Rainbow Electronics DAB-WLS-C01 (WiFi) - Manual (Page 11)

7. Functional Description
The Wireless LAN module is a self-contained product and requires only power to implement full
communication. The integrated, high performance antenna together with the RF and baseband circuitry
provides the Wireless LAN connectivity and the UART interface for a connection to a host system.
The complexity and flexibility of configuration are made simple for the design engineer by the
integration of an extremely comprehensive scripting language - UWScript. UWScript provides a simple
BASIC style language with a rich library of built-in functions that simplify connection of the module.
7.1 Interfaces
7.1.1 UART interface
Modem signal nomenclature can be a source of great confusion, particularly on devices which can be
configured in either DCE (Data Communications Equipment) or DTE (Data Terminal Equipment) format.
For the purpose of this data sheet all UART signals are defined on the assumption that the module is
being used as a conventional DCE. I.e it is behaving like a serial PSTN modem.
UART_TX, UART_RX, UART_RTS and UART_CTS form a conventional asynchronous serial data port with
handshaking, conforming to the ITU-T v.24 standard for DCE signalling. The interface is designed to
operate correctly when connected to other UART devices such as a 16550A. Note that the signalling
levels are a nominal 0V and 3.0V and are inverted with respect to the signalling on an RS232 cable.
The interface is programmable over a variety of baud rates, with no, even or odd parity, one or two
stop bits and hardware flow control. Non-standard baud rates are supported – for more information
please contact EZURiO. Auto-bauding is not supported.
On power-up the UART defaults to 115200,n,8,1.
Note that there is no standardisation regarding the nomenclature of RX and TX across a DCE-DTE
interface. Some implementations show TX(DCE) connected to TX(DTE) to give naming consistency
across a cable, whereas other show TX driving RX to reflect logical port directions. Always check the
direction of ports on DCE and DTE.
In a DCE mode, where the module is being driven as a peripheral by a host processor application, the
UART signals should be connected according to the following scheme:
Port UART_TX transmits data to the application’s /RXD input.
Port UART_RX receives data from the application’s /TXD output.
Two-way hardware flow control is implemented by UART_RTS and UART_CTS. In DCE mode, UART_RTS
is an OUTPUT and is active low. UART_CTS is an INPUT and is active low. These signals operate
according to normal industry convention.
Some serial implementations link UART_CTS and UART_RTS to remove the need for handshaking.
EZURiO does not recommend linking UART_CTS and UART_RTS other than for testing and prototyping.
If these pins are linked and the host sends data at the point that the Wireless Module deasserts its
UART_RTS signal, then there is a significant risk that internal receive buffers will overflow which could
lead to a loss of data. EZURiO recommend that the correct UART_CTS to UART_RTS handshaking
protocol be adhered to in order to ensure proper operation.
DSH_WISMC01_1v2 WISM 40 pin TCP-IP Data Sheet.doc © 2007 EZURiO Ltd
Page 11