VMR6512 Hi-Fi Audio FM Transmitter Module

General Description
VMR6512 is a highly integrated FM audio signal transmitter module. It integrates advanced digital signal processor (DSP), frequency synthesizer、RF power amplifier and matching network. So it can realize FM audio modulation without any external components. VMR6512 can also achieve broadcast quality sound by using digital pre-emphasis, digital filtering, automatic gain control and digital frequency control technologies.

Features
 ●Broadcast  standard sound  quality
 ●Fully integrated encapsulation, it can work without any external components.
 ●Audio frequency processed by DSP, guaranting high quality sound 
 ●Using frequency synthetic technology, high stability of oscillation frequency
 ●Output power adjustable. (up to 115dBuV)
 ●Frequency range is 88.0MHz to 108.0MHz, low-end can be extended to 76.0MHz upon request.         
 ●It can input analog audio or digital audio
 ●It possesses external UART interface and can be easily controlled by external  CPU or PC machines
 ●It provides frequency setting UP / DOWN input and can be used independently.

Applications
 ●Hi-Fi wireless headphone
 ●MP3 audio transponder in the car
 ●Wireless microphones
 ●Conference Broadcasting System
 ● In building music broadcasting
 ● In park music broadcasting
 ●Accessories of audio-visual entertainment equipment
 ●Radio station in campus

Testing Circuit

Pin Description

Electrical parameters

Block Diagram

Functions

●Reset

Set Reset pin to high will reset  the module including the controller, DSP and frequency synthesizer. After reset, the transmission frequency will be100.0MHz, transmission power will be 115dBuV. The system begins working 160ms after the Reset signal becomes lower.
●Analog audio input Rin, Lin
Rin and Lin  are  the analog audio signal input pins of  the module. There is a capacitor  connected to the pin inside the module. So the other external components are not needed. Audio input impedance is approximately 56kΩ, the maximum input signal level is 350mVp-p.

●Digital audio input interface
Digital audio input interface is consisted of SCLK, DIN and FS signals. It can be set to I2S, DSP and Left Justified three different formats through commanding and connected gluelessly with almost all the DSP and Coded.
●UP / DOWN pin
UP and DOWN pins are used to change the operating frequency  when working without the external controller. Each low impulse greater than 0.05 seconds  applied on UP / DOWN pin will make output RF  frequency increase or decrease 0.1MHz. If you stay low level, then the operating frequency will change continuously every 0.3 seconds.
●RF output
As the module has internal matching networks, RF output signal pin RFout should be directly connected to the antenna without any components. It is proposed that antenna should use 1/4 wavelength wire or rod antenna. Certaintly you can use other high-efficiency antennas. The matching impedance of the antenna should be 50Ω.
●Digital / analog input selection D / A #
This signal is used to select the audio input modeof the module. Digital input is used when it is high level, otherwise, analog input will be used.

●Control interface RXD / TXD
Control interface is consisted of RXD and TXD signals. The used communication protocol is asynchronous serial UART, baud rate is 19200 and the format is 8bits. One start bit, one stop bit, no parity(19200,8,1,0).

External controller controls the the module by sending command through UART. The command is 1 byte and the parameter is 2 bytes. Therefore, the length of each command string is 3 bytes, as shown below:

After receiving the command, if the module implemented successfully, it will return to 0x80, followed by 2 parameter bytes. If it fails, it will return a byte 0x00.

Command list is as follows:

Package