Build fully IoT board

Hey everyone,

With some friends we made some connected devices which used only WiFi. The WiFi-only was a good way to start prototyping but now, we need to make it more indistrual and as small as possible.
By the way I'm using Fritzing and Eagle to build our own electronic board which must not exceed the size of a credit card. This one must have:

  • GPRS module
  • Sigfox/LoRa module
  • WiFi module

To start I choose to use the ATMEGA328 (tqfp) which is very small and seems to be enough powerfull for our devices usage.
My problems are:

How to use the three modules on the same board but not at the same time because they all use UART protocol ?
For this problem I thought to put a microcontroller which will have a firmware which will disable the other modules (e.g: If I use the WiFi, a transistor will open the UART circuits of the SigFox and GPRS module.)
Also, may there is a microcontroller which have multiple UART pins (like the ATMEGA2056 on the Arduino Mega)

Except for the WiFi which will be supply by the ESP8266 which is kind of small, I didn't found the other modules (GPRS and Sigfox/LoRa) in small size. This is always shield or big extern board. Do you have some advices for this problem ?

Hope you understood me,
Thank you for any help.

Have a good day guys!



Up where?