EZ F411 1S-2S AIO only has 2 UARTs available, UART1 is for smart audio by default and UART2 is for setting up the receiver. If you want to add the GPS on the EZ board while enabling SmartAudio and setting up the receiver, then you could set up the GPS using softserial.
What's softserial? You can find out more info on the Oscarliang and Multirotorguide tutorial.
In this tutorial, we will walk you through how to set up a GPS on the softserial on EZ board.
In general, we split the UART1 for SmartAudio and GPS.
UART1 TX pin is for SmartAudio and we will make UART1 RX pin as softserial to set up GPS.
How to configure softserial port?
1. Firstly, we should enable the "softserial" in the Configuration tab in Betaflight.
2. Then, we need to find out the output pin name for UART1 RX,
Type "resource" command in CLI. We can find out that A10 is the output pin name for UART1 RX.
3. Next, we should free the UART1 RX pin so as to reassign it to softserial.
Type "resource SERIAL_RX 1 none" in CLI
4. After freeing the resource, we can finally reassign A10 pin to the softserial in the CLI.
Type "resource SERIAL_RX11 A10" and don't forget to type "save" in the CLI to save the settings.
FYI: "11" stands for softserial 1
5. Finally, after all of those commands and reassigning, we can go to "Ports" tab in Betaflight, and we can see the "SOFTSERIAL" show up there. we can enable "GPS" in "SOFTSERIAL" tab and "VTX (TBS Smart Audio)" in "UART1" tab.