User Manual

PNI Sensor Corporation Doc 1017252 r04

RM3100 & RM2100 Sensor Suite User Manual Page 35 of 45

5.4 Confirm New Data Ready

There are several ways to determine if a measurement has been completed and data is

available in the Measurement Results Registers. One method is monitoring the DRDY line

for it to go HIGH. Recall that for continuous measurement mode, the DRDM bits of the

Continuous Measurement Command byte establish the conditions for DRDY to go HIGH.

Another option when using the SPI interface is monitoring the MISO pin for it to go HIGH.

(The MISO pin is unavailable when using the I

C interface, as it is used to set the slave

address of the device.) Another option is to read from the STATUS register, as discussed

below. Only one method need be used.

5.4.1 STATUS Register (0x34)

To read the Status Register, first send a read command to the STATUS register, 0xB4.

The return byte provides the contents of the Status Register:

Bit #

Value

DRDY

Bit 7 will be HIGH if data is available and LOW if it is unavailable. Bits 0 – 6 are

indeterminate and should be ignored.

5.5 Read the Measurement Results

Each sensor reading consists of 3 bytes of data which are stored in 2‟s complement format

(range: -8388608 to 8388607) in the Results Registers within the MagI2C and this number is

directly proportional to the strength of the local magnetic field in the direction of the

specified axis. Note that the greater the Period Select value, the higher the resolution of the

measurement and the longer the sample time. These registers are read by sending the Read

Results byte, as defined below, where the values of A, B, C, and D establish the register to be

addressed, as given in Table 5-8.

Bit #

Value