FM RDS Tuner Module for mobile applications using PIC18F46k20

  • Stereo FM band receiver with RDS decoding for mobile applications.
  • Continuous full RDS data output through RS232: RDS PS, PI, TA/TP/TMC, CT, TMC.
  • Full Radio Text supported: 2×64 characters.
  • Raw TMC data output.
  • Low power operation with two AA (HR6) 1V2 Ni-Mh batteries or power supply.
  • Power input range is +2.4V … +3.0V, 50..60mA without OLED and 80..90mA with OLED.
  • Runs on a PIC18F46K20 at 16 MhZ.
  • Full user control (volume, tune, save preset) with a 5-way micro joystick.
  • Module works as stand-alone without OLED as well.
  • Optional OLED Module 1 with RGB OLED 96×64 pixels shows PS (station name), frequency, TA/TP/TMC, PI, mono/stereo, RT (2 alternating lines of radio text)
  • Serial interface control so the module may be used as a stand-alone module.
  • Analog line stereo output.
  • Antenna connection, suggest use of a 30cm -> 2m wire.

 

Circuit explanation / Getting started:

Tuner Module for mobile

PIC18F46k20 The 18F46k20 offers high speed and low power operation. Well suited for a portable application such as this one.
Si4731/4735Small tuner chip, includes a RDS demodulator.
OLED OLED Module 1 with 96×64 pixels RGB OLED, Size: 0.95″Needs a +14V Vdd, this is generated by a TPS61080.
ControlsWith the micro joystick, there are several user controls available. Two for volume (up & down) , tune (left & right) and save preset (short enter.) Zone can be selected on boot:Zone 1 (USA): FM 87,50 -> 108.0 MhZ (75µS setting) To select this zone: left joystick and release on bootup or restart.

Zone 2 (EURO): FM 87,50 -> 108.0 MhZ (50µS setting): Up joystick.

Zone 3 (JAPAN):  FM 76,0 -> 108.0 MhZ (50µS setting): Right joystick.

Serial interface:  tune up and down (tup & tdn) , set frequency (setxxx.x), save preset (sav), get frequency (get), show basic rds info (rds ), reset module (res)

Preset and zone are stored and reloaded on reboot.

PowerThe MCP1640 DC-DC step-up converter makes it possible to power the whole circuit from only one AA battery. We have chosen two AA batteries for enhanced stability and endurance. Power input range is +2.4V … +3.0V Do not exceed this!
PCB: We used as much SMD-parts as possible. The PCB from our shop is a double sided and 100% connection tested PCB with plated-through-hole connections. All holes are drilled already. PCB size = 66,50 x 54.90 mm


Schematics: (eagle-files and library can be downloaded below.)

Full resolution image: schematic and pcb (GIF format) Right-click and save as, then open in an image viewer (sch is too large for some browsers.)

Bill of Materials (Parts List)

Important note: The following sections from the schematic are not needed in this particular setup, and are left out on assembly: EE_PROG, USB+SD, MP3, ACCELERATOR.

For more detail: FM RDS Tuner Module for mobile applications using PIC18F46k20


About The Author

Ibrar Ayyub

I am an experienced technical writer holding a Master's degree in computer science from BZU Multan, Pakistan University. With a background spanning various industries, particularly in home automation and engineering, I have honed my skills in crafting clear and concise content. Proficient in leveraging infographics and diagrams, I strive to simplify complex concepts for readers. My strength lies in thorough research and presenting information in a structured and logical format.

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