Suggestion for part selection of embedded IoT project

Hi Ravi,

I am working on one project where i need to have multiple internet network like Ethernet,WIFI and LTE.

Can you help me to find right parts?

My idea is to have complete modular design where main pcb can accept ether LTE (SIM7000) pluggable module or (Ethernet+WIFI) pluggable module.

Ethernet and WIFI will be one single module. I tried to have this with Esp32. But Ethernet is not reliable and because of both network most of time device hang.

Then i planned to go with linux SBC, like Omega2 or Linkit Smart 7688.

Can you suggest me your approach for the problem statement?

Suman Kumar Jha


well here i can see that there is no application specified on where exactly your gonna use this whole device with multiple internet connections.

Nevertheless, i would suggest you to either use ESP32/ESP8266, with freeRtos. And for Ethernet you can use Wiznet Chips W5500/W5100.
And for GSM there are many modules out there like you said SIM7600/7000 you can use that too.

Now, you have inbuilt Wifi and Bluetooth too (If you use ESP32) , as well as Ethernet and Gsm Module too. so yeah, this should help you !

Parth Temkar

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My inputs would be the same as @ParthTemkar .
I would put a big 3x UART STM32 in the middle and make all the modules as slaves and rule them :slight_smile:

Thanks Parth, your design approach was my first option. But i faced lot of issue with esp32,

  1. in my design ethernet and sd card were on same SPI bus and firmware was written to read one set of Data and send to server and then come back to read again from SD card.
  2. On field when power or internet goes off (from ISP side) and it come back then esp32 couldn’t able reinit DHCP in many cases.

Its good for hobby project. I am looking something reliable approach.

Thanks Ravi, can you suggest any STM32 MCU with Ethernet PHY and WIFI RF built in.

I want Ethernet and WIFI driver should be handled at inner level of hardware.

Please response soon


Well, till you code the esp32 with the arduino yes its gonna be unstable, but i have deployed it to multiple places and it works like a charm. for every problem your facing the simple solution would be to reset the esp with a help of external watchdog or anything. nevertheless, in terms of chosing the stm32, well the provides a hell lot of options to chose from which would be a convenient option for you. but id recommend you stm32F4 i guess it has the phy, or even stm32F3 or Stm32G0 just go and check in the product selector.

and sorry to ruin your excitement but unfortunately stm doesn’t provide a WiFi RF based Mcu at all, even i’m struggling with the same to figure out. so i ended up using the Texas Instrument’s CCxxxx based Wifi Modules. there is even this product SensiboSky , it has a STM32F0 in combination with CC3100, and it even has the abilities to do OTA updates !

So, This would be a better industrial combination for you STM32 + Texas’s WiFi Chips + Supporting Hardware

And i guess mr. Ravi would have been asleep by now so i thought to reply instead of him. Hope it was Helpful

Parth Temkar

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Thanks Parth,
I tried to use ESP IDF, but found difficult.
I want to learn ESP32 IDF, but from where i should start.

From last few weeks i was working on Omega2/Linkit Smart 7688. These small Linux SBC seems comfortable. It can handle both ethernet and Wifi. I did small test for mqtt with ssl. All Ok

Till now not started main program, here its python language. Work is in progress, taking too much time

I don’t know i am on right path or not

Well the path depends on what end result your expecting , and switching from a microcontroller to microprocessor that’s a big step no doubt. But then you need to stick to one… and look for “pcbreflux” on YouTube for esp32 tutorials.

And yes you can always work with omega2, raspberry pi zero, orange pi and so on. But remember they become a single board computers and where “C” would be supported in these, but it’s on python where you will find more resources. So now it’s in your hands to select the proper candidate for your job!

Parth Temkar

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