User's Manual

Bluegiga Technologies Oy
Page 17 of 40
6 UART Interface
This is a standard UART interface for communicating with other serial devices.WT11i UART interface provides
a simple mechanism for communicating with other serial devices using the RS232 protocol.
Four signals are used to implement the UART function. When WT11i is connected to another digital device,
UART_RX and UART_TX transfer data between the two devices. The remaining two signals, UART_CTS and
UART_RTS, can be used to implement RS232 hardware flow control where both are active low indicators. All
UART connections are implemented using CMOS technology and have signalling levels of 0V and VDD.
UART configuration parameters, such as data rate and packet format, are set using WT11i software.
Note:
In order to communicate with the UART at its maximum data rate using a standard PC, an accelerated serial
port adapter card is required for the PC.
Table 10: Possible UART Settings
The UART interface is capable of resetting WT11i 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 9. If tBRK is longer than the value,
defined by PSKEY_HOST_IO_UART_RESET_TIMEOUT, (0x1a4), a reset will occur. This feature allows a
host to initialise the system to a known state. Also, WT11i can emit a break character that may be used to
wake the host.
Figure 9: Break Signal
Table 11 shows a list of commonly used data rates and their associated values for
PSKEY_UART_BAUD_RATE (0x204). There is no requirement to use these standard values. Any data rate
within the supported range can be set in the PS Key according to the formula in Equation 1