# M0155 GPIO 109 Sync Output and IR/EO Camera Synchronization

Source: https://forum.modalai.com/topic/5536/m0155-gpio-109-sync-output-and-ir-eo-camera-synchronization
Category: VOXL 2 and VOXL 2 Mini (https://forum.modalai.com/category/26/voxl-2-and-voxl-2-mini)
Posted: 2026-11-03 07:36:00 UTC by 김다연
Replies: 1 · Views: 40

## 김다연 · 2026-11-03 07:36:00 UTC

**Hardware:** (board / drone / SKU, serial # if you have it): voxl2

**Software version:** (paste the output of `voxl-version`)

**Configuration / services:** (paste the output of `voxl-inspect-services`)

**What I am trying to do:**
1. When the M0155 board is connected to VOXL 2, is GPIO 109 enabled to output a 30 Hz sync signal, as it is with the M0173 board?
2. If we connect IR and EO cameras to the J6 and J7 connectors on VOXL 2 through the M0155 board, will the cameras be synchronized automatically, or are software configuration changes required?

**What actually happens:** (error messages, behavior)

**Steps to reproduce:**

**Logs / pictures:** (attach files; PX4 logs -> https://logs.px4.io)

## Reply by Vinny (ModalAI staff) · 2026-11-03 22:47:17 UTC

Hi @김다연 
1. GPIO 109 sync through M0155

Yes. GPIO 109 is on pin 26 of J6, J7 and J8, and M0155 passes it through to the sensor. Same sync signal M0173 uses. It is driven by voxl-fsync-mod.

2. IR + EO on J6 and J7

Not automatic. Two things are required in software. The sensors must be running a sensor module built with sync input enabled (the _fsin_ variants under /usr/share/modalai/chi-cdk/, selected by camera HW ID), and voxl-fsync-mod must be enabled and configured for the correct GPIO. Without the fsin sensor module, the sensor ignores the trigger and free-runs.

The fsync period also sets the frame rate, which is the cleaner answer to your earlier 8.6 fps question: drive the rate from voxl-fsync-mod rather than adding a sensor mode to the driver.