User guide

Si471x-EVB
Preliminary Rev. 0.4 11
IMPORTANT: Jumper Settings
Because of the many possibilities available to configure the EVB, please make sure that these four jumpers are set
accordingly:
1. J41: GPO3/DCLK setting
2. J44: TX/RX setting for Audio1 I/O
3. J45: TX/RX setting for Audio2 I/O
4. J5– J13: Analog Audio Source, RCA or Line In
J41: GPO3/DCLK Setting
Upper - DCLK digital audio clock
Lower - GPO3 digital control signal
For configuring the Si471x digital audio input, make
sure that the jumper is set in the Upper position so that the DCLK signal will be routed to the Si471x.
J44: TX/RX setting for Audio1 I/O
Upper - Audio1 is set to FM transmit (pin 13&14 will be the digital audio input).
Lower - Audio1 is set for FM receive (pin 13&14 will be analog/digital audio output).
J45: TX/RX setting for Audio2 I/O
Upper - Audio2 is set to FM transmit (pin 15&16 will be the analog/digital audio input).
Lower - Audio2 is set for FM receive (pin 15&16 will be the digital audio output).
Please refer to the jumper setting instructions found in the Si471x GUI software when configuring the board.
J5–J13: Analog Audio Source, RCA or Line In
Upper - RCA inputs are used for analog audio source.
Lower - Line inputs are used for analog audio source
3.3. Si471x Daughter Card
3.3.1. Si471x FM Transmitter Chip
The Si471x (U1) and its bypass capacitors and tuning inductor (L2) are located on the daughter card. The FM
Transmit output can be configured in three different ways:
1. Built-in antenna
2. External antenna
3. RF output
Built-in Antenna
To use the 6 cm trace built-in antenna, please make sure to put a 0ohm resistor in R2 and remove R3 resistor.
External Antenna
To use an external antenna, please remove both R2 and R3 resistors. Put the external antenna in the J2 header
connector.
Rf Output
To analyze the performance of the Si471x FM Transmitter Output, please put a 0ohm resistor in R3 and remove R2
resistor. The FM RF output will be available through the SMA connector J1.
Refer to “AN306: Antenna Interface" for a more complete study of the antenna interface for the Si471x.