Enhanced Queued Analog-to-Digital Converter (eQADC)
MPC5566 Microcontroller Reference Manual, Rev. 2
Freescale Semiconductor 19-71
Continuous-Scan Level Trigger
When high or low level gated trigger mode is selected, the input level on the associated trigger signal
places the CFIFO in a TRIGGERED state. When high-level gated trigger is selected, a high-level signal
opens the gate, and a low level closes the gate. The CFIFO commands start to be transferred when the
CFIFO becomes the highest priority CFIFO using an available on-chip ADC or an external buffer that is
not full. Although command transfers do not stop upon detection of an asserted EOQ bit at the end of a
command transfer, the EOQF is asserted and, if enabled, an EOQ interrupt request is generated.
The eQADC stops transferring commands from a triggered CFIFO when CFIFO status changes from
triggered due to the detection of a closed gate. If a closed gate is detected while no command transfers are
taking place and the CFIFO status is TRIGGERED, the CFIFO status is immediately changed to waiting
for trigger and the PF flag is asserted. If a closed gate is detected during the serial transmission of a
command to the external device, it has no effect on the CFIFO status until the transmission completes.
After the transmission is completed, the TC_CF counter is updated, the PF flag is asserted, and the CFIFO
status is changed to waiting for trigger. Command transfers restart as the gate opens.
If the gate closes and opens during the same serial transmission of a command to the external device, it
has no affect on the CFIFO status or on the PF flag, but the TORF flag asserts as shown in Figure 19-40.
Therefore, closing the gate for a period less than a serial transmission time interval does not guarantee that
command transfers from a CFIFO are closed.
The pause bit has no effect in continuous-scan level trigger mode.
19.4.3.5.4 CFIFO Scan Trigger Mode Start/Stop Summary
Table 19-44 summarizes the start and stop conditions of command transfers from CFIFOs for all of the
single-scan and continuous-scan trigger modes.
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
?
Stop on
asserted
Pause
bit
2
?
Other Command Transfer Stop
Condition
3
4
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
Continuous
Scan Software
No CFIFO starts
automatically after being
configured into this mode.
No No None.
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