PNI RM3100 Sensor Suite - Manual (Page 31)

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RM3100 & RM2100 Sensor Suite User Manual Page 30 of 45
Table 5-3: Continuous Mode DRDY Options
DRDY Requirements DRDM1 DRDM0
DRDY to HIGH when ALARM = 1, AND a full
measurement sequence is completed, as
established by CMX, CMY, and CMZ.
0 0
DRDY to HIGH after the completion of a
measurement on any axis.
0 1
DRDY to HIGH after a full measurement
sequence is completed, as established by
CMX, CMY, and CMZ.
1 0
DRDY to HIGH when Alarm = 1. 1 1
CMX, CMY, CMZ – A “1” in either of these three bit positions indicates a
measurement will be taken on that sensor axis when operating in Continuous
Measurement Mode. For instance, to take measurements on all three axis, CMX =
CMY = CMZ = 1.
LDM – This bit indicates whether Absolute or Relative Alarm Mode is being
implemented. A “0” indicates Absolute Alarm Mode, while a “1” indicates Relative
Alarm Mode. See Section 5.2.2 for additional information.
To read from the CMM register, send 0x81. The return byte will provide the same
information as above, specifically indicating if ALARM is HIGH.
Note: Certain commands, such as reading from the CMM register or writing to the TMRC register,
will terminate Continuous Measurement Mode.
5.2.1 Setting the CMM Update Rate with TMRC (0x0B)
The time between measurements in Continuous Measurement Mode is established with
the TMRC register. The TMRC register is defined below.
Bit # 7 6 5 4 3 2 1 0
Value 1 0 0 1 TMRC3 TMRC2 TMRC1 TMRC0
The LSB is used set the CMM updatee rate. The MSB should be 0x9, as indicated above.
The larger the TMRC value, the longer the interval between measurements. Available
data rates are given in Table 5-4. Note that the update rates are approximate, and have a
one standard deviation tolerance of about ~7%. The default value for TMRC is 0x96,
establishing a data update rate of ~37 Hz.