LSM6DSL AWT latency problem

[RPinh]

Hi,

I'm trying to configure the AWT function in the LSM6DSL. All works fine minus the latency. I change the latency to 0x01(40ms) but the interrupts keep with a delay of 600ms(default) between each one. Any idea what I'm doing wrong?

Accelerometer band width : 100Hz

Accelerometer range : 2g

Accelerometer sample rate : 26Hz

Gyro Disabled

Configuration Reference: https://www.st.com/content/ccc/resource/technical/document/application_note/group0/26/07/3f/bf/12/55/47/62/DM00402563/files/DM00402563.pdf/jcr:content/translations/en.DM00402563.pdf - page 56

Configuration code:

// Enable access to embedded registers (bank B)
    // Write A0h to FUNC_CFG_ACCESS
    ret = writeRegister(LSM6DSL_ACC_GYRO_FUNC_CFG_ACCESS, LSM6DS3_ACC_GYRO_FUNC_CFG_ENABLED_B);
    if (ret != IMU_SUCCESS)
        return ret;
 
    // Set latency
    ret = writeRegister(LSM6DS3_ACC_GYRO_A_WRIST_TILT_LAT, lat);
    if (ret != IMU_SUCCESS)
        return ret;
 
    // Set threshold
    ret = writeRegister(LSM6DS3_ACC_GYRO_A_WRIST_TILT_THS, ths);
    if (ret != IMU_SUCCESS)
        return ret;
 
    // Set mask
    ret = writeRegister(LSM6DS3_ACC_GYRO_A_WRIST_TILT_MASK, mask);
    if (ret != IMU_SUCCESS)
        return ret;
 
    // Disable access to embedded registers (bank B)
    ret = writeRegister(LSM6DSL_ACC_GYRO_FUNC_CFG_ACCESS, LSM6DS3_ACC_GYRO_FUNC_CFG_DISABLED);
    if (ret != IMU_SUCCESS)
        return ret;
 
    // Enable embedded functions
    // Enable AWT detection
    // Write 84h to CTRL10_C
    //writeRegister(LSM6DS3_ACC_GYRO_CTRL10_C, LSM6DS3_ACC_GYRO_WRIST_TILT_EN_ENABLED);
    ret = writeRegister(LSM6DS3_ACC_GYRO_CTRL10_C, 0x84);
    if (ret != IMU_SUCCESS)
        return ret;
 
    // AWT interrupt driven to the INT2 pin
    // Write 01h to DRDY_PULSE_CFG
    ret = writeRegister(LSM6DS3_ACC_GYRO_DRDY_PULSE_CFG, 0x01);
    if (ret != IMU_SUCCESS)
        return ret;
 
    // Enable latched mode
    readRegister(LSM6DS3_ACC_GYRO_TAP_CFG1, &buf);
    if (ret != IMU_SUCCESS)
        return ret;
    ret = writeRegister(LSM6DS3_ACC_GYRO_TAP_CFG1, (buf | LSM6DS3_ACC_GYRO_LIR_ENABLED));

#define LSM6DSL_ACC_GYRO_FUNC_CFG_ACCESS                0x01
#define LSM6DS3_ACC_GYRO_DRDY_PULSE_CFG                 0x0B
#define LSM6DS3_ACC_GYRO_CTRL10_C                       0x19
#define LSM6DS3_ACC_GYRO_TAP_CFG1                       0x58
 
 
 
/**** Embedded functions register mapping - Bank B  *******/
#define LSM6DS3_ACC_GYRO_A_WRIST_TILT_LAT               0x50
#define LSM6DS3_ACC_GYRO_A_WRIST_TILT_THS               0x54
#define LSM6DS3_ACC_GYRO_A_WRIST_TILT_MASK              0x59
 
#define LSM6DS3_ACC_GYRO_FUNC_CFG_ENABLED_B             0xA0
#define LSM6DS3_ACC_GYRO_FUNC_CFG_DISABLED              0x00
 
#define LSM6DS3_ACC_GYRO_LIR_ENABLED                    0x01

Best regards.

[RPinh]

What registers do I have to change to decrease the reaction time of the INT2? With this configuration, I have a reaction time of approximately 600ms(When I receive an interrupt in the MCU I read the FUNC_SRC2 to clean the interrupt). I need a reaction time of approximately 100ms. Is possible?

[RPinh · Accepted solution]

Hi,

Found the problem. The problem was that the pin of the INT2 in the MCU have debounce timeout.

Best regards.