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Media Local Bus (MLB)
PXN20 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor
27-31
27.4.5
Channel Arbiter
The MLB Device includes a DMA Controller with a Host Bus that can access system memory. The
channel arbiter logic of the MLB Device, arbitrates requests between the different logical channel requests.
Some of the functions of the channel arbiter include:
•
determining priorities of channel requests
•
granting high priority requests based on round-robin arbitration of current high priority requests
•
granting low priority requests based on round-robin arbitration of current low priority requests, and
•
routing data and control information between channels and the Host Bus.
27.4.5.1
Round Robin Arbitration
The MLB channel arbiter uses
round-robin arbitration
to determine which logical channel is granted
access to the Host Bus. An example of the
round-robin arbitration
method is provided in
.
Figure 27-18. Round-Robin Arbitration Example
Grant 0
(g0)
Grant 1
(g1)
Grant 3
(g3)
Grant 2
(g2)
g0 r0 r1 r2 r3
g1 r0 r1 r2 r3
g2 r0 r1 r2 r3
g3 r0 r1 r2 r3
g0 r1
g1 r2
g2 r3
g3 r0
g0
r1
r2
r3
g3
r0
r1
r2
g1
r0
r2
r3
g2
r0
r1
r3
g3 r0 r1
g1 r2 r3
g
2
r0
r3
g0 r1
r2
Round-Robin Arbitration: 4 Channel Example
g
n
- Channel n grant
r
n
- Channel n request
Summary of Contents for PXN2020
Page 1: ...PXN20 Microcontroller Reference Manual Devices Supported PXN2020 PXN2120 PXN20RM Rev 1 06 2011...
Page 42: ...PXN20 Microcontroller Reference Manual Rev 1 lxiv Freescale Semiconductor...
Page 64: ...Introduction PXN20 Microcontroller Reference Manual Rev 1 1 22 Freescale Semiconductor...
Page 112: ...Signal Description PXN20 Microcontroller Reference Manual Rev 1 3 44 Freescale Semiconductor...
Page 118: ...Resets PXN20 Microcontroller Reference Manual Rev 1 4 6 Freescale Semiconductor...
Page 372: ...e200z6 Core Z6 PXN20 Microcontroller Reference Manual Rev 1 13 8 Freescale Semiconductor...
Page 412: ...e200z0 Core Z0 PXN20 Microcontroller Reference Manual Rev 1 14 14 Freescale Semiconductor...
Page 821: ...Media Local Bus MLB PXN20 Microcontroller Reference Manual Rev 1 Freescale Semiconductor 27 49...
Page 822: ...Media Local Bus MLB PXN20 Microcontroller Reference Manual Rev 1 27 50 Freescale Semiconductor...
Page 1376: ...Memory Map PXN20 Microcontroller Reference Manual Rev 1 A 118 Freescale Semiconductor...