PNI RM3100 User manual

User Manual
RM3100 Evaluation Board
Geomagnetic Sensor Module

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Table of Contents
1COPYRIGHT & WARRANTY INFORMATION............................................................3
2INTRODUCTION..........................................................................................................4
3SPECIFICATIONS .......................................................................................................5
3.1 RM3100 EVALUATION BOARD CHARACTERISTICS..................................5
3.2 DIMENSIONS..................................................................................................7
4RM3100 EVALUATION BOARD OVERVIEW & SET-UP...........................................8
4.1 PCB ORIENTATION AND OUTPUT POLARITIES.........................................8
4.2 LOCAL MAGNETIC FIELD CONSIDERATIONS............................................8
4.3 RM3100 EVALUATION BOARD PIN ASSIGNMENTS...................................9
4.3.1 General Purpose Pins ........................................................................9
4.3.2 SPI Pins............................................................................................10
4.3.3 I2C Pins.............................................................................................11
4.4 SPI TIMING REQUIREMENTS.....................................................................12
4.5 I2C REQUIREMENTS....................................................................................14
4.5.1 I2C Register Write.............................................................................14
4.5.2 I2C Register Read.............................................................................15
5RM3100 EVALUATION BOARD OPERATION.........................................................16
5.1 SET THE CYCLE COUNT REGISTERS (0X04 –0X09)..............................17
5.2 INITIATE CONTINUOUS MEASUREMENT MODE (0X01)..........................18
5.2.1 Setting the CMM Update Rate with TMRC (0x0B)...........................19
5.2.2 Alarm Mode ......................................................................................20
5.3 INITIATE A SINGLE MEASUREMENT (0X00).............................................23
5.4 CONFIRM NEW DATA READY....................................................................24
5.4.1 STATUS Register (0x34)..................................................................24
5.5 READ THE MEASUREMENT RESULTS......................................................24
5.6 TROUBLESHOOTING AND GENERAL INFORMATION.............................25
5.6.1 BIST Register (0x33)........................................................................25
5.6.2 HSHAKE Register (0x35).................................................................26
5.6.3REVID Register (0x36).....................................................................27
5.7 EXAMPLES USING THE SPI INTERFACE..................................................27
5.7.1 Set the Cycle Count Registers .........................................................27
5.7.2 Making and Reading Measurements................................................28
5.8 EXAMPLES USING THE I2C INTERFACE...................................................30
5.8.1 Set the Cycle Count Registers .........................................................30
5.8.2 Initiate a Single Measurement..........................................................31
5.8.3 Initiate Continuous Measurement Mode...........................................31
5.8.4 Read the Measurement Results.......................................................31

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List of Figures
Figure 3-1: RM3100 Evaluation Board Mechanical Drawing ...................................................7
Figure 4-1: SPI Timing Diagram, CPOL = CPHA = 0.............................................................13
Figure 4-2: SPI Timing Diagram, CPOL = CPHA = 1.............................................................13
Figure 5-1: SPI Activity Sequence Diagram...........................................................................28
List of Tables
Table 3-1: Operating Performance...........................................................................................5
Table 3-2: Absolute Maximum Ratings ....................................................................................6
Table 3-3: Operating Conditions...............................................................................................6
Table 4-1: RM3100 Evaluation Board Pin Assignments ..........................................................9
Table 4-2: SPI Timing Specifications .....................................................................................14
Table 5-1: RM3100 Evaluation Board Register Map..............................................................16
Table 5-2: Cycle Count Registers...........................................................................................17
Table 5-3: Continuous Mode DRDY Options .........................................................................19
Table 5-4: CMM Update Rates...............................................................................................20
Table 5-5: Alarm Lower and Upper Limit Registers ...............................................................21
Table 5-6: Alarm Hysteresis Registers...................................................................................22
Table 5-7: Absolute vs. Relative Alarm Mode Example.........................................................23
Table 5-8: Measurement Results Registers...........................................................................25
Table 5-9: BIST Timeout Period.............................................................................................26
Table 5-10: BIST LR Periods..................................................................................................26

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1 Copyright & Warranty Information
© Copyright PNI Sensor Corporation 2013
All Rights Reserved. Reproduction, adaptation, or translation without prior written permission is prohibited, except as allowed under copyright laws.
Revised July 2013: for the most recent version visit our website at www.pnicorp.com
PNI Sensor Corporation
2331 Circadian Way
Santa Rosa, CA 95407, USA
Tel: [phone]
Fax: [phone]
Warranty and Limitation of Liability. PNI Sensor Corporation ("PNI") manufactures its Products from parts and components that are new or
equivalent to new in performance. PNI warrants that each Product to be delivered hereunder, if properly used, will, for ninety (90) days following the
date of shipment unless a different warranty time period for such Product is specified: (i) in PNI’s Price List in effect at time of order acceptance; or (ii)
on PNI’s web site (www.pnicorp.com) at time of order acceptance, be free from defects in material and workmanship and will operate in accordance
with PNI’s published specifications and documentation for the Product in effect at time of order. PNI will make no changes to the specifications or
manufacturing processes that affect form, fit, or function of the Product without written notice to the Customer, however, PNI may at any time, without
such notice, make minor changes to specifications or manufacturing processes that do not affect the form, fit, or function of the Product. This warranty
will be void if the Products’ serial number, or other identification marks have been defaced, damaged, or removed. This warranty does not cover wear
and tear due to normal use, or damage to the Product as the result of improper usage, neglect of care, alteration, accident, or unauthorized repair.
THE ABOVE WARRANTY IS IN LIEU OF ANY OTHER WARRANTY, WHETHER EXPRESS, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT
LIMITED TO, ANY WARRANTY OF MERCHANTABILITY, FITNESS FOR ANY PARTICULAR PURPOSE, OR ANY WARRANTY OTHERWISE
ARISING OUT OF ANY PROPOSAL, SPECIFICATION, OR SAMPLE. PNI NEITHER ASSUMES NOR AUTHORIZES ANY PERSON TO ASSUME
FOR IT ANY OTHER LIABILITY.
If any Product furnished hereunder fails to conform to the above warranty, Customer’s sole and exclusive remedy and PNI’s sole and exclusive liability
will be, at PNI’s option, to repair, replace, or credit Customer’s account with an amount equal to the price paid for any such Product which fails during
the applicable warranty period provided that (i) Customer promptly notifies PNI in writing that such Product is defective and furnishes an explanation of
the deficiency; (ii) such Product is returned to PNI’s service facility at Customer’s risk and expense; and (iii) PNI is satisfied that claimed deficiencies
exist and were not caused by accident, misuse, neglect, alteration, repair, improper installation, or improper testing. If a Product is defective,
transportation charges for the return of the Product to Customer within the United States and Canada will be paid by PNI. For all other locations, the
warranty excludes all costs of shipping, customs clearance, and other related charges. PNI will have a reasonable time to make repairs or to replace
the Product or to credit Customer’s account. PNI warrants any such repaired or replacement Product to be free from defects in material and
workmanship on the same terms as the Product originally purchased.
Except for the breach of warranty remedies set forth herein, or for personal injury, PNI shall have no liability for any indirect or speculative damages
(including, but not limited to, consequential, incidental, punitive and special damages) relating to the use of or inability to use this Product, whether
arising out of contract, negligence, tort, or under any warranty theory, or for infringement of any other party’s intellectual property rights, irrespective of
whether PNI had advance notice of the possibility of any such damages, including, but not limited to, loss of use, revenue or profit. In no event shall
PNI’s total liability for all claims regarding a Product exceed the price paid for the Product. PNI neither assumes nor authorizes any person to assume
for it any other liabilities.
Some states and provinces do not allow limitations on how long an implied warranty lasts or the exclusion or limitation of incidental or consequential
damages, so the above limitations or exclusions may not apply to you. This warranty gives you specific legal rights and you may have other rights that
vary by state or province.

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2 Introduction
Thank you for purchasing PNI Sensor Corporation’s RM3100 Evaluation Board, pn 13606. The
RM3100 Evaluation Board is a plug-and-play module (PCA) version of PNI’s RM3100
Geomagnetic Sensor, principally intended for quickly evaluating and prototyping PNI’s
magnetic sensor technology. The primary components of the RM3100 Evaluation Board are two
Sen-XY-f sensor coils, one Sen-Z-f sensor coil, and PNI’s MagI2C ASIC controller. It also
incorporates resistors, capacitors, and connectors, all mounted on a PCB, to provide a complete
magnetic field sensing module. The RM3100 Evaluation Board incorporates both I2C and SPI
interfaces for system design flexibility.
PNI’s geomagnetic sensor technology provides high resolution, low power consumption, large
signal noise immunity, a large dynamic range, and high sampling rates. Measurements are stable
over temperature and inherently free from offset drift. The RM3100 Evaluation Board features
both continuous measurement mode and single measurement polling, an alarm feature for
monitoring magnetic field strength, software-configurable resolution and sample rate, and the
ability to operate one, two, or all three PNI sensor coils. These advantages make PNI’s RM3100
Evaluation Board not only the choice for prototyping high volume solutions, but also for lower
volume applications that require a complete solution.
Each sensor coil of the RM3100 module serves as the inductive element in a simple LR
relaxation oscillation circuit, where the coil’s effective inductance is proportional to the magnetic
field parallel to the sensor axis. The LR circuit is driven by the MagI2C ASIC and the MagI2C’s
internal clock is used to measure the circuit’s oscillation frequency, and hence the magnetic field.
Since the RM3100 works in the frequency domain, resolution and noise are established cleanly
by the number of MagI2C internal clock counts (cycle counts). In comparison, fluxgate and MR
technologies require expensive and complex signal processing to obtain similar resolution and
noise, and in many respects the geomagnetic sensor’s performance simply cannot be matched.
Also, the output from the MagI2C is inherently digital and can be fed directly into a
microprocessor, eliminating the need for signal conditioning or an analog/digital interface
between the sensor and a microprocessor. The simplicity of PNI’s geomagnetic sensor combined
with the lack of signal conditioning makes it easier and less expensive to implement than
alternative fluxgate or magneto-resistive (MR) technologies.
For more information on PNI’s magneto-inductive sensor technology, see PNI’s whitepaper
“Magneto-Inductive Technology Overview” at http://www.pnicorp.com/technology/papers.

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3 Specifications
3.1 RM3100 Evaluation Board Characteristics
Table 3-1: Operating Performance1
Parameter
Cycle Counts2
Units
50
100
200
Field Measurement Range3
-800 to +800
T
Gain
20
38
75
LSB/ T
Sensitivity
50
26
13
nT
Noise
30
20
15
nT
Noise Density @ Max. Single-Axis Sample Rate
1.2
nT/ Hz
Repeatability over 200 T
15
8
8
nT
Hysteresis over 200 T
15
nT
Linearity over 200 T
0.5
%
Maximum Single-Axis Sample Rate
(divide by 3 for max. 3-axis sample rate)
1600
850
440
Hz
Single-Axis Average Current @ 24 Hz Sample
Rate (equivalent to 3-axis @ 8 Hz)
70
135
260
µA
Footnotes:
1. Specifications are typical and subject to change. Performance specifications established with 3.0
V supply voltage at room temperature.
2. The cycle count values (50 ,100, and 200) are user-configurable and set in the Cycle Count
Registers. See Section 5.1 for how to set the registers.
3. Field measurement range is defined as the monotonic region of the output characteristic curve.

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Table 3-2: Absolute Maximum Ratings
Parameter
Minimum
Maximum
Units
Analog/Digital DC Supply Voltage, AVDD & DVDD
-0.3
+3.7
VDC
Input Pin Voltage
-0.3
AVDD or DVDD
VDC
Input Pin Current @ 25C
-10.0
+10.0
mA
Storage Temperature
-40°
+85°
C
CAUTION:
Stresses beyond those listed above may cause permanent damage to the device. These
are stress ratings only. Operation of the device at these or other conditions beyond those
indicated in the operational sections of the specifications is not implied.
Table 3-3: Operating Conditions
Parameter
Min
Typ
Max
Units
Analog/Digital DC Supply Voltage, AVDD & DVDD1
2.0
3.0
3.6
VDC
Voltage Ripple on AVDD or DVDD
0.05
VPP
Idle Mode Current
1
µA
Leakage Current @ DVDD pin
(AVDD=AVSS=DVSS=0V, DVDD=3.6V)
100
nA
Operating Temperature
-40
+85
C
Footnote:
1. Please contact PNI if operation at <2.0 V is required.

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3.2 Dimensions
Figure 3-1: RM3100 Evaluation Board Mechanical Drawing

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4 RM3100 Evaluation Board Overview & Set-Up
This section provides an overview of how to set-up the RM3100 Evaluation Board and the basic
I2C and SPI communications requirements. For a discussion of PNI’s magneto-inductive sensor
technology, please refer to either the RM3100 Geomagnetic Sensor User Manual or PNI’s
whitepaper “Magneto-Inductive Technology Overview”, both of which can be found on PNI’s
website at www.pnicorp.com.
4.1 PCB Orientation and Output Polarities
The arrow printed on the RM3100 module indicates the intended line-of-sight. The RM3100
module is arranged in a north-east-down (NED) coordinate system, and the arrow is parallel
to the x-axis sensor. When the module is pointing directly magnetic south the x-axis reading
will be maximized and the y-axis will be zero. Likewise, when the module is pointing west
the y-axis reading will be maximized and the x-axis reading will be zero. The z-axis reading
will depend on the dip angle at the given location. At the geo-magnetic equator, where
Earth’s magnetic field is horizontal, the z-axis reading will be zero when flat.
4.2 Local Magnetic Field Considerations
Because the RM3100 sensor module measures magnetic field, it is important to consider
what items in the vicinity of the module can affect the sensor readings. Note that magnetic
field drops off as (1/distance)3. Specific issues to consider include:
The sensors have a specified linear regime of 200 T. (Earth’s field is ~50 T.) To
ensure the sensors operate in their linear regime, do not place the RM3100 close to
large electric currents, large masses of ferrous material, or devices incorporating
permanent magnets, such as speakers and electric motors.
Locate the RM3100 Eval Board away from changing magnetic fields. If this is not
possible, but the local magnetic field is known to have multiple states, try to take
readings only when the field is in a known state. For instance, if a motor runs part of
the time, take readings only when the motor is in a known state.
If you are uncertain about the effect a specific component may have on the system,
place the RM3100 Eval Board on a firm surface and gradually bring the component in
question close to the board, then note when the magnetic field starts to change. If the
component cannot be moved, then gradually move the RM3100 module towards the
component, carefully ensuring the orientation of the board remains constant while
doing this.

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4.3 RM3100 Evaluation Board Pin Assignments
The RM3100 Evaluation Board’s pin assignments are summarized below in Table 4-1. Pin
numbers run counterclockwise, when looking from the top, starting at the Pin 1 designator as
shown in Figure 3-1.
Table 4-1: RM3100 Evaluation Board Pin Assignments
Pin#
Pin Name
Description
1
SCK /
SCL
SPI interface (SCK) –Serial clock input
I2C interface (SCL) –Serial clock line
2
SO /
SA1
SPI interface (SO) –Master Input, Slave Output
I2C interface –Bit 1 of slave address
3
SI
SDA
SPI interface (SI) –Master Output, Slave Input Serial Data
I2C interface (SDA) –Serial Data Line
4
SSN /
SA0
SPI interface –Active low to select port
I2C interface –Bit 0 of slave address
5
DRDY
Status line
7
AVSS
Ground pin for analog section of ASIC
10
I2CEN
I2C enable pin (HIGH = I2C, LOW = SPI)
12
DVDD
Supply voltage for digital section of ASIC.
13
AVDD
Supply voltage for analog section of ASIC
14
DVSS
Ground pin for digital section of ASIC
6, 8, 9, 11
NC
Do not connect
4.3.1 General Purpose Pins
DVDD and AVDD (pins 12 & 13)
AVDD and DVDD should be tied to the analog and digital supply voltages,
respectively. The recommend voltages are defined in Table 3-3, and the maximum
voltages are given in Table 3-2. DVDD must be on whenever AVDD is on, so
DVDD should either be brought up first or at precisely the same time as AVDD.
AVDD can be turned off when not making a measurement to conserve power, since
all other operations are supported with DVDD. Under this condition, register values
will be retained as long as DVDD is powered. Also, AVDD must be within 0.1 V of
DVDD when AVDD is on.