Motorola MCF5281, MCF5282 user manual CCW Priority Situation

Models: MCF5282 MCF5281

1 816
Download 816 pages 28.97 Kb
Page 627
Image 627

Digital Control Subsystem

Q1:

Q2:

QS:

T1

Q1: C1 C2 C3 C4

 

 

 

 

T2

 

CF1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Q2:

 

 

 

 

 

 

C1

 

C2

 

C3

C4

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CF2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

IDLE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

IDLE

 

 

 

ACTIVE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

IDLE

 

 

 

TRIGGERED

 

 

 

ACTIVE

 

 

 

IDLE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0000

1000

 

 

 

 

1011

 

 

 

0010

 

 

0000

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 27-26. CCW Priority Situation 4

Situation S5 (Figure 27-27)shows that when multiple queue 2 trigger events are detected while queue 1 is busy, the trigger overrun error bit is set, but queue 1 execution is not disturbed. Situation S5 also shows that the effect of queue 2 trigger events during queue 1 execution is the same when the pause feature is used for either queue.

Q1:

Q2:

QS:

 

T1

 

 

 

T1

 

 

 

 

Q1:

C1

C2

 

 

 

C3

C4

 

 

 

 

T2 T2 PF1

 

 

 

 

T2 T2 CF1

 

 

 

Q2:

 

C1

C2

 

 

 

C3

C4

 

 

 

TOR2

 

PF2

 

TOR2

 

 

CF2

IDLE

ACTIVE

 

PAUSE

 

ACTIVE

 

 

IDLE

IDLE

 

TRIG

ACTIVE

PAUSE

TRIG

ACTIVE

IDLE

0000

1000

1011

0110

0101

1001

1011

0010

0000

Figure 27-27. CCW Priority Situation 5

The remaining situations, S6 through S11, show the impact of a queue 1 trigger event occurring during queue 2 execution. Because queue 1 has higher priority, the conversion taking place in queue 2 is aborted so that there is no variable latency time in responding to queue 1 trigger events.

In situation 6 (Figure 27-28), the conversion initiated by the second CCW in queue 2 is aborted just before the conversion is complete, so that queue 1 execution can begin. Queue 2 is considered suspended. After queue 1 is finished, queue 2 starts over with the first CCW,

MOTOROLA

Chapter 27. Queued Analog-to-Digital Converter (QADC)

27-43

Page 627
Image 627
Motorola MCF5281, MCF5282 user manual CCW Priority Situation