ADIS16445 Datasheet, PDF (16/24 Pages) Analog Devices – Compact, Precision Six Degrees of Freedom Inertial Sensor

ADIS16445
INPUT/OUTPUT CONFIGURATION
DATA READY INDICATOR
The data ready indicator provides a signal that indicates
when the registers are updating, so that system processors can
avoid data collision, a condition when internal register updates
happen at the same time that an external processor requests it.
The data ready signal has valid and invalid states. Using the
transition from invalid to valid to trigger an interrupt service
routine provides the most time for data acquisition (before
the next register update). See Figure 4 and Table 2 for specific
timing information.
MSC_CTRL[2:0] (see Table 24) provide control bits for
enabling this function, selecting the polarity of the valid state
and I/O line assignment (DIO1, DIO2). The factory default
setting of MSC_CTRL[2:0] = 110 establishes DIO1 as a data
ready output line and assigns the valid state with a logic high
(1). Set MSC_CTRL[2:0] = 100 (DIN = 0xB404) to change the
polarity of the data ready signal on DIO1 for interrupt inputs
that require negative logic inputs for activation.
GENERAL-PURPOSE INPUT/OUTPUT
DIO1, DIO2, DIO3, and DIO4 are configurable, general-purpose
input/output lines that serve multiple purposes. The data
ready controls in MSC_CTRL[2:0] have the highest priority
for configuring DIO1 and DIO2. The alarm indicator controls in
ALM_CTRL[2:0] have the second highest priority for configuring
DIO1 and DIO2. The external clock control associated with
SMPL_PRD[0] has the highest priority for DIO4 configuration
(see Table 28). GPIO_CTRL in Table 27 has the lowest priority
for configuring DIO1, DIO2, and DIO4, and has absolute
control over DIO3.
Data Sheet
Table 27. GPIO_CTRL (Base Address = 0x32), Read/Write
Bits
Description (Default = 0x0000)
[15:12] Not used
11
General-Purpose I/O Line 4 (DIO4) data level
10
General-Purpose I/O Line 3 (DIO3) data level
9
General-Purpose I/O Line 2 (DIO2) data level
8
General-Purpose I/O Line 1 (DIO1) data level
[7:4]
Not used
3
General-Purpose I/O Line 4 (DIO4) direction control
1 = output, 0 = input
2
General-Purpose I/O Line 3 (DIO3) direction control
1 = output, 0 = input
1
General-Purpose I/O Line 2 (DIO2) direction control
1 = output, 0 = input
0
General-Purpose I/O Line 1 (DIO1) direction control
1 = output, 0 = input
Example Input/Output Configuration
For example, set GPIO_CTRL[3:0] = 0100 (DIN = 0xB204)
to set DIO3 as an output signal pin and DIO1, DIO2, and
DIO4 as input signal pins. Set the output on DIO3 to 1 by
setting GPIO_CTRL[10] = 1 (DIN = 0xB304). Then, read
GPIO_CTRL[7:0] (DIN = 0x3200) and mask off GPIO_CTRL[9:8]
and GPIO_CTRL[11] to monitor the digital signal levels on
DIO4, DIO2, and DIO1.
Rev. A | Page 16 of 24