UART + non-connectable advertisement

I am trying to broadcast a non-connectable advertisement (such as a beacon) while I am connected to a device that I am transferring data via TX. I am working with a nRF52840 on Segger Embedded Studio v3.4 with the nRF5_SDK_15 as the base for my code manipulation. More specifically I'm going off the ble_app_uart example for pca10040 s132. I don't care about receiving data through RX from the device I am connected to. By the way, I have tried using the Time Slot API where I try to initiate the advertising of the beacon when the device connects through UART. It is my understanding from projects such as the nRF51-multi-role-protocol-conn-observer-advertiser example on github but this is for nrf51 devices. I have tried to mimick this project as well as articles showing how the time slot api can be used to implement non-connectable advertising during a connection as a peripheral. I have also tried doing this without the Time Slot API but to no avail. My thinking is that the buffer transferring data out of the device can only handle 31 bytes of data per interval, but both the advertising and uart protocols take up 31 bytes so its not possible to do at the same time. There must be a way to switch between the two protocols (uart and advertisement) when the radio interrupt occurs. Please help.