XStream™OEMRFModule–ProductManualv5.x00[2006.02.24]
2. RFModuleOperation
2.1. Serial Communications
The XStream OEM RF Module interfaces to a host device through a CMOS-level asynchronous
serial port. Through its serial port, the module can communicate with any UART voltage
compatible device or through a level translator to any RS-232/485/422 device.
2.1.1. UART-Interfaced Data Flow
Devices that have a UART interface can connect directly through the pins of the XStream Module
as is shown in the figure below.
Figure2‐01. SystemDataFlowDiagraminaUART‐interfacedenvironment
(Low‐assertedsignalsdistinguishedwithhorizontallineoversignalname.)
Serial Data
Data enters the XStream Module through the DI pin (pin 4) as an asynchronous serial signal. The
signal should idle high when no data is being transmitted.
The UART performs tasks, such as timing and parity checking, that are needed for data
communications. Serial communication consists of two UARTs configured with compatible
parameters (baud rate, parity, start bits, stop bits, data bits) to have successful communication.
Each data packet consists of a start bit (low), 8 data bits (least significant bit first) and a stop bit
(high). The following figure illustrates the serial bit pattern of data passing through the module.
Figure2‐02. UARTdatapacket0x1F(decimalnumber“31”)astransmittedthroughtheXStreamModule
ExampleDataFormatis8‐N‐1(bits–parity‐#ofstopbits)
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