flash memories
•
Gate-array logic
•
Other simple target (slave) devices
For asynchronous devices, a simple chip-select based interface can be used.
The FlexBus interface has up to six general purpose chip-selects, FB_CS[5:0]. The actual number of chip
selects available depends upon the device and its pin configuration. See
Chip-select FB_CS0 can be dedicated to boot memory access and programmed to be byte (8 bits), word
MCF5329 Reference Manual, Rev 3
Summary of Contents for MCF5329
Page 106: ...ColdFire Core 3 32 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 148: ...Cache 5 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 154: ...Static RAM SRAM 6 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 184: ...Power Management 8 18 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 204: ...Reset Controller Module 10 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 220: ...System Control Module SCM 11 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 228: ...Crossbar Switch XBS 12 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 268: ...General Purpose I O Module 13 40 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 392: ...SDRAM Controller SDRAMC 18 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 436: ...Fast Ethernet Controller FEC 19 44 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 594: ...FlexCAN 23 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 678: ...Pulse Width Modulation PWM Module 26 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 684: ...Watchdog Timer Module 27 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 704: ...DMA Timers DTIM0 DTIM3 29 12 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 754: ...UART Modules 31 34 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 770: ...I2 C Interface 32 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 866: ...Debug Module 36 50 Freescale Semiconductor MCF5329 Reference Manual Rev 3...