User's Manual

Parity None, Odd, Even

Number of stop bits 1 or 2

Bits per channel 8

Figure 8: Possible UART settings

The UART interface is capable of resetting WT12 upon reception of a break signal. A Break

is identified by a continuous logic low (0V) on the UART_RX terminal, as shown in Figure

below If t

BRK

is longer than the value, defined by the PS Key

PSKEY_HOST_IO_UART_RESET_TIMEOUT, (0x1a4), a reset will occur. This feature allows

a host to initialize the system to a known state. Also, WT12 can emit a Break character

that may be used to wake the Host.

BRK

UART_RX

Figure 9: Break signal

Note

The DFU boot loader must be loaded into the Flash device before the UART or USB

interfaces can be used. This initial flash programming can be done via the SPI.

Table 15 shows a list of commonly used Baud rates and their associated values for the

Persistent Store Key PSKEY_UART_BAUD_RATE (0x204). There is no requirement to use

these standard values. Any Baud rate within the supported range can be set in the

Persistent Store Key according to the formula in Equation below.

Baud Rate =

PSKEY_UART_BAUD_RATE

0.004096

Figure 10: Baud rate calculation formula