Hardware description and configuration

Powering the evaluation board

There are several options to supply power to the evaluation board's module.

USB

Verify the J4 jumper is installed. Then use a mini-USB cable to connect the USB-UART connector to a USB power supply or PC.

USB

Unregulated external supply

Apply 5 VDC across the gold pads at the bottom edge of the evaluation board. The positive terminal is the left-hand terminal.

Unregulated external supply

Regulated external supply

Remove resistor R1. Then apply 3.3 VDC across the ALT VCC pads.

Regulated external supply

Arduino or Raspberry Pi

The module will derive power from a connected Arduino or Raspberry Pi.

Antenna selection

The module on the evaluation board can be configured to transmit/recieve radio-frequency signals via its integrated trace antenna or via an external antenna connected to the board's SMA connector.  Use of an external antenna can lead to improved performance relative to the trace antenna. To switch the configuration of the module using the command line utilities provided by Link Labs, please refer to this article.

For operation in the US ISM band (902--928 MHz), Link Labs recommends the Linx Tech ANT-916-CW-HWR-SMA, which is a center-fed half-wave dipole antenna.

LED indicator

The evaluation board includes a single red light-emitting diode (LED), labeled IO0. The LED illuminates anytime the module sets the host interrupt line (i.e., when one/many of the module's interrupt flags is/are latched).

LED indicator

RESET pushbutton

The evaluation board includes a RESET pushbutton. Depressing this button drives pin 7 low (the module's pin 7). When the button is released, an internal pull-up drives pin 7 high to actuate a hardware reset.

USB-UART jumper

The USB-UART jumper (or J4 jumper) provides a method to disconnect the Silicon Labs CP2104 USB-UART bridge from the module. Disconnecting the bridge may be useful when the USB-UART connection is not needed.

USB-UART jumper

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