MaxStream 9XCite XC09-009 Series, Руководство по эксплуатации продукта

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Datasheet of XC09-009-DK - KIT DEV FOR 900MHZ 9600BPS 1MW
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9XCite™ OEM RF Module – Product Manual v2.1 [2007.01.04]
© 2007 MaxStream, Inc. 9
2.1.3. Serial Data
Data enters the MaxStream RF module through the DI Pin 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) needed for communication. Serial
communication consists of two UARTs which must be 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 modem.
Figure 2 ‐ 03. Serial (UART) data packet 0x1F (decimal ʺ 31 ʺ ) as transmitted through the XCite Module
Data Format is 8 ‐ N ‐ 1 (8 bits ‐ No Parity ‐ 1 Stop Bit)
In the example above, the MaxStream RF module transfer 8 bits over-the-air [Selectable using BI
(Number of Bits) Parameter]. Start and stop bits of the UART signal are not transmitted over-the-
air, but are regenerated by the receiving modem.
The MaxStream OEM RF Modules support the following data formats [See NB (Parity) Parameter]:
• 8-none-1, 7-any-1
• 8-even-1
• 8-odd-1
• 8-mark-1, 8-none-2
• 8-space-1
DI (Data In) Buffer
Once serial data has entered the 9XCite Module through the Data In (DI) Pin, the data is stored in
the DI Buffer until it can be transmitted.
Once the first byte of data enters the DI Buffer, the module begins to initialize the RF channel
(unless RF data is being received). In the case where the module is receiving RF data, the serial
(UART) data is stored in the DI Buffer. When the DI Buffer has only 17 bytes of memory left, the
XCite Module de-asserts (high) CTS to signal to the host device to stop sending data. CTS re-
asserts once the DI Buffer has at least 35 bytes available in memory. Once in the DI Buffer, the
data is packetized for transmission.
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