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Enhanced Queued Analog-to-Digital Converter (EQADC)
MPC5644A Microcontroller Reference Manual, Rev. 6
Freescale Semiconductor
1075
interface with the EQADC. Some assumptions about the architecture of the external device are also
described.
25.6.2.2.1
EQADC SSI Protocol Support
The external device must fully support the EQADC SSI protocol as specified in
Synchronous Serial Interface (SSI) Sub-Block
.. Support for the abort feature is optional. When aborts are
not supported, all command messages bound for an external CBuffer must have the ABORT_ST bit
negated - see
Section , Command Message Format for External Device Operation
25.6.2.2.2
Number of Command Buffers and Result Buffers
The external device should have a minimum of one and a maximum of two Command Buffers (CBuffer)
to store command data sent from the EQADC. Even if more than two CBuffers are implemented in the
external device, they are not recognized by the EQADC as valid destinations for commands. In this
document, these two CBuffers will be referred as CBuffer2 and CBuffer3. The external device decides to
which external CBuffer a command should go by decoding the upper bit (BN bit) of the ADC command -
see
Section , Command Message Format for External Device Operation
. An external device that only
implements one CBuffer can ignore the BN bit.
The limit of two CBuffers does not limit the number of RBuffers in the slave device.
25.6.2.2.3
Command Execution and Result Return
Commands sent to an specific CBuffer should be executed in that order they were received.
Results generated by the execution of commands of a CBuffer should be returned in the order the CBuffer
received these commands.
25.6.2.2.4
Null and Result Messages
The external device must be capable of correctly processing null messages as specified in the
Section 25.5.2.3, EQADC null message send format register (EQADC_NMSFR)
In case no valid result data is available to be sent to the EQADC, the external device must send data in the
format specified in
Section , Null Message Format for External Device Operation
In case valid result data is available to sent to the EQADC, the external device must send data in the format
specified in
Section , Result Message Format for External Device Operation
.
The BUSY0/1 fields of all messages sent from the external device to the EQADC must be correctly
encoded according to the latest information on the fullness state of the CBuffers. For example, if the
CBuffer2 is empty before the end of the current serial transmission and if at the end of this transmission
the external device receives a command to CBuffer2, then the BUSY0 field, that is to be sent to the
EQADC on the next serial transmission, should be encoded assuming that CBuffer2 has one entry.
25.6.2.3
Message Format in EQADC
This section explains the command and result message formats used for on-chip ADC operation and for
external device operation.
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...