MPC5553/MPC5554 Microcontroller Reference Manual, Rev. 5
19-14 Freescale Semiconductor
NOTE
When disabling the eQADC SSI, the FCK will not stop until it reaches its
low phase.
19.3.2.2 eQADC Null Message Send Format Register (EQADC_NMSFR)
The EQADC_NMSFR defines the format of the null message sent to the external device.
NOTE
The eQADC null message send format register only affects how the eQADC
sends a null message, but it has no control on how the eQADC detects a null
message on receiving data. The eQADC detects a null message by decoding
the MESSAGE_TAG field on the receive data. Refer to Table 19-34 for
more information on the MESSAGE_TAG field.
NOTE
Writing to the eQADC null message send format register while serial
transmissions are enabled is not recommended (See EQADC_MCR[ESSIE]
field in Section 19.3.2.1).
0123456789101112131415
R000000 NMF
W
Reset0000000000000000
Reg Addr Base + 0x0008
16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
RNMF
W
Reset0000000000000000
Reg Addr Base + 0x0008
Figure 19-3. eQADC Null Message Send Format Register (EQADC_NMSFR)
Table 19-4. EQADC_NMSFR Field Descriptions
Bits Name Description
0–5 — Reserved.
6–31 NMF
[0:25]
Null message format. Contains the programmable null message send value for the
eQADC. The value written to this register will be sent as a null message when serial
transmissions from the eQADC SSI are enabled (ESSIE field is configured to 0b11 in
EQADC_MCR (Section 19.3.2.1)) and either
• there are no triggered CFIFOs with commands bound for external command buffers, or;
• there are triggered CFIFOs with commands bound for external command buffers but the
external command buffers are full.
Refer to the section “Null Message Format for External Device Operation” for more
information on the format of a null message.
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