NXP Semiconductors MPC5644A, Reference Manual, Page: 1115 / 1735

Enhanced Queued Analog-to-Digital Converter (EQADC)
MPC5644A Microcontroller Reference Manual, Rev. 6
Freescale Semiconductor 1115
Figure 25-70. External CBuffer Status Detection at Command Sequence Transfer Start
Once a command sequence starts to be transferred, the EQADC will check for the command sequence
coherency until the command sequence ends or until one of the conditions below becomes true.
• The command sequence became non-coherent.
• The CFIFO status changed from TRIGGERED.
• The CFIFO underflowed.
NOTE
The NCF flag still becomes asserted if an external CBuffer empty event is
detected at the same time the EQADC stops checking for the coherency of
a command sequence.
Once command transfers restart/continue, the non-coherency hardware will behave as if the command
sequence started from that point.
Figure 25-73 depicts how the non-coherency hardware will behave when
a non-coherency event is detected.
NOTE
If MODEx is changed to disabled while a CFIFO is transferring commands,
the NCF flag for that CFIFO will not become asserted.
NOTE
When the EQADC enters debug or stop mode while a command sequence
is being executed, the NCF will become asserted if an empty external
CBuffer is detected after debug/stop mode is exited.
Null Message
1st Command 2nd Command 3rd Command
SDS
Serial Data
(a) (b) (c)
External CBuffer Status
Capture
Point at
EQADC
CBuffer
Status at
External
Device
CBuffer
Status as
Captured by
the EQADC
Used for
NCF
detection
on the
EQADC?
(a) EMPTY EMPTY Don’t care
(b) 1 ENTRY EMPTY No
Transmitted
Assumptions:
1. The CFIFO starts sending commands to an empty
external CBuffer when triggered.
2. Execution of a command on the external device
takes longer than the time to complete three serial
transmissions.
External CBuffer status starts to
be monitored here. Transfer of command
sequence starts