How to send an image across serial port and not interrupt other output or kill frame rate?

Plaba · March 8, 2021, 6:27pm

Hello! I’m rather new to OpenMV, and I’m writing a Java application that connects to the OpenMV by a serial port.

I noticed that the OpenMV IDE was capable of receiving both the frames that the OpenMV captured, and at the same time receiving the uninterrupted output of the program. What would I need to do to replicate that behavior between a Java application and the OpenMV?

iabdalkader · March 8, 2021, 6:27pm

You need to port this:

github.com

openmv/openmv/blob/master/tools/pyopenmv.py

#!/usr/bin/env python2
# This file is part of the OpenMV project.
#
# Copyright (c) 2013-2021 Ibrahim Abdelkader <iabdalkader@openmv.io>
# Copyright (c) 2013-2021 Kwabena W. Agyeman <kwagyeman@openmv.io>
#
# This work is licensed under the MIT license, see the file LICENSE for details.
#
# Openmv module.

import struct
import sys,time
import serial
import platform
import numpy as np
from PIL import Image

__serial = None
__FB_HDR_SIZE   =12

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And there’s an example that uses that module to execute a script and read the framebuffer:

github.com

openmv/openmv/blob/master/tools/pyopenmv_fb.py

#!/usr/bin/env python2
# This file is part of the OpenMV project.
#
# Copyright (c) 2013-2021 Ibrahim Abdelkader <iabdalkader@openmv.io>
# Copyright (c) 2013-2021 Kwabena W. Agyeman <kwagyeman@openmv.io>
#
# This work is licensed under the MIT license, see the file LICENSE for details.
#
# An example script using pyopenmv to grab the framebuffer.

import sys
import numpy as np
import pygame
import pyopenmv
from time import sleep

script = """
# Hello World Example
#
# Welcome to the OpenMV IDE! Click on the green run arrow button below to run the script!

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Plaba · March 8, 2021, 6:27pm

Thanks for your reply!

I’ve already ported the script to Java. It’s available at GitHub - entech281/JOpenMV: Java code to manage an OpenMV camera..

My problem is that I need to use the serial port for other data as well. What would I need to do not have the frame data and the other data print at the same time and get mixed together?

kwagyeman · March 8, 2021, 6:27pm

Hi, this uses the debug mode so they are already not mixed.

Plaba · March 8, 2021, 6:27pm

Thanks a lot!

After a little digging, I figured out that I need to use the tx_buf API call to read the output of the program.

Thanks for your help!

iabdalkader · March 8, 2021, 6:27pm

Yes that’s right, you just need the tx_buf_len and tx_buf commands.