User's Manual

Serial Port Operation

The 24XStream modules come equipped with a CMOS-level asynchronous serial port. Through

this serial port, the 24XStream can communicate directly with any device having a UART

interface, or with a PC, or other RS-232 port, via the MaxStream interface board. By connecting

the 24XStream to a host device’s serial port, the host device becomes empowered to

communicate wirelessly with ease. To transmit, the host device simply sends serial data to the

24XStream and the 24XStream converts the data to spread spectrum FCC-approved wireless data.

When this spread spectrum data is detected by the receiving 24XStream module, the data is

checked for integrity and then sent to a receiving device via the serial port. This is shown in

Figure 3 below.

Figure 3 – Diagram of data flow from a microcontroller or PC (or any RS-232 device) through a pair

of 24XStream wireless modules to receiving microcontroller or PC. (Note: When connecting the

24XStream to an RS-232 device, the MaxStream Interface Board adjusts voltage levels between the

RS-232 device and the MaxStream wireless module.)

Serial Pins

Figure 3 above shows 4 data lines needed to interface from a microcontroller or RS-232 device to

the 24XStream modules. These four lines represent DI (Data In), DO (Data Out), *CTS, and

RTS/CMD (request to send/command mode). (All low-asserted pins are distinguished with a line

over the top of the pin name, or a ‘*’ symbol prefacing the pin name.) While the DI and DO pins

are indispensable in almost all cases, the *CTS and RTS/CMD may not be needed under certain

conditions. The following includes a brief description of each of these pins and under what

conditions the pins must be used. A brief explanation of the *CONFIG pin is also provided.

DI (Data In) – Pin 4 (Input)