4 Degrees of Freedom MEMS Sensor Improvements

Transcription

1 4 Degrees of Freedom MEMS Sensor Improvements Design Document Name: Xin Zhou Yue Zhang Team Dec12-09 Ang Lv Nicholas Everett Jenn Grubb Advisor: Degang Chen Client: Bee Line Company Bob Last Updated: Dec 1 st 2012

2 Contents Contents... 1 Problem Statement... 4 Project Objectives... 4 System Block Diagram... 5 Voltage Regulator... 6 Inclinometer... 7 Gyro: Angular Rate Sensors... 8 Micro-Processor... 9 System Description Operating environment User interface description Functional Requirements Non-Functional Requirements Expected Deliverables Work Plan Work Breakdown Costs Project Schedule Risks

3 Detailed Design Microcontroller Inclinometer Gyro Interconnects Schematic Design Microcontroller and JTAG Gyro Schematic Design Inclinometers Schematic Design Regulators Schematic Design Testing Points on Schematic Layout Design Gyro Footprint Information Inclinometer Footprint Information Regulator Footprint Information Overview of Layout Final Product Test Plan Connectivity Test Ground level test

4 Regulators Voltage Test SPI Connection Test & Rough Board Function Test Appendix

5 Problem Statement The Beeline Company in Bettendorf produces equipment for performing wheel alignments on larger commercial vehicles. Currently, they bring the vehicle into a large bay and prepare to perform the alignment of the wheels. They use two different circuit boards connected to a computer to perform the alignment. The first circuit board contains a microprocessor (to process the information from the accelerometer and the gyro) and a 3-axis accelerometer (to ensure no movement is occurring). The second circuit contains a 1-axis gyro that can measure the angle of the wheel being aligned and is connected to the first board. The client has found that the circuit boards currently have a high failure rate. Many times during the alignment, the circuit board will stop responding or provide data that is out of the tolerance that is necessary. This requires the technicians to reinitialize the boards and begin the alignment again. Project Objectives Beeline has requested for the team to design a new circuit board for their alignment process to replace their current circuit boards. The team has the option of either placing all components on one circuit board or maintaining their current setup by using two circuit boards. The circuits need to be able to measure degrees of accuracy from an accelerometer or inclinometer and 0.1 degree or better for at least 2 minutes from the gyro. 4

6 System Block Diagram: Figure 1 System Block Diagram 5

7 Voltage Regulator Figure 2 Voltage Regulator The voltage regulator is designed for portable and wireless applications with demanding performance and space requirements. The voltage regulator is stable with a small 1uF ±30% ceramic or high-quality tantalum output capacitor. It is optimized for battery powered systems to deliver ultra-low noise, extremely low dropout voltage and low quiescent current. Key Specifications: 2.5 to 6.0V input range 150mA guaranteed output 50dB PSRR at VIN = VOUT + 0.2V 1.5μA quiescent current when shut down Fast Turn-On time: 200 μs 100mV maximum dropout with 150mA load 30μVrms output noise over 10Hz to 100kHz 40 to +125 C junction temperature range for operation 2.5V, 2.6V, 2.7V, 2.8V, 2.85V, 2.9V, 3.0V, 3.1V, 3.2V, 3.3V, 4.7V, 4.8V and 5.0V outputs standard There are two regulators currently used on the circuit board. One is 3.2V, and the other one is 4.7V. 6

8 Inclinometer The Inclinometer consists of two different sensing devices, one that measures angular changes about the X-axis and another for the Y-axis. The two signals are then used to calculate an angular displacement in one direction. Therefore, for our circuit, we will have to use two of these devices placed orthogonal to each other. Figure 3 Inclinometer Functional Diagram We will be using the SCA103t inclinometer from VTI technologies. The SCA103T Series is a 3D-MEMSbased single axis inclinometer family that uses the differential measurement principle. The high calibration accuracy combines extremely low temperature dependency, high resolution and low noise together with a robust sensing element design, to make the SCA103T an ideal choice for high accuracy leveling instruments. The VTI inclinometers are insensitive to vibration due to having over damped sensing elements plus they can withstand mechanical shocks of g. 7

9 Gyro: Angular Rate Sensors Gyros measure angular velocity, how fast something is spinning about an axis. Unlike inclinometers, gyros are not affected by gravity, so they make a great complement to each other. The angular velocity is in units of rotations per minute, or degrees per second. They can also tell you the amount of angular displacement from a specified position. We will be using the L3G4200D gyroscope from ST Microelectronics. Figure 4 Gyro Block Diagram 8

10 Micro-Processor A microprocessor incorporates the functions of a computer s central processing unit on a single integrated circuit. The microprocessor which is in this system collects analog data from data bus transceiver, and then it converts the analog data into digital signals for analyzing. It also receives 3 axis analog data from the accelerometer, and then converts from analog to digital. The microprocessor also controls some LEDs which represent different warnings. 9

11 System Description Operating environment The boards could possibly be used in a Thermotron oven that heats up the air from about 40 degrees Fahrenheit to around 100 degree Fahrenheit. Therefore, the components on the boards need to be able to withstand the temperature swing and still operate normally. User interface description Beeline interfaces with their current sensor boards with connections to the microprocessor through a JTAG port to an Olimex USB programmer. The two separate boards also interface with each other using a Board to Board RA header connection. Functional Requirements Inclinometers must be able to measure roll and pitch axis within degrees accuracy. Gyro needs to be able to measure a single axis (yaw) and have an accuracy of at least 0.1 degrees for at least 2 minutes. Circuit needs to have low power consumption since batteries will be used to power them. Circuit board must be able to function properly in a temperature range of degrees Fahrenheit. Circuit Board containing microprocessor must be able to connect to other equipment via SPI connection. 10

12 Non-Functional Requirements Circuit boards should be 1.6 inches by 1.15 inches in dimension. Circuits should be testable via test equipment supplied by Beeline Company. Expected Deliverables The final expected product will be a complete circuit board system capable of running on lithium ion batteries. The board will contain a microprocessor, an accelerometer sensor and a gyro sensor. It will connect to Beeline s current programming setup with JTAG connections. There will either be one complete board with both accelerometer and gyro sensors or two separate boards capable of connecting together. 11

13 Work Plan Work Breakdown The following are tasks that the team needs to accomplish over the two semesters to ensure a successful finished product. Project Definition Component Selection Circuit Design Initial Design Testing Finalized Design Board Design Board Fabrication Product Testing and Validation Final Documentation 12

14 Costs Material costs for the project have not yet been determined and will depend on the component selection. The client has requested that the total costs for new parts be less than $150. The following is a preliminary cost estimate. Item Notes Cost Microprocessor $3.50 Inclinometer Two are required $41.10 *2 = $82.20 Gyro $7.90 PCB Components PCB Fabrication Surface mount components, input/output jacks, battery enclosure, etc. Unknown as of 04/17/12 $40 (Estimated. Unknown as of 04/17/12) Enclosure Unknown as of 04/17/12 Total $

15 Project Schedule Project Definition Component Selection Initial Circuit Design Testing Final Circuit Design Board Design Board Fabrication Completed Remaining Product Testing Final Documentaion Risks The major risk that we will face is the possibility of destroying any of the sensors or the microprocessor as they would be expensive to replace. The team can take precautionary measures by thoroughly analyzing and simulating a circuit before starting any testing procedures. This will help by reducing the risk of the circuit failing and damaging any of the components. 14

16 Detailed Design Microcontroller We will be using the same microcontroller as the current board setup in order to reduce cost for our client. The microcontroller is a MSP430F247 from Texas Instruments, which has low power modes that benefit battery-operated devices such as ours. It features a 16-bit RISC CPU, 16-bit registers, 48 I/O pins, and has not been a cause of problems for our client with the current design. Inclinometer The board will use two inclinometers positioned in perpendicular angles to measure the amount that the device tilts. Once the board no longer detects a change in angle, it will output a reading. The device we chose to use was a SCA103T series MEMS single axis inclinometer that has high resolution and low noise which contributes to its high accuracy. The device has a 12 bit data output, a current consumption of 5mA and a supply voltage range of V. The noise for this inclinometer is around /, or 6.96, making this an acceptable component for our client s specifications. The device will communicate with the microcontroller via SPI communication procedures. 15

17 Gyro The gyro we will be using is the L3G4200D from STMicroelectronics. The L3G4200D is a low-power three-axis angular rate sensor able to provide unprecedented stability of zero rate level and sensitivity over temperature and time. It includes a sensing element and an IC interface capable of providing the measured angular rate through a digital interface (SPI). It is an ultra-stable three axis digital output gyroscope that has three selectable ranges (250/500/2000 /s) which has a 16 bit data output. Some other features are that it is very stable over a wide temperature and time range, has a low power consumption of 6.1 ma during operation, and a wide supply voltage range. We will only be using the yaw axis of the gyro to satisfy the client s requirements and this may save on power consumption since the other two axes will not be in use. Interconnects The board to board connections will be made by using a board to board header. This will allow the gyro board to interface with the microprocessor on the other circuit board. The microprocessor board will receive its power via a Molex connector. All other data with be transferred via SPI between components. 16

18 Schematic Design Microcontroller and JTAG Figure 5, MSP430 and JTAG Schematic view By following the description that given in MSP430 data sheet, it is decided to use two groups of capacitors to stabilize the voltage. Use a JTAG to build up interface between microcontroller and the computer, so that the microcontroller can be programmed. There are two groups of SPI, one is connecting to the main board, and the other on group are controlling two inclinometers and a gyro, program PIN SSEL0, SSEL1, SSEL2, so that we can choose which component that we are going to send or receive data. SCL0 is used to be clock signal, and MISO is called master input slave output which is used to receive data from sensors. MOSI is called master output slave input, which is used to send control signals to the sensors. 17

19 Gyro Schematic Design Figure 6 Gyro Shcematic View Power supply decoupling capacitors (100 nf ceramic or polyester +10 μf) should be placed as near as possible to the device (common design practice). If Vdd and Vdd_IO are not connected together, power supply decoupling capacitors (100 nf and 10 μf between Vdd and common ground, 100 nf between Figure 7 Gyro (Vdd Connection) Vdd_IO and common ground) should be placed as near as possible to the device (common design practice). The L3G4200D IC includes a PLL (phase locked loop) circuit to 18

20 synchronize driving and sensing interfaces. Capacitors and resistors must be added at the PLLFILT pin (as shown in Figure 8 PLL of gyro As using a group of capacitors to stabilize the gyro Vdd, then use a PLL circuit to drive and sense interfaces. Then used SPI connection MOSI0 and MISO0 to control it, use SCK0 to clock it, and SSEL0 to select gyro when we want its data send off to microcontroller. Inclinometers Schematic Design Figure 9 Two Inclinometers 19

21 Figure 10 Inclinometer Connection Example As the example found from data sheet above, the inclinometer need a Vdd power which is about 5V, and then need connect a 100n capacitor to it. It also needs one SPI control since we only need its digital data. MOSI0 and MISO0 used as SPI, SCK0 used as clock, and SSEL1 and SSEL2 to select two inclinometers when we want its data send off to microcontroller. Regulators Schematic Design Figure 11 Two Regulators 20

22 The decision of the values of the regulators are made due to the power requirement of gyro and inclinometers. The gyro need typical Vdd of 3V and inclinometer need 5V, so we use 3V and 5V regulators. As left figure 12 shown, it requires 3 capacitors, two of them are 1 uf, and another one with star is called optional noise capacitor, which can be 1 uf too. Figure 12 Regulator Connection Testing Points on Schematic Figure 13 Testing Points Schematic View Since all of our components send off digital signal, we do not need to have a lot of testing points for our schematic design. For users more convenient, we still add five testing PINs to make sure everything is working fine on the sensor board. There are two voltage needed to be checked since they are produced by regulators, and then it will be the SPI connections, in order to check if it has a good SPI connection. 21

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24 Layout Design For the layout part, some components that we have to create our own library of footprint since it is not possible to find one online. There is no worry to build the layout of microcontroller, because most of the software have the library layout for TI s MSP430. We do need to build our own footprint of gyro, inclinometers and regulators. Gyro Footprint Information 23

25 Inclinometer Footprint Information Figure 14 Footprint of Inclinometer size in (mm) Regulator Footprint Information Figure 15 Regulator Footprintin inches or (mm) 24

26 Overview of Layout Figure 16 Layout Overview There are total 2 layers for this sensor board, and every component is fit on the top board. 25

27 Final Product Figure 17 Manufactured Sensor Board 26

28 Test Plan Testing list: 1. Connections test 2. Ground level test 3. Regulators voltage test 4. SPI connection test & Rough function test 1)Connectivity Test The purpose of this test is to ensure that all the connections are correct on the circuit board prior to connecting any components or applying power. Required Items: Ohmmeter x 1 Connection leads x 2 People Required: Technician x 2 Instructions: This test will require two people (person A and person B). Person A will read a connection that should be checked while person B will use the ohmmeter to verify the connection. If a connection is made, the ohmmeter should indicate that by being very close to 0 ohms. If it is open, the ohmmeter will not be close to 0. All of the connections below should be near 0 ohms when checked. In the event one of the connections is not near 0 ohms, Person B should check to see whether either or both of those pins are connecting to any other connection. Example of Bad Connection: If Microcontroller pin 5 to Gyro pin 1 is reading 5M ohms, then person B should check Microcontroller pin 5 to every other pin on the board to ensure that it is not wired to the incorrect place. Person B should also do the same for Gyro pin 1. If any connections from either of those pins are found, consult the schematic to verify whether that connection should be there. If there is a connection made that should not be there, the board may be inoperable and should not have any components placed on the board. The entire team should also be notified if a bad connection is found. Other Information: Below are the pin outs of the microcontroller, gyro, and inclinometers. After a connection is verified, a check mark should be placed next to it by person A. Always consult the schematic if needed. 27

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31 List of Connections to be Verified Microcontroller pins 1 to 3V in 8 to Micro pin 1 28 to J2 pin 3 29 to J2 pin 2 30 to J2 pin 6 31 to J2 pin 4 32 to U4 (Inclin 2) pin 7 44 to U3 (Inclin1) pin 7 45 to U3 (Inclin1) pin 4 45 to U4 (Inclin 2) pin 4 45 to U2 (Gyro) pin 3 46 to U3 (Inclin1) pin 3 46 to U4 (Inclin2) pin 3 46 to U2 (Gyro) pin 4 47 to U3 (Inclin1) pin 1 47 to U4 (Inclin2) pin1 47 to U2 (Gyro) pin 2 48 to U2 (Gyro) pin 5 53 to Ground 53 to JTAG pin 1 53 to JTAG pin 8 54 to JTAG pin 2 55 to JTAG pin 3 56 to JTAG pin 4 57 to JTAG pin 5 62 to Ground 63 to Ground 64 to L1 (Inductor) Checked Good Checked Bad 30

32 Gyro Pins 14 to C9 (Capacitor) 14 to C10 (Capacitor) 8 to Ground 9 to Ground 10 to Ground 11 to Ground 12 to Ground 13 to Ground 1 to 3V in 15 to Gyro pin 1 16 to Gyro pin 1 1 to C7 1 to C8 Checked Good Checked Bad Inclinometer 1 pins 6 to Ground 12 to C5 12 to 5V in Checked Good Checked Bad Inclinometer 2 pins 6 to Ground 12 to C6 12 to 5V in Checked Good Checked Bad U5 pins 1 to J2 pin 7 3 to U5 pin 1 2 to C14 2 to C15 2 to C16 4 to C15 5 to C16 5 to 3V in Checked Good Checked Bad 31

33 U6 pins 1 to U6 pin 3 1 to J2 Pin 7 1 to C11 2 to Ground 2 to C14 2 to C15 2 to C16 4 to C15 5 to C16 5 to 3V in Checked Good Checked Bad Other Pins C1 to Ground C1 to 3V in C2 to Ground C2 to 3V in C3 to Ground C3 to L1 C4 to Ground C4 to L1 C9 to R1 C10 to Ground R1 to Ground C5 to Ground C6 to Ground C7 to Ground C8 to Ground C14 to J2 pin 7 C11 to J2 pin 7 L1 to 3V in JTAG pin 6 to 3V in JTAG pin 7 to J2 pin 5 Checked Good Checked Bad 32

34 2) Ground level test Check all of the PINs of every component which are grounded, make sure that all the GND PINs are really close or equals 0 while giving a voltage supply. Required Items: 1. Power Supply 2. Banana to Alligator x 2 3. Connection leads x 2 4. DMM (Digit Multimeter) People Required: Technician x 2 Instructions: Step 1, Person A control power supply, and adjust the voltage to 5V, then use one banana to Alligator connect to PIN VDD at Board Header, and then use the other one connect to G0. PIN G0 to G13 are shown in picture below. Step 2, Person A turns on power supply. Person B use two connection leads connect to DMM to measure DC voltage, and then connect the leads to the PCB at desired PINs from G1 to G13. At the same time person A read from DMM, and check if values are equal to 0, and use pen to check on verification sheet. If failure and non-zero values show up, we have to recheck the connection between power supply and board header, check if G0 equals to 0. Then again measure the failed ground PIN. If it still fails, we have to solder and fix it. 33

35 Ground Level Verification Sheet Measure the voltage between G1 ~ G13 and G0, G0 and COM of power supply. PIN name Voltage value Verify G0 ~ COM G1 G2 G3 G4 G5 G6 G7 G8 G9 G10 G11 G12 G13 34

36 3) Regulators Voltage Test Assume to get voltage 5V from main board, and it is battery based. We need to supply a 5V of voltage to see if we can get a constant voltage output from regulators. Required Items: 1. Power Supply 2. Banana to Alligator x 2 3. Connection leads x 2 4. DMM (Digit Multimeter) People Required: Technician x 2 Instructions: Step 1, Person A control power supply, and adjust the voltage to 5V, then use one banana to Alligator connect to PIN VDD at Board Header, and then use the other one connect to G0. PIN G0 to G13 are shown in picture below. Step 2, Person A turn on power supply. Person B use connection leads the same as in part 2), but except measure the R1 and R2 on board, at the same time, Person A record voltage value while person B measure the voltage of two regulators, and we also need measure the voltage which were sent out to gyro and inclinometers. 35

37 Voltage Regulators Verification Sheet Measure the voltage from PINs to GND, and record in the sheet below. PIN name GND V_desired (V) V_measured (V) R1 G11 +3 Verify R2 G12 +5 A1 G7 +5 A2 G9 +5 Gy G5 +3 Gy G4 +3 M G1 +3 M G2 +3 M G3 +3 J G13 +3 Reference: R: Regulators A: Inclinometers Gy: Gyro M: Microcontroller J: JTAG G: Ground 36

38 4) SPI Connection Test & Rough Board Function Test This test is to verify if we have a good connection of SPI, Required Items: 1. Power Supply 2. Banana to Alligator x 2 3. JTAG Cable to PC 4. Oscilloscope BNC Connector People Required: Technician x 2 Instructions: Step 1, Person A control power supply, and adjust the voltage to 5V, then use one banana to Alligator connect to PIN VDD at Board Header, and then use the other one connect to G0. PIN G0 to G13 are shown in picture below. Person B sets up computer, and connect JTAG cable to PC, get program ready. Person A set up oscilloscope. Step 2, Person A turn on power supply, and observe signals. Person B use BNC connector to connect between circuit board and oscilloscope. First connect to MOSI and MISO, person A control PC and program. Person B and observe signals, and take picture of it. Step 3, Person A keep control PC and program, Person B change BNC connector to SEL and CLK PINs, observe signals on oscilloscope. Step 4, Move around circuit board and then observe if signals at MISO are changed. Connection Specification: S*: Select C: Clock Pin: SPI receiving data 37

39 Pout: SPI send command PIN connection S0 to G3 Verify S1 to G3 S2 to G3 C to G3 Pin to G3 Pout to G3 Take Pictures just in case if we need to analyze it again in the future. 38

40 Use software to modulate SPI signals, and plot outputs of MISO0, MOSI0, SSEL0. Modulate signals sending out from microprocessor to inclinometers and gyro, connect MOSI0 to Terminal 1 of Oscilloscope, and observe the input signals on Terminal 1. Connect MISO0 to Terminal 2 to observe signals which are coming from inclinometers and gyro. Compare the signals observed from scope and modulation plots to ensure they are correct according to datasheets. Figure 18, Example As clock is set to be at frequency T, the signals should be the same in each selected period T, since the sensor is set at flat plane and not moving. 39

41 Appendix Code: /* * main.c */ #include <msp430x24x.h> #include <math.h> #define pi #define uint unsigned int //// #define uchar unsigned char //// #define CTRL_REG1 0x20 // #define CTRL_REG2 0x21 // #define CTRL_REG4 0x23 #define REFERENCE 0x25 #define out_temp 0x26 #define STATUS_REG 0x27 #define OUT_X_L 0x28 #define OUT_X_H 0x29 #define OUT_Y_L 0x2A #define OUT_Y_H 0x2B #define OUT_Z_L 0x2C #define OUT_Z_H 0x2D #define reset_cs P5DIR&=~BIT4; //assign P5^4 = 0; #define set_cs P5DIR =BIT4; //assign P5^4 = 1; #define reset_clk P5DIR&=~BIT3; //P5^3 = 0; #define set_clk P5DIR =BIT3; //P5^3 = 1; #define reset_sdi P5DIR&=~BIT2; //P5^2 = 0; #define set_sdi P5DIR =BIT2; //P5^2 = 1; #define reset_sdo P5DIR&=~BIT1; //P5^1 = 0; #define set_sdo P5DIR =BIT1; //P5^1 = 1; typedef unsigned char BYTE; unsigned char incl_one_outdata; ///< SPI master to slave(inclinometer 1) data unsigned int incl_one_x_data = 0; ///< SPI slave(inclinometer 1) to master data unsigned int incl_one_y_data = 0; unsigned char incl_two_outdata; ///< SPI master to slave(inclinometer 2) data unsigned int incl_two_x_data = 0; ///< SPI slave(inclinometer 2) to master data unsigned int incl_two_y_data = 0; unsigned char incl_read_x = 0x10; // < SPI command to read X data unsigned char incl_read_y = 0x11; ///< SPI command to read Y data volatile unsigned int gyro_outdata; ///< SPI master to slave(gyro) data unsigned int gyro_indata; ///< SPI slave(gyro) to master data volatile unsigned int gyro_offset = 0; //holds the value for the offset 40

42 of the gyro unsigned int tempdata; int diff_1 = 0; inclinometer 1 int diff_2 = 0; inclinometer 2 //volatile double angle_1; of inclinometer 1 //volatile double angle_2; of inclinometer 2 volatile double angle; //holds difference value for //holds difference value for //holds value for the angle //holds value for the angle volatile union int ang_1[4]; float angle_1; val_to_send_1; volatile union int ang_2[4]; float angle_2; val_to_send_2; //initialize input and output pins *********not needed******** //delay void delay (int n) int i =0; for (i = 0; i<n; i++) // _nop_(); ///one clock cycle? //initialize master clock to 8MHz void initclk(void) int i = 0; WDTCTL = WDTPW + WDTHOLD; timer // Stop watch dog if (CALBC1_8MHZ == 0xFF CALDCO_8MHZ == 0xFF) // Clock to 8Mhz while(1); calibration constants erased do not load, trap CPU!! // If BCSCTL1 = CALBC1_8MHZ; to 8MHz DCOCTL = CALDCO_8MHZ; 8MHz for(i=16800;i>0;i--); stabilize. // Set Basic Clock // Set DCO to // Wait for DCO to 41

43 //initialize SPI bus as 3 wire master to gyro/inclinometer1/inclinometer2 void initspi(void) //SPI to gyro and inclinometers P3DIR = 0x10; // set p3.4 to output for inclinometer 2 select P3OUT = 0x10; // set slave reset high - p3.4 P5DIR = 0x11; // set P5.0,4 to output for inclinometer 1 select and gyro select P5OUT = 0x11; // Set slave reset high - P5.0,4 P5SEL = 0x0E; // P5.1,2,3 USCI_B1 option select UCB1CTL0 = UCCKPH + UCMST + UCSYNC + UCMSB; // 3-pin, 8-bit SPI master MSB First UCB1CTL1 = UCSSEL_2 + UCSWRST; // SMCLK for BRCLK UCB1BR0 = 0x10; // SPICLK = SMCLK / 16 = 0.5MHz Spi Clock ---- Max allowed for Inclinometers UCB1BR1 = 0; UCB1CTL1 &= ~UCSWRST; // SPI enable delay(50); //set all unused pins to output and output low to avoid interference void init_unused_pins() P1DIR = 0xFF; P1OUT = 0x00; P2DIR = 0xFF; P2OUT = 0x00; P3DIR = 0xE0; P3OUT = 0x1F; P4DIR = 0xFF; P4OUT = 0x00; P5DIR = 0xE0; P5OUT = 0x1F; P6DIR = 0XFF; P6OUT = 0X00; //! initializes SPI bus as 3 wire slave to ARM void initarmspi(void) //Spi to ARM P3DIR =0x01; select P3SEL = 0x0E; option select UCB0CTL0 = UCSYNC + UCMSB; MSB First UCB0CTL1 &= ~UCSWRST; UC0IE = UCB0RXIE; // Set P3.0 to input for SPI slave // P3.1,2,3 SPI USCI_B0 // 3-pin, 8-bit SPI slave // SPI enable // Enable USCI RX interrupt //Gyro write 42

44 void GyroWrite (uchar address, uchar write) uchar i; set_cs; delay(50); reset_cs; //pull down the CS signal delay(30); address = address & 0x3f; for (i=0; i<8; i++) if ((address&0x80) == 0x80) set_sdi; else reset_sdi; delay(20); reset_clk; delay(20); set_clk; delay(20); address = address <<1; for (i=0; i<8; i++) if ((write & 0x80) == 0x80) set_sdi; else reset_sdi; delay(20); reset_clk; delay(20); set_clk; delay(20); //read address bit by bit //write address bit by bit write = write <<1; delay(40); set_cs; //Gyro Read uint GyroRead (uchar address) uchar i; uint ReadData; set_cs; delay(50); reset_cs; 43

45 set_clk; delay(20); address = address & 0x3f; address = address 0xc0; for (i = 0;i<8;i++) if ((address&0x80) == 0x80) set_sdi; else reset_sdi; delay(20); reset_clk; delay(20); set_clk; delay(20); address = address <<1; //P5^1 = 0; ReadData = 0; for (i=0;i<16;i++) reset_sdi; delay(20); reset_clk; delay(20); set_clk; delay(20); if (P5DIR 0x02 == 0x02) ReadData = 0x0001; else ReadData &= 0xfffe; if (i<15) ReadData = (ReadData <<1)& 0xfffe; delay(20); //#define reset_sdo P5DIR&=~BIT1; delay(50); set_cs; return ReadData; //initialize gyro void GyroInit(void) GyroWrite(CTRL_REG1, 0x8f); //sets ODR to 400 Hz and BW to 00 for cutoff of 20 44

46 //initialize inclinometer 1 *******not needed******** //initialize inclinometer 2 *******not needed******** //get gyro data uint GyroDataZ(void) uint dataz; dataz = GyroRead(OUT_Z_L); return dataz; //get inclinometer 1 data float getincl_one_data() int i = 0; angle = 0; //read in the X data P5OUT &= ~0x01; for(i = 0; i < 5; i++); clk while (!(IFG2 & UCB1TXIFG)); UCB1TXBUF = incl_read_x; // Spi Select low // delay between select and SPI // USCI_B1 TX buffer ready? while (!(IFG2 & UCB1RXIFG)); // USCI_B1 RX buffer ready? incl_one_x_data = UCB1RXBUF; // Receive first 8 bits incl_one_x_data = incl_one_x_data << 8; //shift first 8 to make room for next 8 while (!(IFG2 & UCB1RXIFG)); tempdata = UCB1RXBUF; incl_one_x_data = incl_one_x_data tempdata; incl_one_x_data = incl_one_x_data >> 5; need 11 bits P5OUT = 0x01; // USCI_B1 RX buffer ready? // receive next 8 bits //combine 16 bits together //toss out lowest 5 since only // Spi Select high select clk for(i = 0; i < 5; i++); //read in the Y data P5OUT &= ~0x01; for(i = 0; i < 5; i++); // delay between deselect and // Spi Select low // delay between select and SPI 45

47 /* for(i = 0; i < 19; i++) incl_one_y_data = incl_one_y_data << 1; for next one while (!(IFG2 & UCB1TXIFG)); UCB1TXBUF = incl_read_y; while (!(IFG2 & UCB1RXIFG)); incl_one_y_data = UCB1RXBUF; //shift first bit to make room // USCI_B1 TX buffer ready? // USCI_B1 RX buffer ready? // Receive bit incl_read_y = incl_read_y >> 1; position */ while (!(IFG2 & UCB1TXIFG)); UCB1TXBUF = incl_read_y; //shift next bit to be sent into // USCI_B1 TX buffer ready? while (!(IFG2 & UCB1RXIFG)); // USCI_B1 RX buffer ready? incl_one_y_data = UCB1RXBUF; // Receive first 8 bits incl_one_y_data = incl_one_y_data << 8; //shift first 8 to make room for next 8 while (!(IFG2 & UCB1RXIFG)); tempdata = UCB1RXBUF; incl_one_y_data = incl_one_y_data tempdata; incl_one_y_data = incl_one_y_data >> 5; need 11 bits // USCI_B1 RX buffer ready? // receive next 8 bits //combine 16 bits together //toss out lowest 5 since only P5OUT = 0x01; // Spi Select high //calculate angle diff_1 = incl_one_x_data - incl_one_y_data; and Y values angle = asin(((double)diff_1)/6554) *180/pi; for inclinometer //find difference between X //calculate angle return (float)angle; //get inclinometer 2 data float getincl_two_data() int i = 0; angle = 0; //read in the X data P3OUT &= ~0x10; for(i = 0; i < 5; i++); clk *******not yet completed******* // Spi Select low // delay between select and SPI while (!(IFG2 & UCB1TXIFG)); UCB1TXBUF = incl_read_x; // USCI_B1 TX buffer ready? while (!(IFG2 & UCB1RXIFG)); // USCI_B1 RX buffer ready? incl_two_x_data = UCB1RXBUF; // Receive first 8 bits incl_two_x_data = incl_two_x_data << 8; //shift first 8 to make room for next 8 46

48 while (!(IFG2 & UCB1RXIFG)); // USCI_B1 RX buffer ready? tempdata = UCB1RXBUF; // receive next 8 bits incl_two_x_data = incl_two_x_data tempdata; //combine 16 bits together incl_two_x_data = incl_two_x_data >> 5; //toss out lowest 5 since only need 11 bits select clk P3OUT = 0x10; for(i = 0; i < 5; i++); //read in the Y data P3OUT &= ~0x10; for(i = 0; i < 5; i++); // Spi Select high // delay between deselect and // Spi Select low // delay between select and SPI while (!(IFG2 & UCB1TXIFG)); UCB1TXBUF = incl_read_y; // USCI_B1 TX buffer ready? while (!(IFG2 & UCB1RXIFG)); // USCI_B1 RX buffer ready? incl_two_y_data = UCB1RXBUF; incl_two_y_data = incl_two_y_data << 8; //shift first 8 to make room for next 8 while (!(IFG2 & UCB1RXIFG)); // USCI_B1 RX buffer ready? tempdata = UCB1RXBUF; // receive next 8 bits incl_two_y_data = incl_two_y_data tempdata; //combine 16 bits together incl_two_y_data = incl_two_y_data >> 5; //toss out lowest 5 since only need 11 bits P3OUT = 0x10; // Spi Select high //calculate angle diff_2 = incl_two_x_data - incl_two_y_data; difference between X and Y values angle = asin(((double)diff_2)/6554) *180/pi; for inclinometer //find //calculate angle return (float)angle; //send data to ARM *******not yet completed******* void send_data() int i = 0; //send out angle 1 for(i = 0; i < 4; i++) 47

49 while (!(IFG1 & UCB0TXIFG)); // USCI_B0 TX buffer ready? UCB0TXBUF = val_to_send_1.ang_1[i]; //send upper portion of angle 1 and shift up accordingly /* while (!(IFG1 & UCB0TXIFG)); // USCI_B0 TX buffer ready? UCB0TXBUF = angle_1; //send upper portion of angle 1 and shift up accordingly angle_1 = angle_1 << 8; while (!(IFG1 & UCB0TXIFG)); // USCI_B0 TX buffer ready? UCB0TXBUF = angle_1; //send upper portion of angle 1 and shift up accordingly angle_1 = angle_1 << 8; while (!(IFG1 & UCB0TXIFG)); // USCI_B0 TX buffer ready? UCB0TXBUF = angle_1; //send upper portion of angle 1 and shift up accordingly angle_1 = angle_1 << 8; while (!(IFG1 & UCB0TXIFG)); // USCI_B0 TX buffer ready? UCB0TXBUF = angle_1; //send upper portion of angle 1 and shift up accordingly angle_1 = angle_1 << 8; */ //send out angle 2 for (i = 0; i < 4; i++) while (!(IFG1 & UCB0TXIFG)); UCB0TXBUF = val_to_send_2.ang_2[i]; of angle 1 and shift up accordingly // USCI_B0 TX buffer ready? //send upper portion //send out gyro data for (i = 0; i < 2; i++) while (!(IFG1 & UCB0TXIFG)); UCB0TXBUF = gyro_outdata << (8*i); gyro data and shift up accordingly // USCI_B0 TX buffer ready? //send upper portion of //Calculate the offset of the gyro when it is first turned on unsigned int calc_offset() unsigned int temp = 0; int i; for (i = 0; i < 50; i++) temp += GyroDataZ(); temp = temp / 50; return temp; //averages the gyro data to get a more reliable reading unsigned int avg_gyro() unsigned int temp = 0; 48

50 int i; for (i = 0; i < 25; i++) temp += GyroDataZ(); temp = temp / 25; return temp; void main() int i = 0; unsigned int temp2 = 0; initclk(); initspi(); initarmspi(); GyroInit(); gyro_offset = calc_offset(); for(i = 0; i<50;i++); while(1) val_to_send_1.angle_1 = getincl_one_data(); val_to_send_2.angle_2 = getincl_two_data(); //need loop to average gyro readings //then gyro angle = gyro angle + h ( for 400 Hz) * R (Raw data in LSB's from gyro after corrected for offset and threshold) * Scale Factor for axis (only needed for super high accuracy) temp2 = avg_gyro(); gyro_outdata = gyro_outdata * (temp2 - gyro_offset); send_data(); 49