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Enhanced Queued Analog-to-Digital Converter (EQADC)
MPC5644A Microcontroller Reference Manual, Rev. 6
1100
Freescale Semiconductor
messages from the external device - see
Section , Result Message Format for External Device Operation
,
for details.
NOTE
When a lower priority CFIFO is served first because a higher priority
CFIFO cannot send its commands due to a full external CBuffer, there is a
possibility that command transfers from the lower priority CFIFO will be
interrupted and the CFIFO will become non-coherent, when the higher
priority CFIFO again becomes ready to send commands. If the lower
priority CFIFO becomes non-coherent or not depends on the rate at which
commands on the external CBuffers are executed, on the rate at which
commands are transmitted to the external CBuffers, and on the depth of
those buffers.
Once a serial transmission is started, the sub-block monitors triggered CFIFOs and manages the abort of
serial transmissions. In case a null message is being transmitted, the serial transmission is aborted when
all following conditions are met:
•
A not-underflowing CFIFO in TRIGGERED state has commands bound for an external CBuffer
that is not full, and it is the highest priority CFIFO sending commands to an external CBuffer that
is not full.
•
the ABORT_ST bit of the command to be transmitted is asserted.
•
the 26th bit of currently transmitting null message has not being shifted out.
The command from the CFIFO is then written into EQADC SSI transmit buffer, allowing for a new serial
transmission to initiate.
In case a command is being transmitted, the serial transmission is aborted when all following conditions
are met:
•
CFIFO0 is in TRIGGERED state, is not underflowing, and its current command is bound for an
external CBuffer that is not full.
•
the ABORT_ST bit of the command to be transmitted is asserted.
•
the 26th bit of currently transmitting command has not being shifted out.
The command from CFIFO0 is then written into EQADC SSI transmit buffer, allowing for a new serial
transmission to initiate.
NOTE
The aborted command is not popped from the preempted CFIFO and will be
retransmitted as soon as its CFIFO becomes the highest priority CFIFO
sending commands to an external CBuffer that is not full.
After a serial transmission is completed, the EQADC prioritizes the CFIFOs and schedules a command or
a null message to be sent in the next serial transmission. After the data for the next transmission has been
defined and scheduled, the EQADC can, under certain conditions, stretch the SDS negation time in order
to allow the schedule of new data for that transmission. This occurs when the EQADC acknowledges that
the status of a higher-priority CFIFO changed to TRIGGERED and attempts to schedule that CFIFO
Summary of Contents for MPC5644A
Page 2: ...MPC5644A Microcontroller Reference Manual Rev 6 2 Freescale Semiconductor...
Page 24: ...MPC5644A Microcontroller Reference Manual Rev 6 24 Freescale Semiconductor...
Page 26: ...MPC5644A Microcontroller Reference Manual Rev 6 26 Freescale Semiconductor...
Page 52: ...Introduction MPC5644A Microcontroller Reference Manual Rev 6 52 Freescale Semiconductor...
Page 56: ...Memory Map MPC5644A Microcontroller Reference Manual Rev 6 56 Freescale Semiconductor...
Page 1228: ...Decimation Filter MPC5644A Microcontroller Reference Manual Rev 6 1228 Freescale Semiconductor...
Page 1440: ...FlexCAN Module MPC5644A Microcontroller Reference Manual Rev 6 1440 Freescale Semiconductor...