Skip to content

Accelerometer in API 6

The accelerometer measures acceleration in three axis and can help you detect movement, vibration, tilt, and more.

Overview

Accelerometer functionality:

  1. There are three reed switch-based User modes: Reed switch on/off (+ WiFi variants), Reed switch counter and Reed switch pipeline. Overview below.

  2. Accelerometer data can be sent as appended payload.

    More about appended payload HERE!

  3. Two independent alerts are sent by the accelerometer.

    1. Tilt alert - set up by register 0x3E, works with a tilt threshold in degrees
    2. Tracing alert - works like the Trace me mode, but independent, set up with register 0x56

    More about independent alerts HERE!

User modes

Info

WiFi-enabled variants of several of these modes exist - see the Comparison of Mode Types for more information!

Guard me (+ WiFi variants)

Very simple: when movement is detected in any way by the accelerometer, an alert is immediately sent. After this, the device is inert for the duration of the sleep time.

Track me (+ WiFi variants)

Sends an alert when the monitored object starts moving and one when the movement stops. The device needs to be still for the duration of arrival delay in order for the stop message to be sent.

Trace me (+ WiFi variants)

Similar to Track me, sends alerts on both start and stop of movement. In addition to this, this modes also sends periodical messages while the device is moving until it stops.

Monitor me

Records the intensity of vibration in short time periods and sends a full report message once every 42.5 minutes. This message can be decoded to get the intensity of vibration in % in 4.25 minute intervals. A total of 10 time intervals is sent in every message.

Put me back

Sends an alert when movement is detected and after there has been no movement for the duration for some time (arrival delay), sends a stop message with data from the accelerometer. This data is used to determine whether the object returned to its original position.

Don't drop me (+ WiFi variants)

This mode allows you to set an acceleration threshold and a duration timer. There are three submodes, the alert is sent when these conditions are met:

  1. Shock: Measured acceleration < threshold for longer than the duration.
  2. Free fall: Measured acceleration > threshold for longer than the duration.
  3. Click: Measured acceleration < threshold for no longer than the duration.

Travel time

Similar to Trace me, but also has redundancy and counts time spent moving and while still, sends a total of 5 travel time bytes. Also counts the total number of movement cycles.

Relevant registers

Register hex Register name Value range What it is and what it does Useful for
0x03 Arrival delay SimpleTime Time between movement stop and stop of movement alert. Track me, Trace me, Put me back, Travel time
0x04 Sleep time SimpleTime Time after message during which no events that would normally trigger a message are noticed in order to save the battery All accelerometer modes
0x05 Tracing interval SimpleTime Interval of periodical messages sent while moving Trace me, Travel time
0x11 Accelerometer sensitivity (all axis) Number 1-255 General sensitivity for all three axis X, Y, Z. Recommended values 5-30. All accelerometer modes
0x12, 0x13, 0x14 Accelerometer sensitivity (axis X, Y, Z) Number 1-255 Same as above, but changes the sensitivity of only one axis. All accelerometer modes
0x15 Drop me threshold Number 1-255 Depends on submode. Acceleration threshold to trigger message. More info in mode documentation. Don't drop me
0x16 Drop me duration Number 1-255 Depends on submode. Duration to trigger message. More info in mode documentation. Don't drop me
0x17 Drop me axis configuration 0x01-0x0A, 0x41-0x4A, 0x81-0x8A Submode and sensitivity configuration. Mode info in mode documentation. Don't drop me
0x3C Accelerometer measurement interval SimpleTime How often the sensor wakes up. All accelerometer modes
0x3E Tilt threshold 0x00-0xB4 Tilt threshold in degrees. Range is 0°-180°. Tilt threshold independent alert
0x49 Accelerometer detection delay SimpleTime Currently works in Travel time only. Specific function, please check mode documentation for more info. Travel time
0x56 Device control 8 binary flags Bit 0 turns on independent Trace me alerts. All modes