feature of product:
  1: Use advanced digital audio signal processing technology (DSP) and FM phase-locked loop modulation technology (PLL) to make the sound quality more realistic, performance more stable, and long-term working frequency without deviation.
  2: LCD display is more intuitive and accurate, with extremely low power consumption and minimal noise interference.
  3: It has the functions of automatic search and storage of radio stations, easy to operate and use.
  4: Built-in 30-level digital volume adjustment, key operation can be easily completed.
  5: Automatically memorize the data before the power failure.
  6: Support serial AT command control.
  7: Using quartz crystal for frequency stabilization, the emission frequency will no longer drift when the temperature changes.
  8: The full frequency band automatically searches for signal frequency bands and stores them in memory.
Product parameters:
  Output power: 500mW (drive earphone)
  Frequency response range: 50Hz-18KHz
  Channel: stereo
  Receiving frequency adjustment range:
     Turn off campus radio 87.0MHz-108.0MHz, turn on campus radio 76.0MHz-108.0MHz
  Equivalent noise: ≥30dB
  Supply voltage: 3.0V-5.0V
  Current: 40mA
Instructions for use:
1: Line connection
  All function outputs of this module are reserved for external ports, and users need to connect to the corresponding circuit module to work normally.
<1>: Connect the audio cable
  The corresponding ports AGND, Output R, and Output L of the module are respectively connected to the ground, left channel and right channel of the audio output line.
<2>: Connect the power cord
  The corresponding port GND and VCC of the module are respectively connected to the negative and positive terminals of the power supply (battery). It is recommended to use a battery or other regulated power supply for the power supply. Do not use switching power supplies without filters (such as mobile phone chargers, and other low-quality switching power supplies), otherwise the interference generated by the power supply will affect the normal operation of this module. The normal working voltage of this module is 3.0-5.0V, and the power supply voltage should not exceed this range.
<3>: Connect the button
  All the buttons of this module are led out by reserved ports, and customers can access the corresponding function buttons according to their needs. The buttons can be used with ordinary touch buttons, one end is connected to the corresponding button port of this module, and the other end is connected to the module GND or AGND terminal. Some buttons have long press function (such as volume +/- long press for continuous +/- volume), long press for more than 2 seconds is effective.
<4>: Connect the antenna
  The ANT port is used to connect the FM antenna. In order to better receive (transmit) FM signals, it is recommended to connect an external whip antenna with a length of 75cm, and there should be no obstacles as far as possible near the antenna.
<5>: Connect to the serial port (no need to connect to serial port control)  The module reserves a TTL level serial port control interface. The communication between the TTL serial port and the module needs to be connected to the module's UART_RX, UART_TX and GND, and the external MCU (microcontroller) or computer serial port can be used to send commands to control the relevant functions of the module. Note: Because the computer serial port level is not TTL level, you need to connect the RS323 level to TTL level replacement device when connecting to the computer or use a USB to TTL level serial port module to communicate with this module. Because the serial port command control module requires a certain degree of computer expertise, buyers who do not understand do not need to toss. For all information, please refer to the description of the baby, and the customer service does not provide technical guidance in this regard.
2: Automatic channel search:
  This module comes with FM radio storage function. Long press "Auto Search" to start automatic search and store the radio stations that can be listened to. After the search is completed, the first radio station P01 will be played automatically. The user can press the "previous station" or "next station" button to switch the searched station.
3: Mono/Stereo:
  This module can flexibly set the mono demodulation and stereo demodulation modes. The MONO two solder joints on the back of the PCB board are connected together for mono demodulation mode, and disconnected for stereo demodulation mode.
user settings:
   This module can set the backlight state and whether to listen to the campus broadcast frequency band according to the user's specific usage. The setting method is as follows. When the power is off, press and hold the VOL+, VOL- button and power on the LCD display C1 to turn on the campus broadcast C0 to turn off the campus broadcast band, and the settings will take effect after restarting. To set the backlight state, press and hold the up and down radio buttons at the same time when the power is off. B1 indicates that the backlight is always on, and B0 indicates that the backlight is turned off for 20 seconds. The settings will take effect after restarting. Change the setting status and repeat this step to switch. The factory is uniformly set to not turn on the campus broadcast frequency band, and the backlight goes out for 20 seconds without operation.
Precautions:
  1: The power supply voltage must not exceed the supply voltage range of this module.
  2: Do not touch the back components of the module when working, so as not to affect the normal operation of the module or cause a short circuit to burn the module.