Motorola MCF5281, MCF5282 user manual Mpark Field Description

Models: MCF5282 MCF5281

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Internal Bus Arbitration

 

 

 

Table 8-7. MPARK Field Description

 

 

 

 

Bits

Name

 

Description

 

 

 

31–26

Reserved, should be cleared.

 

 

 

25

M2_P_EN

DMA bandwith control enable

 

 

0 disable the use of the DMA's bandwidth control to elevate the priority of its bus requests.

 

 

1 enable the use of the DMA's bandwidth control to elevate the priority of its bus requests.

 

 

 

24

BCR24BIT

Enables the use of 24 bit byte count registers in the DMA module

 

 

0 DMA BCRs function as 16 bit counters.

 

 

1 DMA BCRs function as 24 bit counters.

 

 

 

23–22

M3_PRTY

Master priority level for master 3 (Fast Ethernet Controller)

 

 

00

fourth (lowest) priority

 

 

01

third priority

 

 

10

second priority

 

 

11

first (highest) priority

 

 

 

21–20

M2_PRTY

Master priority level for master 2 (DMA Controller)

 

 

00

fourth (lowest) priority

 

 

01

third priority

 

 

10

second priority

 

 

11

first (highest) priority

 

 

 

19–18

M0_PRTY

Master priority level for master 0 (ColdFire Core)

 

 

00

fourth (lowest) priority

 

 

01

third priority

 

 

10

second priority

 

 

11

first (highest) priority

 

 

 

17–16

M1_PRTY

Master priority level for master 1 (Not used in user mode)

 

 

00

fourth (lowest) priority

 

 

01

third priority

 

 

10

second priority

 

 

11

first (highest) priority

 

 

 

15

Reserved, should be cleared.

 

 

 

14

FIXED

Fixed or round robin arbitration

 

 

0

round robin arbitration

 

 

1

fixed arbitration

 

 

 

13

TIMEOUT

Timeout Enable

 

 

0 disable count for when a master is locked out by other masters.

 

 

1

enable count for when a master is locked out by other masters and allow access when

 

 

 

LCKOUT_TIME is reached.

 

 

 

12

PRKLAST

Park on the last active master or highest priority master if no masters are active

 

 

0 park on last active master

 

 

1 park on highest priority master

 

 

 

11–8

LCKOUT_TIME

Lock-out Time. Lock-out time for a master being denied the bus.

 

 

The lock out time is defined as 2^ LCKOUT_TIME[3:0].

 

 

 

7–0

Reserved, should be cleared.

 

 

 

 

The initial state of the master priorities is M3 > M2 > M1 > M0. System software should guarantee that the programmed Mn_PRTY fields are unique, otherwise the hardware defaults to the initial-state priorities.

MOTOROLA

Chapter 8. System Control Module (SCM)

8-13

Page 199
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Motorola MCF5281, MCF5282 user manual Mpark Field Description