Interrupts

Table 27-26. QADC Status Flags and Interrupt Sources

Queue

Queue Activity

Status

Interrupt

Flag

Enable Bit

 

 

 

 

 

 

Queue 1

Result written for last CCW in queue 1

CF1

CIE1

 

 

 

 

 

Result written for a CCW with pause bit set in queue 1

PF1

PIE1

 

 

 

 

Queue 2

Result written for last CCW in queue 2

CF2

CIE2

 

 

 

 

 

Result written for a CCW with pause bit set in queue 2

PF2

PIE2

 

 

 

 

If interrupts are enabled for an event, the QADC requests interrupt service when the event occurs. Using interrupts does not require continuously polling the status flags to see if an event has taken place; however, status flags must be cleared after an interrupt is serviced, in order to remove the interrupt request

In both polled and interrupt-driven operating modes, status flags must be re-enabled after an event occurs. Flags are re-enabled by clearing the appropriate QASR0 bits in a particular sequence. QASR0 must first be read, then 0s must be written to the flags that are to be cleared. If a new event occurs between the time that the register is read and the time that it is written, the associated flag is not cleared.

27.10.2 Interrupt Sources

The QADC includes four sources of interrupt requests, each of which is separately enabled. Each time the result is written for the last conversion command word (CCW) in a queue, the completion flag for the corresponding queue is set, and when enabled, an interrupt is requested. In the same way, each time the result is written for a CCW with the pause bit set, the queue pause flag is set, and when enabled, an interrupt is requested. Refer to Table 27-26.

The pause and complete interrupts for queue 1 and queue 2 have separate interrupt vector levels, so that each source can be separately serviced.

27-76

MCF5282 User’s Manual

MOTOROLA

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Motorola MCF5282 Qadc Status Flags and Interrupt Sources, Queue Queue Activity Status Interrupt Flag, PF1 PIE1