RE: ACE - Blog #8 - Offloading computation to LSM6DS3

TobiasR — Sun, 03 Sep 2023 12:21:33 GMT

Thanks for the nice blog post.

I'm trying to detect free falls with my XIAO nRF52840 which has the LSM6DS3 included.

However, I can't make it work to receive an interrupt for this. (Double) Taps work fine but the free-fall detection never interrupts anything.

Even the sample code from the libraries doesn't result anything (it compiles, just does not trigger).

I even asked in forums like here

https://forum.arduino.cc/t/lsm6ds3-free-fall-detection-not-working/1163290/7

and

https://forum.seeedstudio.com/t/xiao-nrf52840-free-fall-detection-not-working/272103

but you seem to be the "reference to go":

My current code looks like that, just in case you see anything I messed up or forgot.

Thanks for any help!

---

#include "LSM6DS3.h"

#include "Wire.h"

LSM6DS3 myIMU(I2C_MODE, 0x6A);

#define int1Pin PIN_LSM6DS3TR_C_INT1

volatile uint8_t interruptCount = 0; // Amount of received interrupts

uint8_t prevInterruptCount = 0; // Interrupt Counter from last loop

void setup() {

Serial.begin(9600);

while (!Serial) {

; // wait for serial port to connect. Needed for native USB port only

}

Serial.println("--- START ---");

pinMode(LED_RED, OUTPUT);

pinMode(LED_GREEN, OUTPUT);

pinMode(LED_BLUE, OUTPUT);

setLedRGB(false, false, true); // set blue led

myIMU.settings.accelEnabled = 1;

myIMU.settings.tempEnabled = 1;

myIMU.settings.gyroEnabled = 1; // Gyro currently not used, disabled to save power

if (myIMU.begin() != 0) {

Serial.println("IMU error");

} else {

Serial.println("IMU OK!");

}

setupFreeFallInterrupt();

pinMode(int1Pin, INPUT);

attachInterrupt(digitalPinToInterrupt(int1Pin), int1ISR, RISING);

}

void loop() {

setLedRGB(false, false, true); // reset led to blue only

Serial.print("\Iterrupt Counter: ");

Serial.println(interruptCount);

// if interrupt was received in this cycle

if (interruptCount > prevInterruptCount) {

Serial.println("\Interrupt received!");

setLedRGB(false, true, false); // set green only

}

prevInterruptCount = interruptCount;

if (interruptCount >= 5) {

// Trigger System OFF after 5 interrupts

goToPowerOff();

}

myIMU.writeRegister(LSM6DS3_ACC_GYRO_TAP_CFG1, 0x01); // LATCHED

delay(500);

}

// -------------------- System ------------------------- //

void goToPowerOff() {

setLedRGB(false, false, false);

Serial.println("Going to System OFF");

setupFreeFallInterrupt(); // not needed here, if already applied..

delay(100); // delay seems important to apply settings, before going to System OFF

//Ensure interrupt pin from IMU is set to wake up device

nrf_gpio_cfg_sense_input(digitalPinToInterrupt(int1Pin), NRF_GPIO_PIN_PULLDOWN, NRF_GPIO_PIN_SENSE_HIGH);

// Trigger System OFF

NRF_POWER->SYSTEMOFF = 1;

}

// -------------------- Interrupts ------------------------- //

void setupFreeFallInterrupt() {

uint8_t error = 0;

uint8_t dataToWrite = 0;

dataToWrite |= LSM6DS3_ACC_GYRO_BW_XL_100Hz; // 0000 0001 200Hz

dataToWrite |= LSM6DS3_ACC_GYRO_FS_XL_4g; // 0000 0000 2g

dataToWrite |= LSM6DS3_ACC_GYRO_ODR_XL_104Hz;// 0100 0000 104Hz

error += myIMU.writeRegister(LSM6DS3_ACC_GYRO_CTRL1_XL, dataToWrite);

error += myIMU.writeRegister(LSM6DS3_ACC_GYRO_WAKE_UP_SRC, 0b00100000);

error += myIMU.writeRegister(LSM6DS3_ACC_GYRO_TAP_CFG1, 0b00000001);

error += myIMU.writeRegister(LSM6DS3_ACC_GYRO_WAKE_UP_DUR, 0b00000000);

error += myIMU.writeRegister(LSM6DS3_ACC_GYRO_FREE_FALL, 0b000110);

if (error) {

Serial.println("Problem configuring the device.");

} else {

Serial.println("Device O.K.");

}

void int1ISR()

{

interruptCount++;

}

// -------------------- Utilities ------------------------- //

void setLedRGB(bool red, bool green, bool blue) {

if (!blue) { digitalWrite(LED_BLUE, HIGH); } else { digitalWrite(LED_BLUE, LOW); }

if (!green) { digitalWrite(LED_GREEN, HIGH); } else { digitalWrite(LED_GREEN, LOW); }

if (!red) { digitalWrite(LED_RED, HIGH); } else { digitalWrite(LED_RED, LOW); }

}

RE: ACE - Blog #8 - Offloading computation to LSM6DS3

javagoza — Mon, 24 May 2021 17:44:49 GMT

Hi,

I recommend you to use Sparkfun Library

https://github.com/sparkfun/SparkFun_LSM6DS3_Arduino_Library

There is a sample of free fall detection

https://github.com/sparkfun/SparkFun_LSM6DS3_Arduino_Library/tree/master/examples/InterruptFreeFallConfig

You'll have to change the I2C address to 0x6A (by default, the SparkFun module address is 0x6B). LSM6DS3 myIMU(I2C_MODE, 0x6A);

Unfortunately the two interrupt ports are not connected on the arduino board so you will have to hack it or use another approach.

RE: ACE - Blog #8 - Offloading computation to LSM6DS3

DAB — Sun, 23 May 2021 17:42:00 GMT

Nice detailed update.

DAB