–

–

–

–

12

The “Read Active Settings” button

at the bottom (Figure 16) reads the

existing configuration settings from the

module and adjusts the values in the

configuration sections based on the

module’s current configuration.

The right column in the window starts

with the Profile section (Figure 17).

Specific configuration settings can be

saved as a profile and loaded into a

connected module. This allows the

software to be used in small-scale

production lines for products that provide

connection to the CDI.

Select the “New” button to create a new profile and give it a name. Set

the configuration controls as desired and click the “Save” button to save

the profile. Click the “Program” button to send the profile to the module.

All of the profiles saved on the PC can be viewed in the drop down menu

and sent to the module with the “Program” button. The “Delete” button

removes the selected profile from the computer.

The Serial Command section (Figure 18)

provides the ability to send a specific

packet to the module. Byte values are

typed into the boxes to create the packet

and the “Send Command” button sends

the packet to the module. The ACK text

box displays the module’s response. The

possible values for each byte are shown

in the table below the “Send Command”

button.

The “Restore Defaults” button (Figure 19)

writes the factory default values to the

transceiver. This is an easy way to restore

the module to a known configuration.

13

Figure 16: Development Kit PC Software

Figure 17: Development Kit PC Software

Figure 18: Development Kit PC Software

Figure 19: Development Kit PC Software

Using the Boards as a Design Reference

From a layout perspective, the master development boards included in this

kit are quite simple, yet they illustrate some important techniques that can

be incorporated into a design. The module’s mounting pads extend slightly

past the edge of the part. This eases hand assembly and allows for better

heat conduction under the part if rework is necessary. The use of a full

ground plane fill on the lower side of the board serves three important

purposes.

First, since a ¼-wave antenna is employed, the ground plane is critical to

serve as a counterpoise. Application Note AN-00500 and AN-00501

provide additional details on how a ground plane affects antenna function.

Second, a ground plane suppresses the transfer of noise between stages

of a product as well as unintentional radiation of noise into free space.

Third, a ground plane allows for the implementation of a microstrip feed

to the antenna. The term microstrip refers to a PCB trace running over

a ground plane that is designed to serve as a 50-ohm transmission line

between the module and the antenna. A microstrip is implemented on this

evaluation board. The module’s data guide and a calculator available on the

Linx Technologies website provide more information on the microstrip

implementation and calculations.

About Antennas

The choice of antennas is one of the most critical and often overlooked

design considerations. The range, performance and legality of an RF link

are critically dependent upon the type of antenna employed. Linx offers a

variety of antenna styles that may be considered for a design. Included with

the development system is a Linx CW Series connectorized whip antenna

that should be connected prior to using the kit. Despite the fact that the

antenna is not centered on the board’s ground plane, it exhibits a VSWR of

<1.7 and demonstrates the module’s best practical performance.