M-G362 Datasheet, PDF (21/69 Pages) Epson Company – IMU (Inertial Measurement Unit)

5.6 Sampling Counter
By reading COUNT[0x0A(W0)] register, the counter value can be read which is incremented based on
the sampling completion timing of the internal A/D converter. The count interval is 250usec/count and is
based on the precision of the internal reference oscillator (crystal).
Additionally, during UART/SPI burst mode and in UART Auto mode, the counter value can be included
in the normal response by setting the COUNT_OUT (BURST_CTRL1[0x0C(W1)] bit[1]). For information
about the response format, see 6.3 DATA PACKET FORMAT.
5.7 GPIO
The device has three general purpose I/O ports (GPIO). By accessing the GPIO[0x08(W0)] register, the
direction (in/out) of each port can be configured and data can be read/written to. The GPIO port can be
read in the normal mode, and also in the UART burst mode or UART auto mode.
GPIO1 is shared with the Data Ready signal. The switch between GPIO1 and Data Ready signal can be
controlled by DRDY_ON of MSC_CTRL[0x02(W1)] bit[2] register. When DRDY_ON is written as “0”,
GPIO1 act as general purpose I/O port.
GPIO2 is shared with EXT signal (External Trigger Input or External Counter Reset). The switch of
GPIO2 and EXT signal can be controlled by EXT_SEL of MSC_CTRL[0x02(W1)] bit[7:6] register. When
EXT_SEL is written as “00”, GPIO2 act as general purpose I/O port.
5.8 Self Test
The self test function can be used to check whether the outputs of the gyroscope and the accelerometer
are within the pre-determined range and operating properly. For the gyroscope, the test result is OK if
the bias of the output for each X-, Y-, or Z-axis is close to zero when the device is not moving. For the
accelerometer, the test result is OK if the absolute value of the output as a three dimensional vector is
equal to the gravitational acceleration. When performing the self test, make sure the device does not
move during the test and the test is conducted in a place without vibration.
For information about the execution time of the self test, see “Self Test Time” in Table 2.4 Interface
Specifications.
To use the self test function, see the description of the SELF_TEST (MSC_CTRL[0x02(W1)] bit[10])
and the ST_ERR_ALL (DIAG_STAT[0x04(W0)] bit[1]).
5.9 External Trigger Input
External Trigger Input function provides control of the sample data output timing by using an externally
supplied input pulse signal to GPIO2 (EXT) pin. By enabling the EXT_SEL (MSC_CTRL[0x02(W1)]
bit[7:6]), GPIO2 pin can be used as External Trigger Input pin. The polarity of External Trigger Input
(Positive Pulse / Negative Pulse) can be selected by EXT_POL (MSC_CTRL[0x02(W1)] bit[5]).
When this function is active, the operation is as follows:
• For UART Auto Mode:
When External Trigger Input pin is asserted, the latest sampling data is set to each register and
sent to Host automatically.
• For all other modes:
When External Trigger Input pin is asserted, the latest sampling data is set to each register and
Data Ready signal is asserted. The Host should then read the sampling data syncronized with
M-G362PDC1 Data Sheet
Seiko Epson Corporation
17
Rev.20131217