DrdybCase3: Routing DRDYB to D6
30139591
FIGURE 26. DrdybCase3 Connection Diagram
The drdyb signal can be routed to pin D6 by setting
SPI_DRDYB_D6 high and SDO_DRDYB_DRIVER to 0x4.
This is the behavior for DrdybCase3 as shown in Figure 26.
The timing protocol for this case can be seen in Figure 27.
Since DRDYB is separated from SDO, it can be monitored
using the interrupt or polling method. If polled, the drdyb signal
needs to be polled faster than t
DRDYB
to detect a drdyb as-
sertion. When drdyb asserts, assert CSB to start the SPI
transaction and begin writing the Instruction Bytes (INST1,
UAB, INST2) to read from or write to registers.
30139589
FIGURE 27. Timing Protocol for DrdybCase3
16.5.7 Data Only Read Transaction
In a data only read transaction, one can directly access the
data byte(s) as soon as the CSB is asserted without having
to send any instruction byte. This is useful as it brings down
the latency as well as the overhead associated with the in-
struction byte (as well as the Upper Address Byte, if any).
In order to use the data only transaction, the device must be
placed in the data first mode. The following table lists trans-
action formats for placing the device in and out of the data first
mode and reading the mode status.
TABLE 5. Data First Mode Transactions
Bit[7] Bits[6:5] Bit[4] Bits[3:0] Data Bytes
Enable Data First Mode Instruction 1 11 1 1010 None
Disable Data First Mode Instruction 1 11 1 1011 None
Read Mode Status Transaction 1 00 1 1111 One
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