PXS20RM Datasheet, PDF (317/1368 Pages) Freescale Semiconductor, Inc – PXS20 Microcontroller

Crossbar Switch (XBAR)
1
2
3
4
5
6
7
8
9
hclk
m0 request
m2 request
m4 request
Park
Highest
Priority
Requester
Address/Cntrl
owner
htrans
Master 2
Master 0 None Master 2 None Master 4 None Master 2
None
XBAR Master 0 Master 2 XBAR XBAR Master 4
Master 2
XBAR
IDLE
NSEQ NSEQ
IDLE
IDLE
NSEQ
NSEQ
IDLE
hready
Figure 15-8. Parking on a specific master
Figure 15-9 illustrates parking on the last master. Note that in cycle 6 simultaneous requests are made by
master 2 and master 4. Although master 2 has higher priority, the slave bus is parked on master 4 so master
4’s access will be taken first. The slave port parks on master 2 once it has given control to master 2. This
same situation can occur when parking on a specific master as well.
1
2
3
4
5
6
7
8
9
hclk
m0 request
m2 request
m4 request
Park
Highest
Priority
Requester
Address/Cntrl
owner
Last Master
Master 0
Master 0 None Master 4
XBAR Master 0 XBAR
Master 4
None
Master 4 XBAR
Master 2
Master 4
Master 2
None
Master 2
XBAR
htrans
IDLE
NSEQ
IDLE
NSEQ
IDLE
NSEQ
NSEQ
IDLE
hready
Figure 15-9. Parking on last master
Freescale Semiconductor
PXS20 Microcontroller Reference Manual, Rev. 1
15-23