MEMS and sensors

Posted on October 26, 2013 at 09:15There are no figures for clock stability over time and temperature. These are going to effect the sample rate times. For example, if the accelerometer DOR is 100Hz, what spread can be expected. I take it that in all of the three sensors types, that the time from commencing a conversion to the Interrupt, the time is roughly the reciprocal of the DOR. Is this true for the Magnetometer, where I assume the Set/Reset takes a fixed time during every sample, irrespective of the DOR. I am wanting to have a fixed data update rate of 100Hz, generated from the host processor, has anyone done this sort of thing, or are you just free running the LSM9DS0, and accepting the rate programmed into it? I accept that I will only get an effective 50Hz from the magnetometer at the rate I require. I am new to this device, have used analogue parts previously, where I could get better control of the sampling rate.Any comments would b

Posted on February 20, 2014 at 08:31I connected LIS3DH in the following way , but the device does'nt give the correct reading.          What is wrong with this configuration? Vin = 3.3V, SPI 4 wires. I configured the registers with the following string  at SPI: 0x60,0x77,0,0x10,0xC8,0,0 (command 0x60 , Reg1 0x77, Reg2 0, reg3 0x10, reg 4 0xC8, reg 5 & 6 0.) I can read this conficuration back and it's stored OK at the device. I read data by command 0xE8+6 bytes of zero But the OUT_XY&Z give me wrong values .  Eg 0xFE,0xA0,0x01,0xA0,0xFD,0x70 0r 0xFE,0x90,0x01,0x90,0xFD,0x40

Posted on January 27, 2014 at 07:06Hello, what is the difference between these two modules? Why DLC is so much expensive? #lsm330 #lsm330 #lsm330dlc

Posted on February 23, 2014 at 06:04The description page of the L3G4200D gyroscope says that it is an angular rate sensor able to provide unprecedented stablility of zero rate level and sensitivity over temperature and time. Does that mean that there is no need to fuse it with an accelerometer for calculating angle? #l3g4200d-gyroscope

Posted on February 12, 2014 at 17:44HelloI am trying to use the LIS3DH in FIFO Mode with Filter enabled.In this mode, the X-Axis, and Y-Axis values get some normal values (they oscillate between -10 and +10) but the Z-Axis value seems to have a bypass to the filter mode, the Z-Axis gives for example -616 witch is not the value for Z-Axis if i disable FIFO and Filter.Is this some kind of limitation of LIS3DH? or am i making something wrong at initialization.In my initialization code the registers are initialized with the following values:CTRL_REG1 = 0x17CTRL_REG2 = 0x88CTRL_REG3 = 0x00CTRL_REG4 = 0x40CTRL_REG5 = 0x40CTRL_REG6 = 0x00FIFO_CTRL_REG = 0x40Thank YouArtur Vieira

Posted on December 16, 2013 at 14:53In LIS3DH datasheet (Doc ID 17530) on table 25 we can see: Default value 00     ODR3-0 (0000:50Hz Others:...) on table 26 we can see: 0000 Power down mode So what is ODR = 0000  Power down or 50Hz? #lis3dh

Posted on February 19, 2014 at 07:36Since there is a hole in the top of the LPS331APTR package, are special precautions needed during the assembly process? Is it OK to wash the boards?

Posted on February 18, 2014 at 16:40Not sure if this is the correct place to post this, but here we go.  I'm considering using a pressure sensor to prototype a method for fuel level sensing.  The sensor would be at the closed end of a straight tube at the top of a fuel tank.  The open end of the tube would be positioned near the bottom of the fuel tank.  As the fuel rises, the air pressure inside the tube would increase.  Then we can relate air pressure to fuel level.This could be a great solution as we would be isolating the sensor from the fuel.  However, I worry about how fuel vapors could affect the sensor over time.  Could anyone give me a detailed understanding of how this sensor is constructed?  Is there any inherent protection against certain elements?  Could anyone make a comment as to how they think this sensor would hold up to fuel vapors?  Thanks! #lps331ap-pressure-se

Posted on February 18, 2014 at 15:53Does anybody know if it possible to configure the LIS3DSH to apply a high-pass to the data output? #lis3dsh #high-pass

Posted on February 12, 2014 at 16:18What is the RF immunity of the ST MEMS microphones? How does the plastic package reject the radiated disturbances?

Posted on February 13, 2014 at 05:13Hi, i have a problem with LSM330dlc. Sometimes the gyroscope doesn't work fine. The gyroscope sends measures constants and then I should to disconnect the sensor of VCC (reset).After, in most cases it works well.With the accelerometer i don't have any problem.My code is (SPI communication):-------WriteSpiGiro(0x20,0xFF);     // CTRL_REG1_G. Power ON: 760Hz; Cut-Off: 100Hz; X,y,Z axis: OnWriteSpiGiro(0x21,0x20);  WriteSpiGiro(0x23,0x10);-------the other register are by default.is this particular sensor my problem? has this problem happened to someone else? thanks #lsm330dlc #gyroscopes

Posted on February 12, 2014 at 10:54I done I2c Communication with the LSM303DLM Module and am setting the normal power mode and ODR@50HZ and enabling xyz axises of Accelerometer and magnetometer and am reading the accelerometer and magnetometer readings but am getting 0's and 1's.How did aget data when sensor is in motion and changing directions.  The following is the code i written to access the LSM registers. Please any one help me to get dynamic data from the sensor. #define LSM_SDA PIN_C4 #define LSM_SCL PIN_C3 #use i2c(I2C2) int8 memxl,memxh,memyl,memyh,memzl,memzh,mxh,mxl,myh,myl,mzh,mzl; typedef short int i16_t;   i16_t AXIS_X;   i16_t AXIS_Y;   i16_t AXIS_Z;   i16_t M_AXIS_X;   i16_t M_AXIS_Y;   i16_t M_AXIS_Z;   void LSM_INIT() {      i2c_start

Posted on February 11, 2014 at 22:11 Hi all,I'm trying to read data from a L3G4200D gyro through an SPI module of aPIC32MX460F.The following is the code I'm using: void Spi1STL3G4200DConfig( void ) { unsigned int configA, configB; int rData; configA = SPI_MODE8_ON | SPI_CKE_ON | CLK_POL_ACTIVE_HIGH | MASTER_ENABLE_ON | SEC_PRESCAL_3_1 | PRI_PRESCAL_4_1; // 80/12 = 6.66Mhz configB = SPI_ENABLE; rData = SPI1BUF; IFS0CLR = 0x03800000; SPI1STATCLR = 0x40; OpenSPI1(configA, configB); //configuro i pin SPI1 mPORTDSetPinsDigitalOut(BIT_0 | BIT_9 | BIT_10); mPORTCSetPinsDigitalIn(BIT_4); //C4 input digitale if (STL3G4200D_SpiReadRegister(WHO_AM_I) != 0xD3) // ALWAYS OK ! return -1; DelayMs(200);

Posted on February 11, 2014 at 15:29I can't find where to set Big/Little endian data output in LSM9DS0. It (BLE) is in register 0x23 in LSM303DLHC.  Can anyone give me a help please? Thank you very much for your kindly help.  #lsm9ds0

Posted on November 22, 2013 at 14:19Hi everybody,I am trying my first steps with the A3G4250D MEMS Gyroscope. Unfortunately, I did not manage to get useful measurement information yet. What I want to do is the following: sample the angular rate with a ODR of 100 Hz read out the data from the FIFO every 250 ms read out the temperature register to implement temperature correction laterThis is how I set the configuration registers: CTRL_REG1: 0x0FCTRL_REG2: 0x00CTRL_REG3: 0x00CTRL_REG4: 0x00CTRL_REG5: 0x40FIFO_CTRL_REG: 0x39I have the following questions: Is there any conversion formula provided for the data in the OUT_TEMP register? Is my configuration correct to read out the measurements (ODR of 100 Hz) from the FIFO every 250 ms?

Posted on February 07, 2014 at 10:09Which is the correct way to interface a digital microphone to a codec?

Posted on February 04, 2014 at 16:57What is the clock frequency where the mics switch from normal mode to sleep mode?

Posted on July 19, 2012 at 09:48 I have STM32-P103 board which uses STM32F103RB micro. I connected I2C sensors to I2C2 pins as shown below : I use only 4 pins of the sensor, SCL, SDA, Vcc, GND.I have the following Initialization code & reading code: #define MPU6050_I2C I2C2 #define MPU6050_I2C_RCC_Periph RCC_APB1Periph_I2C2 #define MPU6050_I2C_Port GPIOB #define MPU6050_I2C_SCL_Pin GPIO_Pin_10 #define MPU6050_I2C_SDA_Pin GPIO_Pin_11 #define MPU6050_I2C_RCC_Port RCC_APB2Periph_GPIOB #define MPU6050_I2C_Speed 100000 void MPU6050_I2C_Init( void ) { I2C_InitTypeDef I2C_InitStructure; GPIO_InitTypeDef GPIO_InitStructure; /* Enable I2C and GPIO clocks */ RCC_APB1

Posted on February 06, 2014 at 09:59Hi, I'm testing L3GD20 with SPI on my small test board.  It looks like OK so I can get gyro data and DRDY signal with 760Hz. But when I monitor DRDY signal with my oscilloscope, it has a jitter sometimes.  The difference is about plus-minus 10-20 uSec.  It's not continuous jitter but 5 or 6 second each. I understand that L3GD20 has some time keeper to ADC the sensor with free running.  So I cannot modify the interval (760Hz), right ? Are there any issue to get no jitter with software or hardware ? Best Regards, Zak #l3gd20-drdy-stability

Posted on February 06, 2014 at 04:50Hi, I am evaluating the A3G4250D gyroscope, could any one give me formulae or steps to convert the gyro and temperature data into deg/sec, degC respectively. Regards, Kantha

Posted on January 10, 2014 at 20:15On power-up, does this gyroscope come up in operating, sleep, or power-down mode (i.e., when all SPI peripherals in my instrument are powered up by a common bus, how much is the gyro drawing?The datasheet says that Vdd may be disconnected (powering off measurement functions) but if Vdd-IO is maintained the (SPI) bus ''is not blocked.''  I assume this means that SDO and SDI are not pulled low by the powered-down gyro.  What is current drain from Vdd-IO when Vdd is off?I plan to use this gyro to measure slow (even < 1dps) rotation of an oceanographic drifter.  Can you reassure a mere biologist that this is an appropriate device?Thanks!Tom WolcottProfessor Emeritus #gyroscopes

Posted on December 04, 2013 at 10:11I'd like to evaluate the LSM9DS0 and LSM303C. I can't find any evaluation boards to order for these parts. Can you help me out?Thanks,Ian #lsm9ds0-lsm303c

Posted on October 12, 2013 at 08:27hi,guysI'm working on LSM9DS0 with STMEVAL-MKI109V2,using 4-wire SPI communication?read gyro's WAI reg is ok if keep CS_G=0 and CS_XM = 1 after EVAL board power on, but if CS_G=0 after CS_G=1 and CS_XM = 1,read WAI reg, MCU can't get any response(SDO=0xFF always),can anyone explain me why? I would be grateful if anyone could post LSM9DS0 SPI communication code.thanks. #lsm9ds0-4-wire-spi #psm9ds0-purchase

Posted on February 05, 2014 at 04:07 Hi,  Besides, about LPS25HTR, what are the Wake time from power down to �communication ready� and acquisition time in high resolution mode for this chip?  I think this chip is very good. Changhong #barometric-pressure-sensor

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