# Achieving 240+ FPS with Frame-Synchronized Multi-Source Tracking (N6/PAG7936)

**URL:** <https://forums.openmv.io/t/achieving-240-fps-with-frame-synchronized-multi-source-tracking-n6-pag7936/11542>\
**Category:** OpenMV Boards\
**Created:** [March 11, 2026, 9:25am UTC](https://forums.openmv.io/t/achieving-240-fps-with-frame-synchronized-multi-source-tracking-n6-pag7936/11542 "2026-03-11T09:25:51Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![nelson](https://avatars.discourse-cdn.com/v4/letter/n/dec6dc/32.png) [@nelson](https://forums.openmv.io/u/nelson)\
**Post date:** [March 11, 2026, 9:25am UTC](https://forums.openmv.io/t/achieving-240-fps-with-frame-synchronized-multi-source-tracking-n6-pag7936/11542/1 "2026-03-11T09:25:51Z")

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Hi OpenMV Team,

I am working on a high-speed spot tracking system using the **OpenMV N6** with the **PAG7936** sensor. I need to synchronize external light sources (via GPIO) with the camera’s exposure window to ensure each frame only captures specific light spots without cross-talk.

- **Continuous Mode:** ~470 FPS (QVGA)
- **Triggered Mode (`csi.IOCTL_SET_TRIGGERED_MODE`):** Drops to ~180 FPS (Raw capture)  
[Add support for triggering.](https://github.com/openmv/openmv/pull/2564)
- **Actual System (with `find_blobs` & UART):** ~110 FPS
- **Target:**  **240+ FPS**

Proposed Schemes:

**Scheme A: Triggered Mode Optimization** The `snapshot()` call in triggered mode seems to have a large software overhead. Is there any low-level `ioctl` or driver tweak to reduce the trigger-to-capture latency to reach 240+ FPS?

**Scheme B: External Sync with Frame Indexing** If we run in Continuous Mode (400+ FPS) and use an external MCU to pulse lights via **FSYNC (P10)**:

- Is there a way for the Python script to read a **Hardware Frame Count** or DMA tag to ensure the `snapshot()` buffer aligns with the correct external light phase?

**Scheme C: Hardware Windowing (ROI)** Does the N6 driver support hardware-level cropping/windowing (e.g., to **QQVGA 160x120** ) to increase the readout speed?

**Scheme D: Asynchronous Processing & Task Pipelining**

- **Background DMA:** Does the CSI driver support **Double Buffering / Background DMA**? We want to expose the next frame while the CPU is processing the current one.

- **Task Pipelining (UART & CPU):** Currently, `find_blobs` and UART communication are executed sequentially. Is there a way to offload the UART transmission to DMA or a separate thread (without blocking the CPU) so that the next `find_blobs` can start immediately?

- **N6 NPU Offloading:** Can the **N6’s internal NPU** be leveraged to offload basic image tasks like blob detection? This would significantly free up the CPU for protocol handling and system logic.

We prioritize speed and deterministic frame-to-light alignment. Which of these approaches would you recommend for achieving 240+ FPS?

Thanks!

```auto
import csi, time
from machine import Pin

csi0 = csi.CSI()
csi0.reset()
csi0.pixformat(csi.GRAYSCALE)
csi0.framesize(csi.QVGA)
csi0.auto_exposure(False, exposure_us=2000)
csi0.framerate(470)
csi0.snapshot(time=2000)

csi0.ioctl(csi.IOCTL_SET_TRIGGERED_MODE, True)
pins = [Pin("P0", Pin.OUT_PP), Pin("P1", Pin.OUT_PP)]

frame_count = 0
clock = time.clock()

while True:
    clock.tick()
    target_idx = frame_count % 2

    pins[target_idx].high() # turn on LED

    img = csi0.snapshot()

    pins[target_idx].low() # turn off LED

    # Processing & Communication (Takes ~5ms)
    # blobs = img.find_blobs(...)
    # uart.write(...)

    frame_count += 1
    if frame_count % 100 == 0:
        print(clock.fps())

```

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<div class="post-metadata">

**Author:** ![kwagyeman](https://yyz1.discourse-cdn.com/flex029/user_avatar/forums.openmv.io/kwagyeman/32/4_2.png) [@kwagyeman](https://forums.openmv.io/u/kwagyeman)\
**Post date:** [March 11, 2026, 9:29am UTC](https://forums.openmv.io/t/achieving-240-fps-with-frame-synchronized-multi-source-tracking-n6-pag7936/11542/2 "2026-03-11T09:29:56Z")

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Please keep the topic in the PR. There’s no need to make a forum post for this.

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<div class="post-metadata">

**Author:** ![kwagyeman](https://yyz1.discourse-cdn.com/flex029/user_avatar/forums.openmv.io/kwagyeman/32/4_2.png) [@kwagyeman](https://forums.openmv.io/u/kwagyeman)\
**Post date:** [March 11, 2026, 9:31am UTC](https://forums.openmv.io/t/achieving-240-fps-with-frame-synchronized-multi-source-tracking-n6-pag7936/11542/3 "2026-03-11T09:31:14Z")

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