<![CDATA[Seeking for a specific unit, .. any ideas]]>Hi, In order to streamline our IOT equipment portfolio, I am seeking for a module that combines :
1] ESP 32 with WiFi
2] A mobile connection for MQTT (for example a SIM76 family)
3] Two Serial ports available : Serial1 and Serial2

This one looks great : IoT Base CatM but it seems that 1 Serial is used by the SIM module.
The same appear to go for this module : Atom DTU NBIoT2

Any suggestions how to combine a SIM76 family (or any other mobile chip), with the availability of Serial1 and Serial2?
Thanks for your creativity.

]]>https://community.m5stack.com/topic/8103/seeking-for-a-specific-unit-any-ideasRSS for NodeTue, 28 Apr 2026 23:06:53 GMTFri, 27 Feb 2026 07:52:25 GMT60<![CDATA[Reply to Seeking for a specific unit, .. any ideas on Sat, 07 Mar 2026 15:56:12 GMT]]>Hello @HappyUser

just curious, which SIM module did you settle on?

Thanks
Felix

]]>https://community.m5stack.com/post/30736https://community.m5stack.com/post/30736Sat, 07 Mar 2026 15:56:12 GMT<![CDATA[Reply to Seeking for a specific unit, .. any ideas on Fri, 06 Mar 2026 10:27:18 GMT]]>@felmue Thanks and sorry for my late response, been away.

yes , thanks for the reminder, we are ware of the difference and managed to find the best (at least what we think) SIM modules for our applications.
We prefer to stick to a few brands for ESP32, M5Stack is one of them, it might limit us, but it also challenges us to come up with solutions.

What we are testing now is using different serials by restarting the device ans select based on an identifier which port to use. Has some serious energy considerations, but it might turn out to be the best way because we can stick to preselected master devices (which inded limit #Serials). Regards

]]>https://community.m5stack.com/post/30722https://community.m5stack.com/post/30722Fri, 06 Mar 2026 10:27:18 GMT<![CDATA[Reply to Seeking for a specific unit, .. any ideas on Sun, 01 Mar 2026 15:52:17 GMT]]>Hello @HappyUser

ESP32P4 has 5 (five) UARTs. See here.

AFAIK all other ESP32 variants only have 3 (three) or less UARTs. (Of which the first one is used for debugging.)

Edit: ESP32S3 devices which have USB-C connected directly to the MCU (e.g. no dedicated USB-Serial chip) can use USB-C to debug (e.g. Serial) and still has 3 (three) UARTs free (e.g. Serial0, Serial1, Serial2).

Please find an example here.

BTW: are you aware of the fact that SIM76XXX is different from what is in IoT Base CatM (SIM7080G) and Atom DTU NBIoT2 (SIM7028)?

  • SIM76XXX uses LTE (which is different from NBIoT or LTE-M)
  • SIM7080G uses NBIoT or LTE-M
  • SIM7028 uses NBIoT only

Thanks
Felix

]]>https://community.m5stack.com/post/30701https://community.m5stack.com/post/30701Sun, 01 Mar 2026 15:52:17 GMT