GSM/LTE

daneduplooy · January 14, 2020, 12:20pm

Hi

I am busy researching hardware options for a new project, and the OpenMV boards look like they could work well. One of the project requirements however is LTE connectivity - how difficult (/ possible) would it be to get an OpenMV board connected via LTE?

Thank You

iabdalkader · January 14, 2020, 2:47pm

If the LTE module has a serial/i2c/spi port it should work just fine.

daneduplooy · January 14, 2020, 7:14pm

Thanks for the reply. Any pointers on how to go about getting this working please - library(s) etc?

kwagyeman · January 14, 2020, 8:22pm

Since we are a MicroPython board please Google for a MicroPython driver for a popular cellular modem. Someone has likely made an open source one. Otherwise, you have to write your own.

darrask · May 30, 2021, 2:34pm

Hi there, we are also interested in this for our own project, are there any updates on this, @daneduplooy ?

JeanJean · June 16, 2021, 9:32am

I do have the same question.
For my hardware design I have chosen an SIM7020C NB-IoT module connected via UART to the STM32.
But I still need to write/find a driver for it.
I “simply” want to transfer an captured image to the cloud

Stub · June 16, 2021, 9:52am

Hi, I use the OpenMV wifi module and a 4G router. Since the driver already exists for that and it will be easy to upgrade to 5G whenever the routers come along. Please let me know if you want details of the 4G kit.

xwb · July 16, 2021, 2:50am

@Stub yes please do share! I am struggling with the same issue. Thanks!

xwb · July 16, 2021, 2:50am

@JeanJean Any updates? I am looking at using a SIM7xxx module to. Is it working? Thanks!

Stub · July 17, 2021, 9:44pm

Hi,

I use a TP-link TL-MR3020 with a Huwawei 4G USB modem and a ‘3’ data only SIM in the UK, as it is small and low power consumption, but any 4G wifi router for your country should work.

MoZen · August 10, 2021, 1:53am

Hi all,

I want to test Sara-R4 modem as an LTE shield for OpenMV, I found some libraries in u-Blox documentation, but they are in C language, not Python as far as I know, unfortunately;

Looking at Micropython libraries, it looks like Micropython also uses C files, but I am not sure how. Should I use STM32Cube software for that? Do you use software to converts C (.h files) to .py files for OpenMV?

If we wanna add an LTE modem to ESP32 using these u-Blox C files, It looks more straightforward as ESP32 use C libraries too;

However, I am not sure how to use these C files as an LTE modem library in Micropython-based boards like OpenMV. How can I leverage STM32 C files written for the u-Blox modem in OpenMV?

Thanks,
MoZen

MoZen · August 10, 2021, 2:16am

Searching in the forum, based on Kwabena, all methods are written in C in src/omv/imlib directory.

So the question is how to use ublox sara-r4 C files I linked in my previous message?
How to use it to communicate from OpenMV to ublox-sara-r410 LTE modem?
I know how to import a module, but I do not know how you call a method that is written in C in Python program…

For example, in Pycom Gpy they have a network model and they import LTE functionality from it;

from network import LTE
lte = LTE()

How can we add this functionality to OpenMV?
Let’s Suppose that on the hardware side, we use Uart; TX, RX and GND to communicate between Sara-r4 and OpenMV. (In reality, it needs some level shifting too).

Thanks,
Mohsen

iabdalkader · August 12, 2021, 12:27am

You’ll need to write your own MicroPython module, lucky for you this is much easier now with recent changes, here’s an example module (note it’s not enabled by default):

github.com

openmv/openmv/blob/master/src/omv/modules/examplemodule.c

// Include MicroPython API.
#include "py/runtime.h"

// This is the function which will be called from Python as cexample.add_ints(a, b).
STATIC mp_obj_t example_add_ints(mp_obj_t a_obj, mp_obj_t b_obj) {
    // Extract the ints from the micropython input objects.
    int a = mp_obj_get_int(a_obj);
    int b = mp_obj_get_int(b_obj);

    // Calculate the addition and convert to MicroPython object.
    return mp_obj_new_int(a + b);
}
// Define a Python reference to the function above.
STATIC MP_DEFINE_CONST_FUN_OBJ_2(example_add_ints_obj, example_add_ints);

// Define all properties of the module.
// Table entries are key/value pairs of the attribute name (a string)
// and the MicroPython object reference.
// All identifiers and strings are written as MP_QSTR_xxx and will be
// optimized to word-sized integers by the build system (interned strings).

This file has been truncated. show original

JeanJean · September 7, 2021, 9:35am

@MoZen: I want to do the same, but for SIM7020, but still haven’t got the time to work on the implementation itself.
Maybe we can collaborate on this, give me a PM.