The 3-wire UART topology requires only the following lines (see #SWAS0317491).

• RX
• TX
• nCTS

Figure 8-12 3-Wire UART Topology

Using 3-wire topology requires one of the following conditions to be met:

• Host always stays awake or active.
• Host goes to sleep, but the UART module has receiver start-edge detection for auto wake up and does not lose data.
• Host can always receive any amount of data transmitted by the SimpleLink device because there is no flow control in this direction.

Because there is no full flow control, the host cannot stop the SimpleLink device to send its data; thus, the following parameters must be carefully considered:

• Maximum baud rate
• RX character interrupt latency and low-level driver jitter buffer
• Time consumed by the user's application