
FlexBus
Freescale Semiconductor
17-13
17.4.5
FlexBus Timing Examples
NOTE
Because this device shares the FlexBus signals with the SDRAM controller,
all signals, except the chip selects, tristate between bus cycles.
17.4.5.1
Basic Read Bus Cycle
During a read cycle, the ColdFire device receives data from memory or a peripheral device.
is a read cycle flowchart.
S1
All
FB_TS is negated on the rising edge of FB_CLK, and FB_CSn is asserted. Data is driven on
FB_D[31:X] for writes, and FB_D[31:X] is tristated for reads. Address continues to be driven on
the FB_A pins.
If FB_TA is recognized asserted, then the cycle moves on to S2. If FB_TA is not asserted
internally or externally, then the S1 state continues to repeat.
Read
Data is driven by the external device before the next rising edge of FB_CLK (the rising edge that
begins S2) with FB_TA asserted.
S2
All
For internal termination, FB_CSn is negated and the internal system bus transfer is completed.
For external termination, the external device should negate FB_TA, and the FB_CSn chip select
negates after the rising edge of FB_CLK at the end of S2.
Read
The processor latches data on the rising clock edge entering S2. The external device can stop
driving data after this edge. However, data can be driven until the end of S3 or any additional
address hold cycles.
S3
All
Address, data, and FB_R/W go invalid off the rising edge of FB_CLK at the beginning of S3,
terminating the read or write cycle.
Table 17-7. Bus Cycle States (continued)
State
Cycle
Description
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...