R F - t o - U S B - R D
6
Rev. 0.1
6. RF to USB UART Demo
The RF to USB UART Demo shows how a Sensor Node can be used as a wireless link to transmit data between
two systems. The Sensor Node has four test points for the UART interface, as shown in Figure 6. In order to
perform this demo, an external UART device must be connected to the UART interface. The UART interface
operates at 19,200 baud, 8 data bits, no parity, one stop bit (8-N-1), and no handshaking. The logic level of the
UART is 2.1 V, which is available on the V
DD
pin. Use the V
DD
pin to set the voltage level for the external UART
device.
If an external UART interface is not available, the device can be configured for loopback mode by connecting the
TX and RX pins together. In this configuration, any data sent from the PC application will be transmitted to the
Sensor Node and transmitted back to the PC application.
The CP2103EK UART-to-USB bridge Evaluation Kit, available separately, may be used in conjunction with the
Sensor Node to provide UART-to-USB virtual COM port connectivity. The CP2103EK is recommended because it
provides a separate V
IO
connection, which should be connected to the V
DD
pin of the Sensor Node UART
connector.
Figure 6. Sensor Node UART Interface
The following steps describe how to perform the UART demo:
1. Connect the external UART device to the RX, TX, and GND pins of the UART interface, or connect the TX and
RX pins together for loopback mode.
2. Remove the battery from Sensor Node. Press and hold the button on the Sensor Node, and reinsert the battery.
Release the button on the Sensor Node. The LEDs will blink quickly for 10 seconds or until the button is
released. This step configures the Sensor Node to run the UART demo instead of the Network demo.
3. Launch the UART demo, which is found by clicking
Start
All Programs
Silicon Laboratories
RF to USB
RD
UART
Demo.
4. The USB Dongle serial number appears in the drop-down menu. Click
Connect
to start communication with the
USB Dongle. The application might prompt to update the USB Dongle firmware. Click
Yes
to continue.
UART
GND TX RX VDD
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