MEMS (sensors)

Posted on December 19, 2013 at 17:28In LIS3DH datasheet (Doc ID 17530) on figure 3 page 12/42 we can see: ''When no communication is on-going, data on CS, SPC, SDI and SDO are driven by internal pull-up resistors.'' What is the pull-up value? Are these pull-up still active if the LIS3DH is put in power down mode? #lis3dh-spi

Posted on June 13, 2017 at 06:03Hello:I am getting some bizarre values from this device, and maybe it's not configured correctly, or I am not reading it correctly.It appears I can send and read from the device. I can use the 'WHO_AM_I' and get back the value 32, which is correct. I then set the control register 1 at 0x20  to 0x27 = b00100111, which sets PM to normal, and x, y and z enabled. To check if the register has taken the value, I read it back, and it says 0x27.I'm assuming then that after doing this, I can just read the output registers at x,y and z, and  I am doing reads every 100ms (I do not have the interrupts configured at this point, and for now, not converting from two's complement)However, I am unable to get the output registers to change from 0xFF, no matter what I do with the board it's mounted on. I have tried some pretty hard 'nudges' and it will not change. Additionally, if I continuously read the

Posted on June 08, 2017 at 16:57Hi all,I am testing a LSM9DS1 module to replace a L3GD20. I get readouts for the gyro, the accellerometer and the magnetometer. However when I turn my pcb I can see value changes on the accellerometer and the magnetometer but the gyroscope signals (despite some noise) do not change. When I disable the individual gyroscope outputs then these go to 0 so I read the right registers. I also tried changing output rates, bandwidth and so on without success. I also tried the selftest, that doesn't change the gyro outputs either. Is my part broken?Thanks,André

Posted on June 12, 2017 at 20:42Hi,Some time ago I've succesfuly used lsm9ds0 (SparkFun) for 3D magnetic field readings. Today I'm trying to upgrade my device to use lis3mdl (MinIMU-9 v5 Gyro) but the magnetometer output is different than lsm and I don't know how to interpret it. It seems that X and Y axis woks simillar to lsm (positive and negative readings dependent on imu position) but the Z is always positive (eg 1500-4500 raw @ +/-4 gauss ) which I don't understand.I've used config from AN4602:M_CTRL_REG2,        0x40M_CTRL_REG1,        0xfcM_CTRL_REG4,        0x0cM_CTRL_REG3,        0x00I assumed that the magnetic field of measurement would be the same on lms9ds0 and lis3mdl but It seems that it's not or Am I doing something wrong?Thank you

Posted on June 06, 2017 at 09:20I am having some problems when I try to get data from my sensor. I can read registers and get some data but I don't know how I should do the covnersion to get a real value.I am using an arduino and I found some libraries. Those libraries tend to use this format: x = ((int8_t)sensorData[1])*256+sensorData[0]; y = ((int8_t)sensorData[3])*256+sensorData[2]; z = ((int8_t)sensorData[5])*256+sensorData[4];Where position 0 of sensorData starts at OUT_X_L (28h) and goes up.Is this right? I have read something about left justified of LSB and I think it should be like:Is it the same?Apart from that, they use a formula to get mg values from the x,y and z values:x = (int32_t)x*1000/(1024*mgScaleVel); //transform data to millig, for 2g scale axis*1000/(1024*16), y = (int32_t)y*1000/(1024*mgScaleVel); //for 4g scale axis*1000/(1024*8), z = (int32_t)

Posted on June 08, 2017 at 11:05Hello,I set the data rate (ODR) to 400Hz in high resolution mode with fifo stream mode enable of LIS2SH12.For 3 minutes measurement test, I excepted to receive 72000 (400 * 60 * 3) data for each axis, however I only received around 68220 number of data, which the data rate is around 379Hz (~5% tolerance).I also tested with two other LIS2DH12 samples, one is 378Hz, and the other one is 399Hz.Therefore I suppose the data rate has tolerance with it.Myy question are:1 Since the data sheet only provide the 'typical' value, any application note describe the tolerance of data rate?2 Is it possible to calibrate the data rate with register setting?Thank you very much.#lis2dh12 #odr #fifo #data-rate

Posted on June 12, 2017 at 01:32Dear sir/madam,I'm confused how can we change register concatenation data (eg. OUTX_H&OUT_L: FD5Ch) into a 10-bit data (eg. X: -676*0.061=-41mg)? Where -676 comes from and why this number is negtive?  [page 16 of AN4748 Application note]#lis2ds12-output-data

Posted on June 03, 2017 at 01:44In TN0018 'Surface mounting guidelines for MEMS sensors in an LGA package', on Page 5 it offers different guidance on land pad dimensions depending on whether the 'LGA pin spacing' is (a) greater than 0.2 mm or (b) equal to or less than 0.2 mm. If (a), it says oversize the land pads by 0.1 mm in both length and width; if (b), the land pads are not oversized.QUESTION 1: Does the phrase 'LGA pin spacing' mean open space between pins or pin pitch? I don't think I've seen a part with 0.2 mm pitch, to say nothing of less than that; the smallest microBGA parts I've seen have a pitch more than 0.2 mm. Anyway, the LMS9DS1 has a pitch of 0.43 mm, but its open space between pins is exactly 0.2 mm. Do we go by pitch, and oversize the land pads by 0.1 mm in both length and width? Or do we go by open space between pins, and not oversize t

Posted on June 05, 2017 at 15:21 Hi, I am working with LIS2DE12 accelerometer. Till now, I am able to read the raw data provided by the chip. Now, I have to detect free fall for the same. In the data sheet, I couldnt find any specific registers assigned for this purpose. The only thing I could find is that there are two interrupt pins available for the motion detect and free fall detect. But I dont know how to configure this interrupts. Can anyone provide me the steps for the configurations? How can I decide the threshold value for generating this free fall detect?? Thank you in advance!!!

Posted on June 09, 2017 at 05:24I have using DM00171283 and I have requirement to operate accelorometer sensor for FIFO,stream,stream to FIFO and FIFIO bypass mode with 1hz,10hz and 25hz frequency with i2c protocol. Moreover, I have also operate this sensor for normal,high and low power mode for INT1 or INT2. So, for that I have configure some register value but I have not get proper data from it. Is there any conversion formula for x,y,z axis to be read?.Following registers which I have configure:I2C_WriteByte(&ctrl_1,1,0x77);//low power 400hz I2C_WriteByte(&ctrl_5,1,0xC0);//FIFO enable I2C_WriteByte(&fifo_ctrl,1,0x40);//mode selection I2C_WriteByte(&ctrl_3,1,0x06);//interrupt generate    and then I have read all three axis valueI2C_ReadByte(&x_axis_L,1);I2C_ReadByte(&x_axis_H,1);I2C_ReadByte(&y_axis_L,1);I2C_ReadByte(&y_axis_H,1);

Posted on June 08, 2017 at 16:07I have configure all register of IIS2DH accelerometer according to requirement but can not able to sense motion. So,could you help me for configuration in all modes or at least example for one complete mode so I can understand better.Moreover, I would like to configure in all sensitivity values for 1hz,10hz,25hz. I also want some conversion formula for reading x,y,z axis if applicable to motion sensor.

Posted on June 08, 2017 at 07:55HI The main development is done on Android.The order company asks me to calibrate the acceleration sensor.Looking at the contents of the source, I can see 'st_calibrationtool'. Is this an APP?If so, where can I get the 'st_calibrationtool' app?If not app, how is it possible to guide how to calibrate the acceleration sensor?#lsm6ds3 #calibration #app

Posted on June 02, 2017 at 07:35Hello,I am using following resister setting to config the LIS2DH12 to generate FIFO watermark interrupt on INT1 pin, however the INT1 pin always stays LOW, I am not sure what I am missing.INT1 is connect directly to the MCU GPIO pin which set to input.Here are the register settings I'm currently using://Enable BDU, CTRL_REG4 = 0x80LIS2DH12_SetBDU(LIS2DH12_ENABLE );// Set to normal power mode, 10bit ACC data, CTRL_REG1 = 0x00, CTRL_REG4 = 0x80LIS2DH12_SetMode(LIS2DH12_NORMAL );// Full scale selection, CTRL_REG4 = 0x80LIS2DH12_SetFullScale(LIS2DH12_FULLSCALE_2);// Enable axes, CTRL_REG1 = 0x07LIS2DH12_SetAxesEnabled(LIS2DH12_X_ENABLE | LIS2DH12_Y_ENABLE | LIS2DH12_Z_ENABLE);// set ODR to 1Hz, CTRL_REG1 = 0x17LIS2DH12_SetODR

Posted on June 08, 2017 at 04:31Hello:I am using the STLM20W87F temperature sensor in an application, basically, on a PCB to measure ambient temperature.Referring to page 10 of the datasheet, I have the sensor connected with a filter of 1000p / 10K. That output goes directly to the ADC input of the controller. My STM32F4 is sampling at 200 samples/sec. The Vref pin of the controller is at Vdd = 3.3V. At an ambient of 25C, the ADC values are around 2235 - 2260. This translates to a voltage of (2250/4095) x 3.3 = 1.81V. It seems to be high for the value in the datasheet that should be around 1.55 for T=25C. If I measure the actual voltage at the output of the STLM20W, it's pretty much spot-on at 1.59V.If I put my finger on the sensor, the counts should decrease, but barely moves. I even tried warm air from a hair dryer but nothing significant, maybe 100 counts lower. Ditto for taking some canned air and spraying on the device, the coun

Posted on June 07, 2017 at 23:23Hi everyone,For my application I used the LIS2DH12 MEMS in single click configuration. This is my setting:CTRL_REG1 = 0x5F                       // ODR=100Hz, Low Power mode, Z Y X axis enableCTRL_REG4 = 0x00                       // Full Scale(FS):+/- 2G, high resolution disable (low power mode)CTRL_REG6 = 0x82                       // Click interrupt on INT2 pin, interrupt active lowCLICK_CFG = 0x15                        // Enable interrupt single-click on X-axis, Y-axis and Z-axis CLICK_THS = 0x0D                        // Click threshold: LSB=FS/128 -> Threshold = CLICK_THS*LSB = 0.2G&

Posted on June 02, 2017 at 11:05Hi everyone !I'm working on the flightsense sensor thanks to the expansion  board X-Nucleo-6180XA1 and a satellite on a STM32F401RE. And I have some questions :I would like to know the accuracy of the sensor ?Also, I want to use it to determine a distance between the sensor and a target. I have implemented the example code and adapted it to my situation. I would like to measure the distance with at least 0.5mm of precision. But the sensor send only the result in millimeter by the I²C bus .Is it possible to have a more accurate measure ?Finally, I work on STM32F103 thanks to the SPL library and not with the HAL library. I tried to implement a code but unsuccessful ...Do you have an example with this library ?Thanks in advance,Best regards,Florian

Posted on June 07, 2017 at 15:08Hey,I am trying to use the VL6180x without an API and want to communicate to it directly by I2C. Therefore I use the USBISS. Performing measurements with single shots works fine. I can also read out the results easily by messaging the single registers. But when I try to go into continuous mode, I simply write to the register 0x018 the byte 0x03. After that I try to read out the device by contacting the 0x62-register in a for-loop, having pauses of 100 ms for each read. Sadly this always gives me the first value that has been measured (it's like the device still works in single-shot mode and I am reading out the same result over and over again).I have also set the Intermeasurement period to the smallest value.Am I forgetting something?Thanks in advance and regards!

Posted on June 05, 2017 at 18:20Hi,I am using the LSM6DSL with a SMT32L476. My question is in relation to the Sleep/inactivity interrupt.I am able to use the LSM6DSL in both sleep and wake up interruption.However is it possible to use this interrupt (Sleep/inactivity) and disable the automatic decrease of the accelerometer sampling rate to 13 Hz option.I tried to set TAP_CFG (58h) to 0x80 (INACT_EN = b00) but the interrupts are not generated anymore.Can someone please tell me if it is possible and if it is how to ?Thanks,#lsm6dsl #inactivity ##interrupt

Posted on June 05, 2017 at 11:40Hi,reading data from L3G4200D i observed some spikes.So i set the BDU :I read before MSB and then LSB for X, Y, then Z such as described in the datasheet.reading the status_reg to know when new data is available i saw that STAUS_REG is alwais 0xFF.This means that :    ZYXOR ZOR YOR XOR ZYXDA ZDA YDA XDA    are all set.    what is the correct usage of this register ?

Posted on June 01, 2017 at 13:56Hi All,I wanted to use LPS25HB for measuring the pressure of foot stroke while running. Can this sensor be used for the same. Is this activity realizable using this sensor ?. I checked the datasheet and it said it is a kind of digital output barometer. ThanksRahul

Posted on May 30, 2017 at 11:39I'm working on LSM303AGR mems and I've some reading problems: when I read x, y, z accelerometer registers in 'normal mode' I get lots of 0 and sometimes a correct value (z value have to be about 1G, not 0), when I set 'low-power' mode everything works good.Any ideas?Thank you.NFP.S. Attached I leave two example: work.png is in 'low-power mode', the other is in 'normal mode'.#mems #i2c #accelerometer #sensor #lsm303agr #read

Posted on May 29, 2017 at 11:13Hello, I am using two LIS2DH12 sensors in my project. I am using I2C communication interface. The one with the address pin high (IC4, address 0b0011001x) is working OK, but the one with the address pin low (IC5, address 0b0011000x) is not communicating. It does not even ACK the address. I tried swapping the IC for a new one or even swapping the entire PCB but the problem persists. What could I be doing wrong?

Posted on March 31, 2017 at 07:49I've been able to get the LIS3DSH working for single values by doing this: transmitData[0] = (uint8_t) (LIS3DSH_READ | LIS3DSH_X_L); SPISend( transmitData, receiveData, 2); xl = receiveData[1];But if I wanted to read out multiple values in one transaction, I'd expect that I could do something like: transmitData[0] = (uint8_t) (LIS3DSH_READ | LIS3DSH_MULTIPLE | LIS3DSH_X_L); transmitData[1] = (uint8_t) (LIS3DSH_READ | LIS3DSH_X_L); SPISend( transmitData, receiveData, 3); xl = receiveData[1]; xh = receiveData[2];Or have byte 2 just be 0xFF because the auto-increment would do what I expected.But alas, it doesn't work. (yes address increment is turned on in register 6)Can this be done? What am I missing?Now for documentation, the temperature register just isn't documented in the data sheet. It took a while to figure out that it is Celci

Posted on May 30, 2017 at 14:35Hello Engineer's,                             I have IIS2DH IC interface with STM32LOXX Controller through I2C mode. Pin Details bellow:          IIS2DH (Pin)      --      M/C (Master)         1. SCL/SPC         -     SCL(I2C)         2. CS                    -     Vss(+3V)         3. SDO/SAO       &nb

Posted on May 05, 2017 at 18:05I am trying to connect the EVALSTPM34 SPI interface to a microprocessor board that has a PMOD interface (see attachment) that is configured to support SPI.===========================================================PMOD SPI Interface to EVALSTPM34 Metering Board===========================================================Set rotary switch to 2MASTER             SLAVE(freja board)         (EVALSTPM34 board) PMOD J6 'SPI'1 (SS) ------------> (SCS) 52 (MOSI) ---------> (MOSI) 23 (MISO) <---------- (MISO) 44 (SCK) -----------> (SCL) 6                               (GND) 3                               (VCC) 10