MPC563XM Reference Manual, Rev. 1
1020
Freescale Semiconductor
Preliminary—Subject to Change Without Notice
The size of the CFIFO header is fixed to 6 bits, and it works as inputs to the
FIFO Control Unit
. It controls
when a CQueue ends, when it pauses, if commands are sent to internal or external buffers, and if it can
abort a serial data transmission. Information contained in the CFIFO header, together with the upper bit of
the ADC Command is used by the
FIFO Control Unit
to arbitrate which triggered CFIFO will transfer the
next command. ADC commands are encoded inside the least significant 26 bits of the command message.
A Result message is composed of an RFIFO header and an ADC Result. The
FIFO Control Unit
decodes
the information contained in the RFIFO header to determine the RFIFO to which the ADC result should
be sent. An ADC result is always 16 bits long.
24.6.2.3.1
Message Formats for On-Chip ADC Operation
This section describes the Command/Result message formats used for on-chip ADC operation.
NOTE:
Although this subsection describes how the command and result messages are
formatted to communicate with the on-chip ADCs, nothing prevents the
programmer from using a different format when communicating with an external
device through the serial interface. Refer to
Section 24.6.2.3.2, “Message Formats
. Apart from the BN bit, the ADC Command of a
command message can be formatted to communicate to an arbitrary external device
provided that the device returns an RFIFO header in the format expected by the
EQADC. When the FIFO Control Unit receives return data message, it decodes the
message tag field and stores the 16-bit data into the corresponding RFIFO.
Conversion Command Format for the Standard Configuration
describes the format for conversion commands when interfacing with the on-chip ADCs in
the standard configuration. The standard configuration is selected when the lowest byte (bits 24-31) of the
conversion command is set to zero. In the standard configuration, the conversion result is always routed
to one of the RFIFOs. A time stamp information can be optionally requested.
Figure 24-48. Conversion Command Format for the Standard Configuration
EOQ — End Of Queue Bit
The EOQ bit is asserted in the last command of a CQueue to indicate to the EQADC that a scan of the
CQueue is completed. EOQ instructs the EQADC to reset its current CFIFO transfer counter value
(TC_CF) to zero. Depending on the CFIFO mode of operation, the CFIFO status will also change upon
the detection of an asserted EOQ bit on the last transferred command - see
for details.
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
EOQ PAU
SE
REP
RESERVE
D
EB
(0b0)
BN
CAL
MESSAGE_TAG
LST
TSR FMT
CFIFO Header
ADC Command
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
CHANNEL_NUMBER
0
0
0
0
0
0
0
0
ADC Command