User Manual SmartSens MicroMag Magneto-Inductive Sensor Module
Table of Contents 1 2 3 4 5 COPYRIGHT & WARRANTY INFORMATION ...............................................................4 INTRODUCTION .............................................................................................................5 SPECIFICATIONS ...........................................................................................................6 3.1 MODULE CHARACTERISTICS .......................................................................6 3.
List of Figures Figure 3-1: Figure 3-2: Figure 3-3: Figure 3-4: Figure 3-5: Figure 3-6: Figure 3-7: Figure 3-8: Figure 3-9: Figure 4-1: Figure 5-1: Figure 5-2: Temperature Characteristics................................................................... 7 Linearity vs. Temperature ....................................................................... 8 Linearity vs. Temperature, Normalized to Room Temperature ................ 8 MicroMag2 Mechanical Drawing.................................................
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 March 2010: 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 MicroMag magneto-inductive sensing module. Whether you purchased the MicroMag2 2-axis sensing module or the MicroMag3 3-axis sensing module, we’re sure you’ll be happy with your purchase. If you do have issues with your device, please feel free to contact us. The MicroMag is an integrated magnetic field sensing module combining PNI’s patented SmartSens magneto-inductive (MI) sensors with the PNI ASIC.
3 Specifications 3.1 Module Characteristics Table 3-1: Absolute Maximum Ratings Parameter Symbol Maximum Units DC Supply Voltage VDD 5.25 VDC Input Pin Voltage VIN VDD + 0.3 VDC Input Pin Current @ 25C IIN 10 mA mA TSTRG +85 C Storage Temperature CAUTION: Stresses beyond those listed in Table 3-1 may cause permanent damage to the device. These are stress ratings only.
applications, a sensor gain calibration is optimally performed when the sensor module is in the host system. 3) VDD = 3.0VDC 4) The sensor frequency is related to the strength of the magnetic field. The specified value is for when the MicroMag is solely within Earth’s magnetic field. 3.
Figure 3-2: Linearity vs. Temperature Figure 3-3: Linearity vs.
3.3 Mechanical Drawings ALL DIMENSIONS IN MM 3.3.
Figure 3-6: MicroMag2 3-D View with Component Call-Out Table 3-3: MicroMag2 Component Call-Out Item Number Quantity Description 1 1 MicroMag2 PCB 2 1 PNI ASIC, MLF package 3 2 SEN-XY 4 1 C1, chip capacitor 5 1 C2, chip capacitor 6 1 R1, chip resistor 7 1 R2, chip resistor 8 1 R3, chip resistor 9 1 R4, chip resistor 10 1 R5, chip resistor PNI Sensor Corporation MicroMag User Manual – March 2010 DOC# 1015175 r01 Page 10 of 23
3.3.
3.3.
4 Set-Up & Interface Lines 4.1 PCB Orientation and Output Polarities Both the MicroMag2-on-Carrier and MicroMag3 have an arrow printed on the PCB indicating the “reference direction” for the module, while the MicroMag2’s reference direction is shown in Figure 3-4. The sensors on the MicroMag modules are arranged in a south-west-down (SWD) coordinate system.
Table 4-1: Pin/Pad Indentifier Table Identifier MicroMag2-onMicroMag2 Carrier & Description Pad # MicroMag3 Pin # SCLK 1 13 Serial clock input for SPI port, 1 MHz maximum (Rext = 100 kHz) MISO 2 14 Master In, Slave Out for the SPI port MOSI 3 1 Master Out, Slave In for the SPI port SSNOT 4 2 Active low device select for SPI port DRDY 5 10 Data ready RESET 6 9 Reset input GND 7, 14 3, 5, 7 VDD 12 4, 6 DC supply voltage COMP NA 8 Comparator output DHST NA 11 High-speed
Figure 4-1: MicroMag2-on-Carrier Reference Block Diagram 4.3 Line Descriptions 4.3.1 SCLK (SPI Serial Clock) The serial clock input is used to synchronize both the data in and out through the MISO and MOSI lines. The serial clock signal is provided 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.
4.3.2 MISO (SPI Master In, Slave Out) An SPI output that sends data from the MicroMag module to the master device. Data is transferred most significant bit first. The MISO line is placed in a high impedance state if the MicroMag is not selected by the master device (SSNOT = 1). 4.3.3 MOSI (SPI Master Out, Slave In) An SPI input that provides data from the master device to the MicroMag module. Data is transferred most significant bit first.
Table 4-2: Maximum Delay for DRDY Period Select Maximum Delay 32 500 μS 64 1.0 mS 128 2.0 mS 256 4.0 mS 512 7.5 mS 1024 15 mS 2048 35.5 mS 4096 60 mS 4.3.6 RESET (Reset) RESET must be toggled from LOW-HIGH-LOW before sending a measurement command. RESET is usually LOW. 4.3.7 VDD (DC Voltage Input) It is recommended the user supply 3.0 VDC on this line, in part because the bias resistor values on the MicroMag module were optimized for 3.0 VDC operation.
4.3.10 VSTBY VSTBY is only available on the MicroMag2. (It is wired to VDD on the MicroMag2-on-Carrier and the MicroMag3.) VSTBY provides power to the SPI ports on the PNI ASIC. It should be tied to VDD to prevent current sinking which could be caused when another device is using the SPI bus.
5 Operation A single 8-bit command from the host system configures and initiates a sensor measurement. Only one sensor can be measured at a time. Each magneto-inductive sensor operates in an individual oscillator circuit composed of an external bias resistor along with digital gates and a comparator internal to the PNI ASIC. (See Figure 4-1.) To make a sensor measurement, a command byte is sent to the MicroMag through the SPI port specifying the sensor (axis) to be measured and the “Period Select”.
Figure 5-1: SPI Port Full Timing Sequence When implementing an SPI port, whether it is a dedicated hardware peripheral port or a software implemented port using general purpose I/O (also known as bit-banging) the timing parameters given in Figure 5-2 must be met to ensure reliable communications. Data is always considered valid while SCLK is HIGH (tDASH = Time, Data After SCLK High). When SCLK is LOW, data is in transition (tDBSH = Time, Data Before SCLK High).
5.2 Command Byte The operation of the MicroMag is controlled by the data received into the SPI port on the command byte. The command byte syntax is as follows: Table 5-1: Command Byte Position 7 6 5 4 3 2 1 0 BIT Name DHST PS2 PS1 PS0 ODIR MOT AS1 AS0 0 0 0 0 0 0 0 0 RESET 5.2.
Table 5-3: Period Select Period Select PS2 PS1 PS0 32 0 0 0 64 0 0 1 128 0 1 0 256 0 1 1 512 1 0 0 1024 1 0 1 2048 1 1 0 4096 1 1 1 5.2.3 Magnetic Oscillator Test (MOT) When set HIGH, MOT causes the magnetic oscillator circuit (selected by AS0 and AS1 in the directions selected by ODIR) to run continuously until the MicroMag is RESET. 5.2.4 Oscillator Direction (ODIR) ODIR determines the magnetic oscillator direction if MOT is set to 1.
5.4 Making a Measurement To make a sensor measurement, a command byte is sent to the MicroMag through the SPI port specifying the sensor (axis) to be measured and the “Period Select”. The Period Select defines the number of oscillation cycles (periods) to be measured in both the forward and reverse bias directions.
