EVM-915-DTS-BZS Linx Technologies, EVM-915-DTS-BZS Datasheet - Page 7

• Manufacturer Part Number: EVM-915-DTS-BZS
• Description: RF Development Tools 915 MHz Wireless Module DTS Brazil
• Manufacturer: Linx Technologies
• Type: Wi-Fir

Specifications of EVM-915-DTS-BZS

• Rohs: yes
• Product: Evaluation Modules
• Tool Is For Evaluation Of: Wi.232DTSB-R
• Frequency: 915 MHz
• Operating Supply Voltage: 3 V to 3.6 V
• Interface Type: UART
• Factory Pack Quantity: 1

The module is designed to interface directly to a host UART. Three signals
are used to transfer data between the module and the host UART: TXD,
RXD and CTS. TXD is the data output from the module. RXD is the data
input to the module. CTS data output indicates the status of the module’s
data interface. If CTS is low, the module is ready to accept data. If CTS is
high, the module is busy and the host UART should not send any further
data.
Internally, the module has a 192 byte buffer for incoming characters from
the host UART. The module can be programmed to automatically transmit
The module has a UART-type serial interface and contains special
application software to create a transparent UART-to-antenna wireless
solution capable of direct wire replacement in most embedded
RS-232/422/485 applications.
Preliminary Draft
Note:
communications required by RS-232, RS-422, and RS-485 networks,
it is not compatible with the electrical interfaces for these types of
networks. The module has CMOS inputs and outputs and would
require an appropriate converter for the particular type of network it is
connected to.
Figure 8: Wi.232DTS Networking Concept
Although the module is capable of supporting the typical serial
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when the buffer reaches a programmed limit, set by regUARTMTU. The
module can also be programmed to transmit based on a delay between
characters, set by regTXTO (set in 1mSec increments). These registers
allow the designer to optimize performance of the module for fixed length
and variable length data. The module will support streaming data, as well.
To optimize the module for streaming data, regUARTMTU should be set to
144, and regTXTO should be set to a value greater than 1 byte time at the
current UART data rate. If the buffer gets full, or the timer set by regTXTO
expires, while the module is still in the process of sending the previous
packet over the RF link, the module will assert CTS high, indicating that the
host should not send any more data. Data sent by the host while CTS is
high will be lost.
When the MAC layer has a packet to send, it will use a carrier-sense-mul-
tiple-access (CSMA) protocol to determine if another module is already
transmitting. If another module is transmitting, the module will receive that
data before attempting to transmit its data again. If, during this process, the
UART receive buffer gets full, the CTS line will go high to prevent the host
UART from over-running the receive buffer. The CSMA mechanism intro-
duces a variable delay to the transmission channel. This delay is the sum of
a random period and a weighted period that is dependent on the number
of times that the module has tried and failed to acquire the channel. For
applications that guarantee that only one module will be transmitting at any
given time, the CSMA mechanism can be turned off to avoid this delay.
The MAC layer prefixes the data with a packet header and postfixes the
data with a 16-bit CRC. The 16-bit CRC error checking can be disabled to
allow the application to do its own error checking. Data is encoded using a
proprietary algorithm (DirectSPREAD™) to spread the RF energy within the
transmission bandwidth.
Modules can operate in groups. Each module can be assigned an 8-bit
group ID, which is used to logically link it to other modules on the same
channel. All modules on a channel will interoperate, regardless of their re-
spective group IDs. In other words, the CSMA mechanism will prevent colli-
sions of modules on the same channel but belonging to different groups.
Modules can also operate in two network modes: Master/Slave and Peer-
to-Peer. These modes define a set of communication rules that identi-
fies which modules can talk to any given module. In Master/Slave mode,
masters can talk to slaves and other masters, slaves can talk to masters,
but slaves cannot talk to other slaves. This mode is sometimes required
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Preliminary Draft