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TWELITE CUE

Questions about the TWELITE CUE series
This page summarizes questions related to the TWELITE CUE series.

What do I need for evaluation?

We recommend purchasing the following three items.

  • TWELITE CUE & MONOSTICK set MW-S-(B/R)-CUE-MS(B/R)
  • TWELITE R3 MW-LITER3
    • Adapter to connect the main unit to a PC for smooth configuration

Hardware

How to check if it is faulty?

If you can write the firmware, it may not be faulty, but if you cannot write the firmware, it is definitely faulty.

Connect to a PC using TWELITE R2 / R3 and try rewriting the application from the TWELITE STAGE APP.

What are the specifications of the pin socket?

It is for 0.64mm square pin headers with a height of 5mm. Pin headers with an exposed length exceeding 5mm may wobble slightly.

Can I obtain a version with an external antenna?

No. We do not accept custom orders regardless of quantity.

For TWELITE CUE, we publish the schematic, assuming you will create your own board.

Is the case flame retardant?

The material used complies with UL94 HB standard. It is flame-retardant but not self-extinguishing.

Configuration

How to change the settings of TWELITE CUE?

The CUE App (App_CUE) written to TWELITE CUE has two configuration methods.

Configuration is done by accessing the interactive mode of the CUE App firmware written to TWELITE CUE.

How to set a sampling frequency exceeding 190Hz?

By increasing the sampling frequency setting part of the sensor parameter (0x?3???X??) to 4 or 5, you can raise the sampling frequency to 380Hz, 750Hz, etc.

Acceleration Data

What are the conditions for acceleration measurement?

Due to constraints of the accelerometer and wireless throughput, the acceleration measurement conditions are as follows:

Continuous measurement beyond these constraints is not possible.

Also, events such as SHAKE or MOVE in TWELITE CUE mode use the internal event detection function of the accelerometer, so threshold changes are not possible. To reliably detect specific movements or vibrations, it is better to perform continuous or intermittent measurement and determine the motion from acceleration values on the receiver side.

How to obtain angles?

TWELITE CUE (in Motion Sensor PAL Mode - Acceleration Measurement) intermittently transmits only acceleration data. However, since the output data are 3-axis acceleration data expressed in mg, you need to calculate angles using inverse trigonometric functions on the receiver side.

$$\begin{align*} Pitch ( \theta ): Angle\ representing\ tilt\ in\ the\ X-Z\ plane\\ \theta &= \tan^{-1} \left( \frac{X}{\sqrt{Y^2 + Z^2}} \right) \\ Roll ( \phi ): Angle\ representing\ tilt\ in\ the\ Y-Z\ plane\\ \phi &= \tan^{-1} \left( \frac{Y}{\sqrt{X^2 + Z^2}} \right) \\ Yaw ( \psi ): Horizontal\ rotation\ around\ Z-axis\ (reference\ value)\\ \psi &= \tan^{-1} \left( \frac{Y}{X} \right) \\ \end{align*}$$

※ The yaw angle when placed on a plane cannot be calculated by the accelerometer alone.
　 The azimuth angle in the X-Y plane is calculated as a supplementary value.

We provide a Python sample script rx_cue_mot_angle.py at https://github.com/monowireless/mwings_python/blob/main/examples/typed/rx_cue_mot_angle.py.

Can it be used for vibration measurement?

Please check the measurement conditions.

The main intended use is detection of orientation and movement, and there are constraints on continuous acceleration measurement.

When transmitting continuously, the sampling frequency must be selected from 25 / 50 / 100 / 190 Hz, so frequencies higher than that cannot be supported (intermittent operation may allow a 400 Hz setting).

The accelerometer supports up to 1300Hz, but wireless throughput is limited.

Also, since intermittent operation is basically assumed, continuous transmission will drain the battery in a few hours.

TWELITE does not have a floating-point unit, so advanced FFT or edge AI processing on the MCU is difficult.

What does “intermittent 5 seconds at 25Hz” mean?

Data acquired at 0.04-second intervals are transmitted every 5 seconds.

If 16 samples are stored in one packet, 16 consecutive data points at 0.04-second intervals are included.

Why is the acceleration near 1G on one of the axes when placed on a flat surface?

Because it reflects gravitational acceleration.

Why does the acceleration not become zero when placed on a horizontal surface?

It may be affected by the accelerometer’s Zero-g offset (±40mg).

The MC3630 accelerometer datasheet (p.17) states that the Zero-g offset is ±40mg. This means that even when placed on a perfectly horizontal surface, an offset of up to about 40mg is added to the acceleration.

To account for this, record acceleration when placed on a horizontal surface and subtract the offset. The error impact on relative changes is considered much smaller compared to the Zero-g offset (refer to Nonlinearity values in the datasheet).

Why is acceleration data unstable in the initial state?

Switching from the initial TWELITE CUE mode to Motion Sensor PAL Mode may solve this. Motion Sensor PAL Mode specializes in acceleration measurement. It performs periodic measurement only and does not dynamically switch accelerometer functions, so stable operation is expected.

Changing modes requires configuration changes via MONOSTICK or TWELITE R2/R3.

How to acquire data continuously instead of intermittently?

To acquire acceleration data continuously, such as when using the TWELITE STAGE APP acceleration real-time graph, you need to change the TWELITE CUE settings.

Set to Motion Sensor PAL Mode and configure sensor parameters according to your use case via interactive mode.

How to estimate the sampling interval of continuous data?

Depending on how you use acceleration data, the following methods can be considered.

① Calculate sampling time by adding up sampling intervals from TWELITE CUE settings per sample

In TWELITE CUE Motion Sensor PAL Mode (continuous measurement), the sampling frequency applied to the sensor is specified by sensor-specific parameter settings. This value can be used.

For example, a 100Hz sampling frequency setting (0x00000200) corresponds to a 10ms interval. You can estimate sampling times by adding 10ms to the reception time of the first received acceleration sample.

This method is simple but the estimated sampling time is based on the setting, not actual measurement time. For higher accuracy, consider method ② below.

② Estimate sampling interval by dividing the time difference between start and end of measurement by total sample count

By dividing the measurement duration by the total sample count (including missing samples), you can estimate the sampling interval from actual measurement results. Accuracy improves with longer measurement periods.

③ Use the estimated sampling frequency displayed in the TWELITE STAGE APP acceleration real-time graph

The real-time graph displays estimated sampling frequency calculated similarly to ② using data from several past packets. You can record this frequency and calculate the sampling interval by its reciprocal.

④ Analyze signals output from the TWELITE CUE accelerometer using an oscilloscope

Although very difficult, analyzing the waveform of the interrupt output pin from the accelerometer on TWELITE CUE may provide the actual sampling interval.

How to open continuous data received with TWELITE STAGE APP in Excel?

While the acceleration real-time graph is open, the app automatically exports CSV files. You can open the CSV files output to the log folder in Excel.

Other Data

How to use it specifically for magnet detection?

Set to Open/Close Sensor PAL Mode. The parent outputs data as Open/Close Sensor PAL data.

Can I connect an analog input to the SET pin?

Unfortunately, the SET pin corresponds to TWELITE DIP’s #15 and does not support analog input.

Can it be used as TWELITE 2525A?

The TWELITE 2525A compatibility mode of the CUE App sends packets compatible with the wireless tag app FIFO (normal) mode. The parent outputs data according to the format mode (ASCII format) described on the next page.

In FIFO (normal) mode, usually 10 samples of acceleration data are sent at once.

The parent receives data from the Extremely Simple! Standard App unexpectedly. What should I do?

This may be a malfunction. Please contact Support.