User Manual

Apollo3 Blue Datasheet
DS-A3-0p9p1 Page 276 of 909 2019 Ambiq Micro, Inc.
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Figure 33. SPI Normal Read Operation
As with a Normal Write, the Offset Address byte including the RW bit is taken from the offset field(s) of
CMD. If the slave expects an RW bit, the msb of the offset must be set accordingly. This allows reads from
devices which have different formats for the address byte.
8.8.5 SPI Raw Write
If a Raw Write is selected in the OPER field, the operation is similar to a Normal Write but the Offset
Address byte is not sent and all data comes directly from the FIFO as shown in Figure 34. The OFFSET
field is not used in this case.
Figure 34. SPI Raw Write Operation
8.8.6 SPI Raw Read
If a Raw Read is selected in the OPER field, the operation is simply the data transfer portion of a Normal
Read. All data goes directly to the FIFO as shown in Figure 35. The OFFSET field is not used in this case.
Figure 35. SPI Raw Read Operation
R 6 1
MOSI
SCK
0
Offset Address
nCE
X
Data Byte N Data Byte N+1
7 6 1 0 7 6 1 0
MISO
X5 4 3 2
5 4 3 2 5 4 3 2
7 6 1
MOSI
SCK
0 7 6 1 0
nCE
X 7 6 1 0
Data Byte N+2
X
MISO
5 4 3 2 5 4 3 2 5 4 3 2
Data Byte N+1Data Byte N
MOSI
SCK
nCE
Data Byte N+2
7 6 1 0 7 6 1 0
MISO
5 4 3 2 5 4 3 2
Data Byte N+1
7 6 1 05 4 3 2
Data Byte N