MEMS (sensors)

Posted on August 16, 2017 at 16:36Hey,I am having the VL6180X Satellites sensor for ranging measurements. After connecting it, I receive some measurement values - but they are the wrong ones. The sensor isn't reacting to changes in a distance between 0mm and ~50mm. It keeps showing me the value '4 mm'. Beyond that distance of 50 mm, the values start increasing, which is fine.Is there anything I am forgetting? I have set the Offset to 0 mm. The range-ignore features and the early convergence are disabled (by register 0x02D). I performed the measurements in the darkness.Thanks in advance!#close-measurement #vl6180x

Posted on January 02, 2018 at 13:02Hi. Happy new year !I'd like to use one of ST compass + accelerometer chip (2 in 1) for implementing with one of analog device gyroscope in Kalman filter. Which sensor do you offer?  what is the criteria of choosing the right sensor? i need most accurate and stable one.Ragards

Posted on November 30, 2017 at 16:48We've noticed that the datasheet states the following about I2C timings:tBUF - Bus free time between transmissions must be minimum 1.3msFor a 400kHZ I2C transmission, that sounds quite a long wait between frames...Is this OK, or is it an errata?If not wrong, what could then happen if this tBUF is not respected?Thanks in advance#vl53l0x #i2c #vl53l0x-x-nucleo-53l0a1

Posted on November 30, 2017 at 16:39Hi.We have integrated a VL53L0X TOF sensor, and we are getting very surprised when measuring current consumption.In the datasheet there is no mention to current consumption when GPIO1 is configured to interrupt.We are using the sensor in Continuous Timed Ranging, and we want to be interrupted in the CPU when a threshold is passed.We have tested the device in CONTINUOUS TIMED and with INTERRUPT_OFF, and the current consumption is OK: just few uA when not measuring (inter-measurement period), and 15-20mA during measurement (about 33ms).But when we configure INTERRUPT to any value different from OFF, then the inter-measurement current consumption raises up to 2mA approx. Nothing is stated in ST application notes or datahseets about this.Pins and pull-ups are configured as suggested in the datasheet.Can someone from ST confirm whether this 2mA consumption is OK or not for th

Posted on December 09, 2017 at 19:30Hey there,I'm working with my STM32L476 and the VL53L0X rangngs sensor.I'm using the Example from X-CUBE-53L0A1. I don't have the Nucleo board for the Sensor just a satellite board.  When using the example for ranging with the example 'RangingWithSatellites'  I get the error shown in the picture. What am I doing wrong. The sensor is connected correctly, and the program should work. Thanks for the help. #vl53l0x #stm32l476

Posted on January 01, 2018 at 04:43Hi everyone!When i  send the 0xBE to the HTS211 with I2C, but there is no the ACK from the sensor , the I2C picture just like this.what is the matter?

Posted on December 29, 2017 at 10:33HelloPin 2(CS) and 3(SDO/SA0) how to connect this two pin with micro controller in i2c configuration. ThanksNitin Kanani#accelerometer #lis2d #st-mems #lis2d12 #gyroscope

Posted on February 22, 2017 at 13:31We're using LIS2DE12 in our device and manage to get reasonable acceleration data, interrupts etc.However, when we try to read the temperature form the designated register, we clearly get wrong results.Here is what we try to do:1. write 0xC0 to TEMP_CFG_REG.2. write 0x80 to CTRL_REG4.3. read OUT_TEMP_L.4. small delay (**we tried with and without it, with no seeming affect**).5. reading OUT_TEMP_H and treating its value as the temperature.Can someone point out if we're doing something wrong in the process?Also - do we need to treat the outcome differently? the manual says 'Temperature data is stored inside OUT_TEMP_H as two’s complement data in 8-bit format left-justified', but i'm not sure I understand the meaning of this. If someone could give an example with actual numbers that might be helpful.Fin

Posted on December 19, 2017 at 17:50Hello,I am using nRF SDK 12.2.0 , with nRF52832 on pca10040 hardware, and working with the example in examples/peripheral/spi/main.c to develop a driver for LIS2DE12. When I write a hexadecimal value I find a problem. I checked with the scope that CS, MOSI and SCK are correct, but I get 0xFF on MISO line .Any ideas what to check?#lis2de12 #miso #spi #nrf52

Posted on December 28, 2017 at 10:11I have this http://www.kynix.com/Parts/3294011/SIT8009AC-11-18E-125.000000E.html MEMS oscillator at 125MHz frequency (also the same with an OSC52 from SiWard at 25MHz) followed by a 1-to-4 clock driver to distrubute the clock to multiple ICs.When layouting, I always find myself asking what is the 'best' layout practices for them, since they are high speed signal sources and since I almost always have EMC problems related with these frequencies. This doesn't mean of course that the source of the problems are these oscillators. But I nevertheless look for ways to improve the layout at this corner.Do you have any specific guidelines you follow when you layout such components?Some of which I use are the following: The driver is physically plac

Posted on March 21, 2017 at 12:28Hi,Recently I worked on LSM9dS0, LSM9dS1 and LM303D sensor.Now, I have LSM9dS1 raw data from Accelerometer, Gyroscope & Magnetometer. Project is based on car driving safety system. So I want to know how can I calculate the Acceleration from LSM9sS1 in terms of Km/hr. Later, I want to detect some other things also like Accident detection, Rash Driving, Car tow, Harsh braking using sensor fusion application.Please share your opinion. Thank you.#lsm9ds1 #sensor-fusion

Posted on December 13, 2017 at 10:27HiI'm using LSM6DS3 for activity detection.The SLEEP_STATE_IA bit of the WAKE_UP_SRC register is used to monitor the activity/inactivity,but I have noticed that the value for the bit remains the same(ie when sleep event is detected the value of SLEEP_STATE_IA is set to 1 but even when activity is detected the value remains the same)Can you suggest a fix for the problem? OR provide an alternative for activity detection

Posted on December 22, 2017 at 02:24Now I want achieve tilt remedy function. I did as the following:1,tilt the sensor with a constant angle.2, In initialization function:set ODR,set mode nomal ,set full scale(+/-2g),enable x,y,z axis,set LIS3DH_CTRL_REG2=0x48 ( HPM[1:0]=[01],Reference signal for filtering),set REFERENCE =0;set THR = 2。enable X and Y interrupt . enable IA1 to INT1 .3, In tilt remedy function:check IA interrupt flag;if IA interrupt occured , set THR with THR+1.loop up line until interrupt not occured.set the REFERENCE regesiter with the value of current THR ,resume the THR register with value 2.by now , IA interrupt should not occured. because the the difference between the input acceleration and the content ofREFERENCE is 0. but actually the IA interrupt always occured. How to resolve it?Thanks!

Posted on December 21, 2017 at 17:01What is Mic level in sensor tile represent ? The audio noise in db in particular as per this formula DBNOISE_Value_Ch[NumberMic] = (uint16_t)((120.0f - 20 * log10f(32768 * (1 + 0.25f * (AUDIO_VOLUME_VALUE /*AudioInVolume*/ - 4))) + 10.0f * log10f(RMS_Ch[NumberMic])) * 0.3f + DBNOISE_Value_Old_Ch[NumberMic] * 0.7f);How did you arrive at this formula ? The acquired PCM sample values are squared and then divided as per this formula RMS_Ch[NumberMic] /= (16.0f*MICS_DB_UPDATE_MUL_10MS*10); which is the mean calculation and how does this relate to RMS value?Can we use the PCM sample values to calculate the Sound pressure level and classify the sound ?

Posted on October 22, 2017 at 05:12       I have found a puzzling problem while I reading the document AN3308,On page 17,table 9.In my opinion, 1g come from the formula : a = (0x4000 -> 0x400 = 1024)*2000mg/2048.So get the correct value : 1g , In the same way, 350mg should come from: a = (Ox15e0 -> 0x15e = 350)*2000mg/2048 , but the calculation is 341.8,not equal to 350.       Another problem is that I have received 12bit data(so as: OxFFF0...) from LIS3DH while I config it working in normal mode (10 bit)      Anyone can help me explain it ?  thanks !

Posted on December 19, 2017 at 13:56I am not understanding the concept of normal, low and high mode for the motion sensor IC LIS2DH12.Can anyone please give me some idea about this concept.

Posted on December 20, 2017 at 17:00Hello!I am trying to detect a collision and generate an interrupt on INT1, and also to detect motion and generate an interrupt on INT2. INT1 is working normally, but INT2 does not work. It seems I am missing something...These are the values I put at registers: CTRL_REG0 = 0x90  // Pull-up disconnected to SDO/SA0 pinCTRL_REG1 = 0x27 // HR / Normal / Low-power mode (10 Hz), Z-axis enabled, Y-axis enabled, X-axis enabledCTRL_REG2 = 0x01 // High-pass filter enabled for AOI function on interrupt 2CTRL_REG3 = 0x40  // IA1 interrupt on INT1 enabledCTRL_REG4 = 0x88 // Output registers not updated until MSB and LSB reading, high-resolution enabledCTRL_REG5 = 0x00 // Normal mode, FIFO disabled, interrupt request not latchedCTRL_REG6 = 0x28 // Interrupt 2 function o

Posted on December 18, 2017 at 14:24We are currently replacing the LPS331AP in our design. we favour the the LPS25HB. i'm working with the STEVAL-MKI165V1 Kit, which is directly connected to our board. The pressure seems to be in a reasonable range but the temperature readings are really off.The LSP25HB measures a temperature of only 18.06�C while the old LPS331AP measures 23.53�C and the LSP25H measures 22.8�C.The datasheet states a accuracy of +/- 2�C. Which is true for LPS25H, but the LPS25HB is 6 �C off.I found no difference in software (referring to the datasheet) between LPS25HB and LPS25H regarding initialization or conversation.Why is there such a big temperature difference? The temperature measurement is quite important for us, and we do not have the space to put an extra temperature sensor on the board.We even bought a second evaluationkit of the LPS25HB to verify our measu

Posted on December 18, 2017 at 15:26Hi,  I am using LIS2DH12TR accelerometer. I am testing self test values.When self test mode is disabled, the axis values:Ax:100By:80Cz:90When self test mode is enabled in self test mode 1, the axis values:Kx:120Ly:95Mz:80Kx > Ax , Ly > By but  Mz < Cz Can this happen on a robust accelerometer?if Kx >Ax and  Ly> By, the Mz value must be big than Cz . Is it true?Best Regards

Posted on December 20, 2017 at 09:44Hello,I am working with the SPBTLE-RF module interfaced with a freescale IMX6 microcontroller.Right now I am porting the Beacon example code to my platform (WEC2013) and I am facing an issue with the SPI communication. When sending the Header (0x0A00000000 or 0x0B00000000), the reply from the component is 0x047F000600.My guess is that I am pulling the Chip Select too early. I have 40 microseconds between the moment when I pull down the CS and the moment of the first clock tick (cf. 'signaux I2C2-00002--00002.png' attached below, deltaX=40us).I also attach to this post 2 others screenshots of the exchange corresponding to the header. You will see that the answer from the module SPBTLE-RF starts with 0x04 instead of 0x02.Thanks for your help.Maxime#ble #bluenrg-ms #spbtle-rf #spi

Posted on December 18, 2017 at 10:18Hi everyone,I am using the lsm6dsl mems. For my application, I need to calibrate the device in order to get the more precise values. My calibration method is as follows :- I measure the +/-1g in each axe- I set the sensitivity with the full scale in LSB (from -1g to +1g)- I set the offset by comparing the top value (+1g) and the bottom value (-1g) (for example if I get -1900 and +2100, I set the offset as -100)My questions are :- Is the calibration method correct?- I observe big gaps with temperature changes (like 10 times the typical values given in the datasheet). Is it normal or there is something that I'm doing wrong?- For temperature compensation, is it reliable to use typical values given in the datasheet or should I estimate it by measurment?I hope my message is clear, sorry for my English.Swann.#calibration #lsm6dsl

Posted on December 19, 2017 at 13:40Hello,i am trying to use the FIFO of the LSM6DS3 unit and i have the following problem. I only buffer accelerometer's data so when i set the ODR for the accelerometer over 56Hz, (104, 208, 416, 833Hz etc), the buffer does not work for FIFO's ODR bigger than the accelerometers. For example if i use 104Hz ODR for the accelerometer it does not work if i choose also 104Hz(100 in the library) or above for the FIFO's ODR. I am using the Sparkfun library. In the Datasheet in page 49 it says: 'If the device is working at an ODR slower than the one selected, FIFO ODR is limited to that ODR value.Moreover, these bits are effective if both the DATA_VALID_SEL FIFO bit of MASTER_CONFIG (1Ah) andthe TIMER_PEDO_FIFO_DRDY bit of FIFO_CTRL2 (07h) are set to 0.' , so this was not supposed to be happening.Thanks in advance##lsm6ds3-#fifo

Posted on December 15, 2017 at 17:24Hi Sir/Mdm,@Please advise how many heating cycle can withstand by HTS221 humidity sensor?  Can we proposal to heat the sensor for 2nd time at 80 degree? Regard'sJason

Posted on November 19, 2017 at 02:58Hello,Is there any low power compact accelerometer available from ST that can or configured to auto detect a shake like iPhone 'undo/redo shake' and interrupt host MCU to wake up. I don't want process accelerometer raw values on the MCU to save power. My current MCU is TI's CC2640.Thanks, #shake-wake

Posted on December 13, 2017 at 12:24 Hi, I have a question about the LSM303AGR. Now, we are using the LSM303D but it will be obsolete. So we are thinking to use the LSM303AGR which is equivalent. We saw an issue with the LSM303D about the power down sequence (see FAQ below). Will we get the same issue with the LSM303AGR ? https://www.pololu.com/product/2127 Regards,