PNI RM3000-F Evaluation Board - Manual (Page 17)

PNI Sensor Corporation Doc #1016391 r04
RM3000-f Evaluation Board User Manual Page 16
5.3 Multi-Axis Measurement (MAM) Operation
An initial MAM Command Byte initiates a sensor measurement for up to 3 sensors. After
the measurements are made and the DRDY line goes HIGH, another MAM Command Byte
sets up the RM3000-f Evaluation Board to output the measured values on the MISO line.
See the Appendix for code examples.
5.3.1 MAM SPI Activity Sequence
The SPI activity sequence is given below for MAM operation. SPI timing is discussed in
Section 4.3. The Return Byte is 0x9A. The number of data bytes will be determined by
the number of axes that are to be measured. Each axis is comprised of 3 bytes of data, so
for a 3 axis measurement 9 total bytes would be clocked out to receive all the data. The
Command Byte and Axes Select Byte are discussed below.
Figure 5-2: SPI Activity Sequence Diagram for MAM Operation
5.3.2 MAM Command Byte
The initial MAM Command Byte is sent to set up the RM3000-f Evaluation Board to
take a sensor measurement and a different MAM Command Byte is later sent to initiate
reading the measurement results registers on the MISO line. The MAM Command Byte
is 0x82 to set-up for a sensor measurement and 0xC9 to retrieve the data starting at the X
axis. Note the initial Command Byte (0x82) does not actually initiate a sensor
measurement, as the measurement is initiated after the MAM Axes Select Byte is sent.