External Bus Interface
MPC561/MPC563 Reference Manual, Rev. 1.2
Freescale Semiconductor
9-9
9.5.2
Single Beat Transfer
During the data transfer phase, the data is transferred from master to slave (in write cycles) or from slave
to master (on read cycles).
During a write cycle, the master drives the data as soon as it can, but never earlier than the cycle following
the address transfer phase. The master has to take into consideration the “one dead clock cycle” switching
between drivers to avoid electrical contentions. The master can stop driving the data bus as soon as it
samples the TA line asserted on the rising edge of the CLKOUT.
During a read cycle, the master accepts the data bus contents as valid at the rising edge of the CLKOUT
in which the TA signal is sampled/asserted.
9.5.2.1
Single Beat Read Flow
The basic read cycle begins with bus arbitration, followed by the address transfer, then the data transfer.
The handshakes illustrated in the following flow and timing figures (
, and
) are applicable to the fixed transaction protocol.
Figure 9-4. Basic Flow Diagram of a Single Beat Read Cycle
3. Assert bus busy (
BB
) if no other master is driving bus
4. Assert transfer start (
TS
)
5. Drive address and attributes
1. Receive address
2. Return data
3. Assert transfer acknowledge (
TA
)
Slave
Master
2. Receive bus grant (
BG
) from arbiter
1. Request bus (
BR
)
Summary of Contents for MPC561
Page 84: ...MPC561 MPC563 Reference Manual Rev 1 2 lxxxiv Freescale Semiconductor...
Page 144: ...Signal Descriptions MPC561 MPC563 Reference Manual Rev 1 2 2 46 Freescale Semiconductor...
Page 206: ...Central Processing Unit MPC561 MPC563 Reference Manual Rev 1 2 3 62 Freescale Semiconductor...
Page 302: ...Reset MPC561 MPC563 Reference Manual Rev 1 2 7 14 Freescale Semiconductor...
Page 854: ...Time Processor Unit 3 MPC561 MPC563 Reference Manual Rev 1 2 19 24 Freescale Semiconductor...
Page 968: ...Development Support MPC561 MPC563 Reference Manual Rev 1 2 23 54 Freescale Semiconductor...
Page 1144: ...Internal Memory Map MPC561 MPC563 Reference Manual Rev 1 2 B 34 Freescale Semiconductor...
Page 1212: ...TPU3 ROM Functions MPC561 MPC563 Reference Manual Rev 1 2 D 60 Freescale Semiconductor...
Page 1216: ...Memory Access Timing MPC561 MPC563 Reference Manual Rev 1 2 E 4 Freescale Semiconductor...