User Manual RM3000 & RM2000 Geomagnetic Sensor Suite
Table of Contents 1 2 3 4 5 6 COPYRIGHT & WARRANTY INFORMATION ............................................................ 4 INTRODUCTION .......................................................................................................... 5 SPECIFICATIONS ....................................................................................................... 6 3.1 GEOMAGNETIC SENSOR SUITE CHARACTERISTICS .............................. 6 3.2 SEN-XY AND SEN-Z CHARACTERISTICS........................
List of Figures Figure 3-1: Sample Rate vs. Resolution – Standard Mode ...................................................... 9 Figure 3-2: Gain vs. Cycle Counts – Standard & Legacy Modes ........................................... 10 Figure 3-3: Single-Axis Sample Rate vs. Cycle Counts – Standard & Legacy Modes .......... 10 Figure 3-4: Gain vs. Cycle Counts – Standard Mode ............................................................. 11 Figure 3-5: Single-Axis Sample Rate vs.
1 Copyright & Warranty Information © Copyright PNI Sensor Corporation 2010 All Rights Reserved. Reproduction, adaptation, or translation without prior written permission is prohibited, except as allowed under copyright laws. Revised July 2012: for the most recent version visit our website at www.pnicorp.com PNI Sensor Corporation 133 Aviation Blvd, Suite 101 Santa Rosa, CA 95403, USA Tel: (707) 566-2260 Fax: (707) 566-2261 Warranty and Limitation of Liability.
2 Introduction Thank you for purchasing PNI Sensor Corporation’s RM2000 or RM3000 Geomagnetic Sensor Suite (pn 90042 and pn 90043, respectively). The RM2000 is comprised of two Sen-XY Geomagnetic Sensors (pn 12683) and a 3D MagIC ASIC controller (pn 12927), and this forms the basis for a 2-axis digital compass. The RM3000 is the same as the RM2000 but adds a Sen-Z Geomagnetic Sensor (pn 12779), such that compassing measurements are not constricted to the horizontal plane.
3 Specifications 3.1 Geomagnetic Sensor Suite Characteristics Table 3-1: Geomagnetic Sensor Suite Performance1 Parameter Min Field measurement range 2 Gain @ 200 Cycle Counts Typical -1100 3 Max Units +1100 T 45 counts/ T 35 nT Maximum Sample Rate, Single Axis @ 4 200 Cycle Counts 450 Hz Linearity - best fit over 200 T 0.6 Average Current per Axis @ 35 Hz and 5 @ 200 Cycle Counts 0.3 Noise @ 200 Cycle Counts Bias Resistance (RB) 3 2.6 V to 3.3 V 68 1.6 V to 2.6V 33 + (V-1.
3.2 Sen-XY and Sen-Z Characteristics Table 3-2: Sen-XY and Sen-Z Absolute Maximum Ratings Parameter Minimum Maximum Units 50 mA +85 C Input Pin Current @ 25 C Storage Temperature -40 CAUTION: Stresses beyond those listed above may cause permanent damage to the device. These are stress ratings only. Assuming operation with the 3D MagIC per the guidelines in this manual, these maximum ratings will not be violated.
3.3 3D MagIC Characteristics Table 3-4: 3D MagIC 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° +125° C CAUTION: Stresses beyond those listed above may cause permanent damage to the device. These are stress ratings only.
3.4 Typical Sensor Suite Operating Performance Figure 3-1 plots typical gain-determined resolution as a function of the single axis sample rate. The plot starts at 300 Hz since the usable resolution is limited by best-case system noise of ~15 nT. The plot stops at 2400 Hz because this represents a cycle count of ~30, and operating at cycle counts much lower than this introduces significant quantization error. (The number of cycle counts is determined by the user, as explained in Sections 5.1 and 6.2.
000 Standard Mode Legacy Mode (default config.) Gain (counts/µT) 1000 100 10 1 0.1 10 100 1000 10000 Cycle Counts Figure 3-2: Gain vs. Cycle Counts – Standard & Legacy Modes Maximum Single-Axis Sample Rate (Hz) (Resolution = 1/Gain, to the system’s noise limit) 10000 Standard Mode Legacy Mode (default config.) 1000 100 10 1 10 100 1000 10000 Cycle Counts Figure 3-3: Single-Axis Sample Rate vs.
50 45 Gain (counts/µT) 40 35 30 25 20 15 10 5 0 0 20 40 60 80 100 120 140 160 180 200 Cycle Counts Figure 3-4: Gain vs. Cycle Counts – Standard Mode (Resolution = 1/Gain, to the system’s noise limit) Maximum Single-Axis Sample Rate (Hz) 3000 2700 2400 2100 1800 1500 1200 900 600 300 0 0 20 40 60 80 100 120 140 160 180 200 Cycle Counts Figure 3-5: Single-Axis Sample Rate vs.
Current Consumption @ 35 Hz Single-Axis Sample Rate (mA) 0.40 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0.00 0 20 40 60 80 100 120 140 160 180 200 Cycle Counts Figure 3-6: Current Consumption vs.
3.5 Dimensions and Packaging 3.5.1 Sen-XY Dimensions & Packaging Figure 3-7: Sen-XY Sensor Dimensions Note: PNI recommends using a 5 mil stencil and halide-free solder paste. Also, the above layout allows for rework: for minimal footprint please contact PNI.
Figure 3-9: Sen-XY Tape and Reel Dimensions 3.5.
Note: PNI recommends using a 5 mil stencil and halide-free solder paste. Also, the above layout allows for rework: for minimal footprint please contact PNI. Figure 3-11: Sen-Z Solder Pad Layout Dimensions: mm Full reel is 1200 pcs. Smaller quantities on cut-tape.
3.5.
User Direction of Unreeling Dimensions: mm Full reel is 600 pcs. Smaller quantities on cut-tape. Tape & Reel meets ANSI/EIA standard EIA-418 Figure 3-15: Sen-Z Shield Tape and Reel Dimensions 3.5.
Dimensions: mm Full reel is 5000 pcs. Smaller quantities on cut-tape. Tape & Reel meets ANSI/EIA standard EIA-418 Figure 3-17: 3D MagIC Tape Dimensions 3.6 Soldering Figure 3-18 and Table 3-6 provide the recommended solder reflow profile and processing parameters for Geomagnetic Sensor Suite components. After soldering PNI components to a board, it is possible to wave solder the opposite side of the PCB.
PB Figure 3-18: Recommended Solder Reflow Profile Table 3-6: Recommended Solder Processing Parameters1 Parameter Symbol Value Preheat Temperature, Minimum TSmin 150°C Preheat Temperature, Maximum TSmax 200°C 60 – 180 seconds Preheat Time (TSmin to TSmax) Solder Melt Temperature TL Ramp-Up Rate (TSmax to TL) Peak Temperature >218°C 3°C/second maximum TP Time from 25°C to Peak (TP) <260°C 6 minutes maximum Time above TL tL 60 – 120 seconds Soak Time (within 5°C of TP) tP 10 – 20 second
4 Geomagnetic Sensor Suite Overview & Set-Up 4.1 Overview Figure 4-1 provides a basic schematic for implementing the RM3000 Sensor Suite in Standard Mode. The 3D MagIC is at the center of the schematic, as it ties the user’s host controller, on the left, to the three Geomagnetic Sensors on the right. To implement the RM2000, simply do not connect the Sen-Z sensor. The 3D MagIC also can operate only one sensor if desired. Unused sensor connections should remain floating.
a comparator internal to the 3D MagIC. The sensor’s inductance varies with respect to the magnetic field. As such, the frequency of oscillation of the circuit varies with the strength of the total magnetic field parallel to the sensor. To make a measurement, one side of the sensor is grounded while the other side is alternately driven with positive and negative current through the oscillator.
4.2 Layout 4.2.1 Sensor Orientation Figure 4-3 indicates how the three Geomagnetic Sensors in a RM3000 Suite should be oriented for a system referenced as north-east-down (NED). The arrow represents the direction of travel or pointing. Positioning of the sensors is not critical, other than ensuring they are not positioned close to a magnetic component, such as a speaker.
accommodated. When the local magnetic field will change, try to take readings only when the field is in a known state. For instance, if a motor will be running part of the time, take readings only when the motor is in a known state (e.g. off). If you are uncertain about the effect a specific component may have on the system, the RM3000 Evaluation Board can be used to help ascertain this.
Table 4-1: 3D MagIC Pin Assignments Pin# Name Description 1 MOSI 2 NC 3 SSN SPI interface – Active low to select port 4 AVDD Supply voltage for analog section of ASIC 5 AVSS Ground pin for analog section of ASIC 6 ZDRVP Z sensor drive output 7 ZINP Z sensor measurement input 8 ZINN Z sensor measurement input 9 ZDRVN Z sensor drive output 10 YDRVP Y sensor drive output 11 YINP 12 MODE 13 YINN 14 YDRVN Y sensor drive output 15 XDRVP X sensor drive output 16 XINP X
Section 6). The MODE pin should be grounded (connected to DVSS) to operate in Standard Mode, and set HIGH (connected to DVDD) to operate in Legacy Mode. SCLK (SPI Serial Clock Input) SCLK is a SPI input used to synchronize the data sent in and out through the MISO and MOSI pins. SCLK is generated by the customer-supplied master device and should be 1 MHz or less. One byte of data is exchanged over eight clock cycles. Data is captured by the master device on the rising edge of SCLK.
DRDY (Data Ready) DRDY is used to ensure data is read from the 3D MagIC only when it is available. After initiating a sensor measurement, DRDY will go HIGH when the measurement is complete. This signals the host that data is ready to be read. The DRDY pin should be set LOW prior to initiating a measurement. This is done automatically in Standard Mode and by toggling the CLEAR pin in Legacy Mode.
REXT (External Timing Resistor) REXT ties to the external timing resistor for the high-speed clock. The recommended value for the resistor and associated clock speed are defined in Table 3-1. Sensor Drive and Measurement Pins The various sensor drive and measurement pins should be connected to the Geomagnetic Sensors. For a north-east-down (NED) reference frame, the connections should be as defined in Figure 4-3. 4.
Table 4-2: SPI Timing Specifications Symbol Description Min Time from SSN to CLEAR 10 ns tCMIN CLEAR duration 100 ns tSSDV Time from SSN to Command Byte on MOSI 1 us tDBSH Time to setup data before active edge 50 ns tDASH Time to setup data after active edge 50 ns tSHDZ Time from SSN to data tri-state time tSC Max 100 Units ns 4.
5 3D MagIC Operation – Standard Mode Note: This section discusses how to operate the 3D MagIC in Standard Mode. For a description of operation in Legacy Mode, see Section 6. The 3D MagIC operates in Standard Mode when pin #12 is held LOW (grounded to DVSS). The basic functions to be performed when operating the 3D MagIC are: Setting the values in the Cycle Count Registers, and Taking sensor measurements.
consumption. See Figure 3-4, Figure 3-5, and Figure 3-6 to estimate the appropriate cycle count value for your application. Once the Cycle Count Registers are set, they do not need to be repopulated unless the user wants to change the values or the system is powered down (in which case the default values would populate the register fields when powered up again).
Send 0 (value for the MSB for the X axis) Send 64H (value for the LSB for the X axis - pointer automatically increments) Send 0 (value for the MSB for the Y axis - pointer automatically increments) Send 64H (value for the LSB for the Y axis - pointer automatically increments) Send 0 (value for the MSB for the Z axis - pointer automatically increments) Send 64H (value for the LSB for the Z axis - pointer automatically increments) Set SSN to HIGH 5.
5.2.2 SAM Command Byte The SAM Command Byte is defined as follows: Bit # 7 6 5 4 3 2 Value 0 0 0 0 0 0 1 0 AS1 AS0 Table 5-2: SAM Axis Select Bits Axis Measured AS1 AS0 No axis measured 0 0 X axis 0 1 Y axis 1 0 Z axis 1 1 5.2.3 Making a Single-Axis Measurement The steps to make a single-axis sensor measurement are given below.
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 3D MagIC to output the measured values on the MISO line. 5.3.1 MAM SPI Activity Sequence The SPI timing sequence is given below for MAM operation. SPI timing is discussed in Section 4.4. The Return Byte is 9AH.
5.3.3 MAM Axes Select Byte The MAM Axes Select Byte establishes which axes are to be measured and is defined as follows: Bit # 7 6 5 Value 0 0 0 4 3 AAX1 AAX0 2 1 0 0 0 1 Table 5-3: MAM Axes Select Bits Axes Measured AAX1 AAX0 X, Y, and Z 0 0 X and Y 0 1 X only 1 0 No axis measured 1 1 5.3.4 Making a Multi-Axis Measurement The steps to make a multi-axis sensor measurement are given below.
Send C9H (MAM Command Byte to read from the ) on the MOSI pin to initiate reading the measurement values. Data is clocked out on the MISO pin. Each sensor reading consists of 3 bytes of data, clocked out MSB first. X-axis data is presented first, then y-axis data, then z-axis data. The first nine (9) bytes represent a complete 3-axis measurement. Return SSN to HIGH to free up the host to communicate with other devices and to ensure the next Command Byte sent to the 3D MagIC is interpreted properly.
6 3D MagIC Operation – Legacy Mode Note: This section discusses how to operate the 3D MagIC in Legacy Mode. For a description of operation in Standard Mode, see Section 5. The 3D MagIC will operate in Legacy Mode when pin #12 is held HIGH (connected to DVDD). The intent of Legacy Mode is to enable the user to easily substitute PNI’s 3D MagIC for PNI’s legacy 11096 ASIC (p/n 12576).
6.1.1 Legacy Operation SPI Activity Sequence The SPI activity sequence is given below for Legacy operation. SPI timing is discussed in Section 4.4. The Return Byte is 9BH. Two (2) data bytes will be clocked out for a Legacy measurement. The Command Byte is discussed below. Figure 6-1: SPI Activity Sequence Diagram for Legacy Operation 6.1.
Table 6-1: Legacy Period Select Bits Period Select Value Cycle Counts PS2 PS1 PS0 0 32 0 0 0 1 64 0 0 1 2 128 0 1 0 3 256 0 1 1 4 512 1 0 0 5 1024 1 0 1 6 2048 1 1 0 7 4096 1 1 1 AS0-AS1: Axis Select Determines the sensor to be measured. Table 6-2: Legacy Axis Select Bits Axis Measured AS1 AS0 No axis measured 0 0 X axis 0 1 Y axis 1 0 Z axis 1 1 6.1.3 Making a Legacy Measurement The steps to make a sensor measurement are given below.
The SSN input may be returned HIGH at this point to free up host communication with another device if desired. This will not affect the measurement process. A measurement is taken, which consists of forward biasing the sensor and making a period count; then reverse biasing the sensor and counting again; and then taking the difference between the two directions and presenting this value.
6.2.1 Clock Divide Command Byte The Command Byte to initiate reading or writing to the Clock Divide Register is defined as follows: Bit # 7 6 5 4 3 2 1 0 Value 1 R/W 0 0 0 0 0 0 R/W: Read/Write When HIGH signifies a Read operation from the Clock Divide Register. When LOW signifies a Write operation to the Clock Divide Register. 6.2.
6.2.3 Command Sequence for Setting Clock Divide Value A sample command sequence is given below which sets the Clock Divide Value to “1”. Set SSN to LOW. Send 80H (this is the Command Byte to write to the Clock Divide Register) Send 0 (this sets the Clock Divide Value to “1”) Set SSN to HIGH 6.2.4 Changes to the Period Select Value Since the high-speed clock is running faster, the time resolution of the measurement is increased.
