MPC5553/MPC5554 Microcontroller Reference Manual, Rev. 5
Freescale Semiconductor 19-71
19.4.3.6 CFIFO and Trigger Status
19.4.3.6.1 CFIFO Operation Status
Each CFIFO has its own CFIFO status field. CFIFO status (CFS) can be read from EQADC_CFSSR (see
Section 19.3.2.11, “eQADC CFIFO Status Register (EQADC_CFSR).” Figure 19-39 and Table 19-45
indicate the CFIFO status switching condition. Refer to Table 19-18 for the meaning of each CFIFO
operation status. The last CFIFO to transfer a command to an on-chip ADC can be read from the LCFTn
(n=0,1) fields (see Section 19.3.2.10, “eQADC CFIFO Status Snapshot Registers 0–2
(EQADC_CFSSRn).” The last CFIFO to transfer a command to a specific external command buffer can
be identified by reading the EQADC_CFSSRn[LCFTSSI] and EQADC_CFSSRn[ENI] fields (see
Section 19.3.2.10, “eQADC CFIFO Status Snapshot Registers 0–2 (EQADC_CFSSRn).”
Table 19-44. CFIFO Scan Trigger Mode—Command Transfer Start/Stop Summary
Trigger Mode
Requires
Asserted SSS
to Recognize
Trigger
Events?
Command Transfer
Start/Restart Condition
Stop on
asserted
EOQ
bit
1
?
1
Refer to Section 19.4.3.6.2, “Command Queue Completion Status,” for more information on EOQ.
Stop on
asserted
Pause
bit
2
?
2
Refer to Section 19.4.3.6.3, “Pause Status,” for more information on pause.
Other Command Transfer Stop
Condition
3
4
3
The eQADC always stops command transfers from a CFIFO when the CFIFO operation mode is disabled.
4
The eQADC always stops command transfers from a CFIFO when a higher priority CFIFO is triggered. Refer to
Section 19.4.3.2, “CFIFO Prioritization and Command Transfer,” for information on CFIFO priority.
Single Scan
Software
Not Applicable Asserted SSS bit. Yes No None.
Single Scan
Edge
Yes A corresponding edge
occurs when the SSS bit
is asserted.
Yes Yes None.
Single Scan
Level
Yes Gate is opened when the
SSS bit is asserted.
Yes No The eQADC also stops transfers
from the CFIFO when CFIFO
status changes from triggered
due to the detection of a closed
gate.
5
5
If a closed gate is detected while no command transfers are taking place, it will have immediate effect on the CFIFO
status. If a closed gate is detected during the serial transmission of a command to the external device, it will have no
effect on the CFIFO status until the transmission completes.
Continuous
Scan Software
No CFIFO starts
automatically after being
configured into this mode.
No No None.
Continuous
Scan Edge
No A corresponding edge
occurs.
Yes Yes None.
Continuous
Scan Level
No Gate is opened. No No The eQADC also stops transfers
from the CFIFO when CFIFO
status changes from triggered
due to the detection of a closed
gate.
5
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