Enhanced Queued Analog-to-Digital Converter (EQADC)
MPC5644A Microcontroller Reference Manual, Rev. 6
1114
Freescale Semiconductor
A command sequence is non-coherent when, after transferring the first command of a sequence from a
CFIFO to a CBuffer, it cannot successively send all the other commands of the sequence before any of the
following conditions are true:
•
The CFIFO through which commands are being transferred is preempted by a higher priority
CFIFO which sends commands to the same CBuffer. The NCF flag becomes asserted immediately
after the first command transfer from the preempting CFIFO, that is the higher priority CFIFO, to
the CBuffer in use is completed. See
•
The external CBuffer in use becomes empty
1
. This case happens when different CFIFOs attempt
to use different external CBuffers and the higher priority CFIFO bars the lower priority one from
sending new commands to its CBuffer - see
. An external CBuffer is considered empty
when the corresponding BUSY field in the last result message received from external device is
encoded as “Send available commands - CBuffer is empty”. Refer to
Format for External Device Operation
. The NCF flag becomes asserted immediately after the
EQADC detects that the external CBuffer in use becomes empty.
NOTE
After the transfer of a command sequence to an external CBuffer starts, the
EQADC ignores, for non-coherency detection purposes, the BUSY fields
captured at the end of the first serial transmission. Thereafter, all BUSY
fields captured at the end of consecutive serial transmissions are used to
check the fullness of that external CBuffer. This is done because the
EQADC only updates its external CBuffers status record when it receives a
serial message, resulting that the record kept by the EQADC is always
outdated by, at least, the length of one serial transmission. This prevents a
CFIFO from immediately becoming non-coherent when it starts transferring
commands to an empty external CBuffer. Refer to
for an
example.
1.
Only the fullness of external CBuffers is monitored because the fill rate for internal CBuffers is many times faster than the
drain rate, and each has a dedicated priority engine.
Summary of Contents for MPC5644A
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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...