Using External Speed Sensor Trigger Signal in STWIN.box DATALOG2

[Nandu6460]

Hello,

I am using the STWIN.box with the DATALOG2 firmware and would like to acquire data based on an external trigger signal from a speed sensor.

My speed sensor provides an open-collector output, which is connected through appropriate signal conditioning to the STWIN.box.

I would like to know:

1. What is the recommended way to use an external GPIO as a trigger source in DATALOG2?
2. Can a GPIO interrupt (EXTI) be used to start data acquisition or mark events in the recorded data?
3. Are there existing examples in DATALOG2 that use external trigger inputs?
4. Which GPIO pins are available for this purpose on the STWIN.box?
5. For an open-collector speed sensor output, should I use an internal pull-up or an external pull-up resistor?

My goal is to trigger or synchronize vibration measurements with the rotational speed signal.

Thank you.

[Jhon bruce]

For an open-collector speed sensor, I’d pay particular attention to the pull-up configuration and the voltage levels expected by the STWIN.box GPIO. An external pull-up may also be preferable if you need a cleaner or faster signal, depending on the sensor and wiring length. For synchronization, it would be useful to confirm whether DATALOG2 supports timestamping GPIO/EXTI events alongside the vibration data.

[Nandu6460]

Thank you for the suggestion.

The challenge in my setup is that the 34-pin expansion connector GPIOs are already occupied by an attached expansion board, so I cannot easily use GPIO1_EX/GPIO2_EX/GPIO3_EX.

Therefore, I am considering using the onboard RS485 interface terminals for the speed sensor connection. The sensor provides an open-collector output.

Would it be possible to reconfigure the RS485-related pins and use them as a GPIO/EXTI trigger input for DATALOG2 acquisition? Also, does DATALOG2 support timestamping GPIO/EXTI events so they can be synchronized with the vibration data stream?

[Jhon bruce]

Using the onboard RS485 interface as an alternative trigger input sounds like an interesting approach, especially with the expansion GPIOs already occupied. It would be helpful to know whether those pins can be repurposed as GPIO/EXTI inputs without affecting the RS485 functionality, and how DATALOG2 handles event timestamps during acquisition.

This STWIN.box documentation may also be useful when checking the available interfaces and pin configuration.

[Nandu6460]

My current idea is to connect the open-collector speed sensor to the STWIN.box through the RS485 terminal interface, using a voltage divider and appropriate pull-up circuitry to ensure the GPIO voltage remains within the 3.3 V limits of the STM32.