MEMS (sensors)

Posted on February 23, 2018 at 21:28 The INT1_THS register value does not seem to change the threshold at which an event is triggered. I can read and write the INT1_THS(0x32) so I know my writes are working. I poll the INT1_SRC register and watch the bits change so the position enable ints are working it is just that the threshold seems fixed not adjustable. INT1_CFG = 0xCF to enable X & Y position triggering INT1_THS = 0x20 = 0.5g or 30 degrees. (actual int flags trip around 0.94g/66 degrees) Thanks in advance for any help. Note: this post was migrated and contained many threaded conversations, some content may be missing.

Posted on December 01, 2015 at 22:29HiIm having some trouble confirming whether the resolution from the accelerometer in the LSM9DS1 and also LSM6DS3 is actually 16 bits ?The datasheet for both sensors say the output resolution is indeed 16 bits, but in an ST catalog online I found a line saying that the gyroscope has 16 bits but the accelerometer has only 14 bits.Can anyone please confirm? we are going to production now and this info is vital. Cheers!

Posted on April 03, 2018 at 04:41I am writing a bit banging SPI driver for the HTS221 with no success,I drive the SDO data just before the falling clk endand I read the SDI data on the rising clk edge. I have included a screen capture of the Saleae logic analyzer..which shows (what I believe to be a typical initialization) setting the reading cntrl1 and writing cntrl1 with PD= 1, but I am not seeing the correct response from the who am I request.

Posted on April 12, 2018 at 10:46Dear all,referring to the LSM303C data sheet, I'd like to know what exactly is to be understood with 'The system can generate an interrupt signal for ... magnetic field detection'.I am interested in an application where we can use the magnetometer's interrupt to wake up on a device rotation (i.e. when the measured direction of earth's magnetic field changes).From the data sheet I know that a positive threshold value R for interrupt generation can be configured using the registers INT_THS_L_M and INT_THS_H_M.My question is, if R is absolute (i.e. magnetic field in X, Y or Z direction is >R or <-R) or relative (i.e. deviation since interrupt activation in X, Y or Z direction is >R or <-R).Thank you and kind regards,Thomas#lsm303c #magnetometer

Posted on April 10, 2018 at 17:13I have been doing some testings recently with the LIS3DH accelerometer to measure machine vibration, and I have come across 2 things. I am using the accelerometer to sample 512 points at a 1.1Khz sampling rate. I have it set a normal mode, with ODR =1.3Khz, out of the 512 points I sometimes get 1 or 2 outlier points with very different values from the rest, it seems to happen randomly but I am not sure of the source (picture attached).My second question is about the accelerometer's natural frequency as i could not find it in the datasheet.Regards.#lis3dh-machine #lis3dh

Posted on April 12, 2018 at 10:13I am trying to interface the temperature sensor using hal i2c library but unable to write to the register or get any value from the sensor. Need instant help

Posted on April 04, 2018 at 12:09Hi, I have the sensortile development kit, I wanted to test the battery life without soldering the sensortile to the cradle board, without using USB charge and with the accelerometer always active. Does anyone who has used this sensor have an idea of how long it lasts battery?ThanksDaniele#battery #steval-stlkt01v1 #sensortile #sensortile-kit #accelerometer #battery-charging #battery-life #test

Posted on April 10, 2018 at 20:41Trying to figure out how to apply the Early Convergence Estimate value for the VL6180X proximity sensor.Design Tip DT0034 gives some information, but also populates the equations with some apparent magic numbers, and doesn't give units to figure out how the calculations are to be made.From DT0034,      - What are the factors of 24, 70 and 200 in the TIME calculation.      - What is the unit of time for PERIOD (ms?) and why is multiplied by 10 in the TIME calculation      - What is the unit of time for MAX_CONV and why is is multiplied by 1000 in CONV_TIME calculation (ms to us conversiton?)      - Might assume that the 500 in ECE_THRES is 0.5ms *1000 to put it in microseconds, but not sure.      - What are the 100 multiplicati

Posted on March 29, 2018 at 13:03Hi thereI'm developing an ultra-low-power minituarized system witch includes the LSM303AGR. since the power comes only from a small battery, the sleep-current of the LSM303AGR is too high, therefore we want to power down it's power supply when it's not used. Unfortunately there is a RTC on the same i2c bus , which obviously can't be powered down. so the data-communication on the i2c bus should work, even when the LSM303AGR on the same bus has no power supply.Shut down VCC of the LSM303 doesn't work, because the chip gets powered through SCL,SDA and its ESD-protection diodes. What I do now, is to the put the GND-pin of the sensor to an I/O  of the MCU. When the sensor is not in use, i put the MCU-I/O in High-Z state to cut the Sensors power-supply. the sensor is then powered down.Unfortunately, if I try to communicate with the RTC over i2c, the MCU isn't able to pull-down the i2c for t

Posted on April 10, 2018 at 04:14     When I was doing impact testing, using the 16g range, with my device gently knock on the desktop, the acceleration values read have acceleration values of more than 10g, a bit unbelievable, acceleration reading and conversion are in accordance with In the manual, there should be no problem. When the plane is laid flat, the X and Y axes tend to be 0, and the z axis is about 1G. What causes this?

Posted on March 23, 2018 at 07:53The purpose is to detect the car accident while ignore the normal acceleration variance during car driving. I know there is a high pass filter in the lis3dx sensor, and the cut-off frequency can be changed by setting the following register (with actual cut-off frequency related to ODR setting) but don't know how to choose the best value. I guess there is experience value for the ODR and HPCF settings in car application. Anyone have relevant experience and would like to share it with me?

Posted on April 08, 2018 at 08:261) CTRL_REG3 (22h)Can I set both I1_IA1 and I1_IA2? 2) What is I1_321DA? 3) Our project uses two threshold, one for stronger force (e.g. collision), the other for weaker force (e.g. impact). I assume I should set INT1_THS and IT2_THS to the high/low threshold. But should I use both event on INT1 or separately e.g. INT1 for high event and INT2 for low event? 4) If INT1_THS is set to high threshold and INT2_THS is set to low threshold. The duration is set to same. So the trigger will satisfy INT2_THS firstly then IT1_THS. In this case, will the lis3x device generate two interrupt with IA1 first and IA2 second?

Posted on April 03, 2018 at 09:47In Low-power mode and Normal mode, the BW is equal to ODR/2 which is understandable. But in HR mode, the BW is ODR/9, why?

Posted on April 08, 2018 at 13:13I encountered a problem that IG2 doesn't get detected on either INT1 or INT2 pin. I confirm the IG1 work on both INT1 and INT2. Followings are the combinations I tried (CTRL REG1,2,4,5 kept unchanged):The INTx_CFG,INTx_THS, INTx_Duration are set same for IG1 and IG2.1) CTRL_REG1 - CTRL6{     0x57,      0x39,     0x40, //IG1 route to INT1     0x00,     0x40, //Enable FIFO mode     0, //Disable INT2 }In this configuration, IG1 is correctly detected on INT1 pin.2) CTRL_REG1 - CTRL6{     0x57,      0x39,     0x20, //IG2 route to INT1     0x00, &nb

Posted on April 08, 2018 at 18:01Has anyone developed STM32 code for the AIS1120SX accelerometer?-Bruce#accelerometer-ais1120sx*

Posted on October 16, 2017 at 14:15Hello,I am trying to log accelerations above 2g. To do so I parametrized the LIS3DH as following:- CTRL_REG0: 0x10- CTRL_REG1: 0x57 (100Hz + Xen + Yen + Zen)- CTRL_REG2: 0x00- CTRL_REG3: 0x40 (IA1 on INT1)- CTRL_REG4: 0xB0 (BDU + FS +/- 16g)- CTRL_REG5: 0x08 (INT1 Latched)- CTRL_REG6: 0x00- FIFO_CTRL_REG: 0x00- INT1_THS: 0x0A (+/- 16g  => 186 mg/LSb, 2000/186 = 0x0A)- INT1_DURATION: 0x00 (trigger INT1 as soon as the acceleration goes above threshold)- INT1_CFG: 0x2A (OR combination + Z high event + Y high event + X high event)Everything works fine, I get interrupts signals, read the acceleration available inside the corresponding buffers, clear the interrup. Whereas, I do not understand some results that I get.First issue, I do not understand how the sensitivity for the +/-16g is obtained. For the other full scale m

Posted on April 08, 2018 at 07:55I am using the LIS3MDL sensor for vehicle monitoring on parking spaces. When testing, I discovered that hysteresis occurs when the magnetic field on the sensor changes by more than a certain amount. When I recover the magnetic field, the sensor's detected value does not return to its original value.I have read the datasheet and an AN4602,but have no idea, and I couldn't find a description of the hysteresis self-correction in it. I would like to ask if there is a way to make the sensor degaussing through software and restore the original state when hysteresis occurs.Thank you...#lis3mdl #magnetic

Posted on April 02, 2018 at 21:07Hi!I had a previous post asking how to interpret the values being drawn from the chips registers and I was able to get that working. (https://community.st.com/0D50X00009XkWYOSA3 )However, it only works as a 360 degree compass when it is perpendicular to the Z axis (right-angled to ground; almost operating/rotating in the X/Y axis). It works a treat when rotating around the X/Y axis but I need it to be rotating around the Z-axis (ironically when the chip is perpendicular to ground i.e. flat). Any ideas? Is this common or am I missing a step such as calibration etc?Datasheet: http://www.st.com/resource/en/datasheet/lsm303agr.pdf Calculation:

Posted on April 05, 2018 at 02:02I'm currently testing the LIS2DH12 for a project concerning shock detection and measurement.My first question is:Which scaling factor do I have to use at the threshold registers and which one at the readout values for +- 16 g, Low Power mode (LP). Do I get this right that they are different?Readout values: 192 mg / LSBThreshold registers (INT1_THS, INT2_THS): 186 mg / LSBMy next question is about the maximum valid rangeI tested the maximum readout values at +-16 g in low power mode at 5376 Hz.Inside the OUT register I do have 8 bit-values of +127 or -128 at one or two out of the 3 axis.That would mean: 127 x 0.192 g = 24.384 gIs this value still correct because it's a bit more than 10 % above the maximum range of +- 16g?Many thanks in advance for your help!

Posted on May 06, 2017 at 22:23Hello,I'd like to ask you about opinion on accuracy of HTS221 sensors, both factory mounted on X-NUCLEO-IKS01A1 boards (powered by Nucleo board @ 3.3 V).I get quite surprising results from these sensors, compared to reference designs with SHT21 and SHT31 sensors (which are obviously calibrated similar way, because in stable environment their output is no different than 0,2 centigrades and 1 % rH from each other).HTS221 Sensor 1Calibration values:H0 = 30 %, ADC output 0xFFF8H1 = 72 %, ADC output 0xD001Real-life application values (ambient conditions):0xCFF0 output = 72 % rH , while SHT21 and SHT31 showed 59 % (which is about 22 % error)0x9C80 output = 117 % rH, while SHT21 and SHT31 showed 91 % (which is about 28 % error)HTS221 Sensor 2Calibration values:H0 = 32 %, ADC output 0x0005H1 = 73 %, ADC

Posted on March 29, 2018 at 23:41Hello, I'm using an LSM303AGR thru I2C, and after a little struggling, everythings looks fine. I can read any of the 6 axes with what seems to be the right values, and the read values react correctly when I tild my board.So, why am I always getting a failure when executing the self-test procedure given in the datasheet ? I notice that the kind of failure depends on the tilt of the PCB: I sometimes gets a fail with the magnetometer, and other times I gets a fail with the accelerometer: the read values doesn't comply with the expected range...Any idea, anyone ?Thanks!#fail #self-test #lsm303agr

Posted on April 03, 2018 at 13:20in what documentation is written about it?#storage-life

Posted on March 22, 2018 at 08:57Hi, This question is regarding the e-packaging of the LSM9DS1 sensor PCBA Instead of packaging it in the plastic casing, We are planning to cover the PCBA with the overmolding material to cover the whole PCB including the sensor to protect it from moisture and environment.Is overmolding advisable over the LSM9DS1 sensor given that it is a MEMS? If yes, do you suggest any specific material and process?#lsm9ds1 #overmolding #packaging

Posted on April 02, 2018 at 21:52I'm currently trying to configure the LIS2DH12 sensor to enable high and low interrupt on all axis.My target is to implement a shock detection and therefore I plan to use all axis (x,y,z) and as well high and low thresholds to detect every possible shock.Therefore I configure the active interrupts at INT1_CFG (I'm only using INT1 as I plan to use INT2 for a tilt detection).For this reason I wanted to program the INT1_CFG register with 0b00111111.Unfortunately when I program '0b00111111' no interrupt will be triggered (ISR not executed).I tried the following combinations:// setup INT1_CFGdata = 0b00111111; // all axis -> not workingdata = 0b00101010; // only high interrupts for x,y,z -> works data = 0b00010101; // only low interrupts for x,y,z -> not workingdata = 0b00101000; // only high interrupts for y,z -> works// not

Posted on March 30, 2018 at 18:51I have the LIS3DH accelerometer set for no FIFO, X,Y & Z output, Hi Res. I have BDU turned on.I am reading the high byte of each axis and getting the expected data which changes with accelerometer position. In all cases, the data represented by the four bits in the high side of the low register seem completely random and change to any value between 0 to 15 on every read.I have tried different data rate speeds, but that had no effect. I also tried 10 bit resolution and that gave similar results.I can't find anything that could be causing this effect in the config registers. I don't know what else I could possibly try to get stable data.I am grateful for any suggestions offered. Thank you.