PNI RM3100 Sensor Suite - Manual (Page 41)

PNI Sensor Corporation Doc 1017252 r03
RM3100 & RM2100 Sensor Suite User Manual Page 40 of 45
The steps to make measurements in Continuous Measurement Mode are given below.
Start with SSN set HIGH, then set SSN to LOW.
Initiate Continuous Measurement Mode by writing to the CMM register address,
0x01, followed by the CMM register value. This value defines which axes are to
be measured, how the DRDY line will be set HIGH, and which type of Alarm will
be implemented assuming the Alarm feature is being utilized. Assuming all 3
axes are to be measured, DRDY goes HIGH after completing measurements on
all axes, and the Alarm feature is not utilized, the CMM value would be 0x79.
The RM3100 Evaluation Board will now initiate Continuous Measurement Mode.
Return SSN to HIGH. This will not affect the measurement process, but will free
up the host to communicate with other devices and ensure the next write
command sent to the module is interpreted properly.
Once the measurement sequence is completed on all axes the MISO pin goes low
and the DRDY pin is set HIGH, assuming 0x79 is the CMM register value. The
module will be placed in Idle Mode until it is time to take another measurement,
as defined by the TMRC register.
When the host is ready to read the measured values, set SSN to LOW. If SSN
already is LOW, then toggle SSN from LOW to HIGH to LOW.
Assuming the X axis was one of the axes to be measured, send the MX2 Read
address, 0xA4, to begin reading the Measurement Results registers. The
measurement readings will now clock out, with the 3 bytes of X-axis data
presented first, then Y-axis data, then Z-axis data. The first nine (9) bytes
represent a complete 3-axis measurement. This will clear the DRDY line.
Return SSN to HIGH to free up the host to communicate with other devices and
to ensure the next Command Byte sent to the module is interpreted properly.
The steps to make a single measurement are given as follows.
Start with SSN set HIGH, then set SSN to LOW.
Initiate a single measurement by writing to the POLL register address, 0x00,
followed the register address with either the POLL register value. This defines
which axes are to be measured, and should be 0x70 if measurements on all three
axes are desired.
The MagI2C will now take the prescribed measurements.
Return SSN to HIGH. This will not affect the measurement process, but will free
up the host to communicate with other devices and ensure the next write
command sent to the MagI2C is interpreted properly.