# Introduction

Although this library’s expected primary use case is with the SEGGER RTT technology through the SDK’s RTT Viewer, you can also use the library with UART simply by linking to a different library variant. There are four library variants that can be selected between without changing the underlying code:

- RTT variants include both blocking and non-blocking debug.
- UART variants include support for DMA and user defined pins for UART, TX and RX, where both variants are non-blocking.

NOTE: The TX circular buffer used for UART printing has a 512-character limit. If more characters are queued up before the buffer is flushed, the characters exceeding the buffer limit are dropped.