ESP32-S3 + OV5640: RGB565 works, but JPEG fails during Camera() initialization

[Prototype0S]

Hi! I'm trying to use an OV5640 camera with an ESP32-S3 WROOM N16R8 using the micropython-camera-API.

I'm using the precompiled firmware:

mpy_cam-v1.27.0-ESP32_GENERIC_S3-SPIRAM_OCT

MicroPython reports:
MicroPython v1.27.0-dirty on 2026-01-12
ESP32S3 Generic ESP32S3 module with Octal-SPIRAM

The board has 16 MB flash and 8 MB PSRAM. esp.flash_size() reports:16777216

I can initialize and capture from the OV5640 reliably using RGB565 at QQVGA.

This configuration works:

python
from camera import Camera, PixelFormat, FrameSize

cam = Camera(
data_pins=[11, 9, 8, 10, 12, 18, 17, 16],
vsync_pin=6,
href_pin=7,
sda_pin=4,
scl_pin=5,
pclk_pin=13,
xclk_pin=15,
xclk_freq=20000000,
powerdown_pin=-1,
reset_pin=-1,
pixel_format=PixelFormat.RGB565,
frame_size=FrameSize.QQVGA
)

It reports:
Sensor: OV5640
Pixel format: 0
Frame size: 1
Width: 160
Height: 120
Quality: 85
Grab mode: 1
FB count: 2

RGB565 capture is stable at roughly 20 FPS.

However, if I change only:

python
pixel_format=PixelFormat.RGB565

to:

python
pixel_format=PixelFormat.JPEG

the constructor fails with:

text
OSError: Failed to capture initial frame. Construct a new object with appropriate configuration.

I've also tried:

• JPEG + QQVGA
• JPEG + QVGA
• GrabMode.LATEST
• GrabMode.WHEN_EMPTY
• explicitly setting jpeg_quality=85/90
• explicitly setting fb_count=2
• using the defaults
• reconfigure(pixel_format=PixelFormat.JPEG, ...)` after successfully initializing RGB565

With reconfigure(), the pixel format changes to JPEG successfully, but frame_available() remains false and capture() returns None.

The failure therefore appears to be specifically related to JPEG frame acquisition with this OV5640/ESP32-S3 combination, rather than the pin configuration or basic camera initialization.

My camera module contains:

['class', 'name', 'Camera', 'FrameSize',
'GainCeiling', 'GrabMode', 'PixelFormat', 'dict']

There is no camera.Version() in this build.

My questions

1. Is JPEG capture from an OV5640 expected to work with mpy_cam-v1.27.0-ESP32_GENERIC_S3-SPIRAM_OCT?
2. Is there a known issue with OV5640 + ESP32-S3 + JPEG** in this firmware/driver version?
3. If so, is there a different firmware build or version I should use?
4. Is there a particular OV5640 configuration/register setting required for JPEG mode that isn't being applied by the MicroPython API?
5. Would you recommend building the firmware from source with a newer/different esp32-camera version?

I'm happy to provide any additional logs or test results.

Thanks!