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Dynamic_RDS - FM Transmitter Plugin for Falcon Player

Note

Dynamic_RDS supports the QN8066 and Si4713 FM transmitter chips

Originally created for Falcon Player 6.0 (FPP) and updated to support FPP 10.0+, the Dynamic_RDS plugin can generate RDS (radio data system) messages similar to what is seen from typical FM stations. The RDS messages are fully customizable with static text, breaks, and grouping along with the supported file tag data fields of title, artist, album, genre, track number, and track length, as well as main playlist position and item count. Currently, the plugin runs on Raspberry Pi or BBB and supports the QN8066 chip and the Si4713 chip. The chips are controlled via the I2C bus.

Si4713 transmitter board

Originally, the Si4713 breakout board was available from AdaFruit but it now out of stock. There are many clones of this board that can be found on AliExpress or by a Google Search

Note

To reduce system load, the on-board buffers of the Si4713 are used by this plugin. The trade off is not being able to directly control the timing of each RDS message and a limitation of total message length based on how many buffers are available.

Si4713 Breakout Board

QN8066 transmitter board

Important

There are other similar looking boards, so double check for the QN8066 chip. For a detailed look at identifying QN8066 boards, check out Spectraman's video.

Aliexpress link to search for QN8066 FM Transmitter

Radio Board with Screen Radio Board Radio Board Pinout

Antenna

The QN8066 transmitter board requires an antenna for safe operations. Below are some examples of antennas.

Cables, Connectors, and Shielding

Caution

Do not run the PWM wire along side the I2C wires. During testing this caused failures in the I2C commands as soon as PWM was enabled.

Connector info

  • The connection on the transmitter board is a 5-pin JST-XH type connector, 2.54mm.
  • The Raspberry Pis use a female Dupont connector and we recommended using a 2 x 6 block connector.
  • The BeagleBone Black (BBB) use a male Dupont connector.

If you are comfortable with crimping and making connectors, here are examples of what to use

Pre-crimped wires are also an options

Cable for a Raspberry Pi

Raspberry Pi Connection Raspberry Pi to Radio Custom RPi to QN8066 Cable

The green PWM wire runs next to yellow 3.3V and orange GND wire until right before the end to eliminate issue with interference. Keeping the cable as short as possible helps to reduce interference.

Cable for a BeagleBone Black (BBB)

(Cable details for the BBB are still in progress)

Shielding and RF interference

Given the nature of an FM transmitter, interference is potential problem. This interference commonly shows up as I2C errors which become more frequent as transmitter power increases. Moving the antenna away from the RPi/BBB and the transmitter board can reduce this. A significantly more robust setup it to locate the RPi/BBB and transmitter board inside a grounded, metal case such as was done by @chrkov here: Grounded case setup Grounded case setup

Using Hardware PWM on Raspberry Pi

The recommended QN8066 transmitter board can take a PWM signal to increase its power output. Be sure to comply with all applicable laws related to FM broadcasts.

Caution

Do not run the PWM wire along side the I2C wires. During testing this caused failures in the I2C commands as soon as PWM was enabled.

On the Raspberry Pi, in order to use the hardware PWM, the built-in analog audio must be disabled and an external USB sound card or DAC is required. The built-in audio uses both hardware PWM channels to generate the audio, so PWM cannot be used for other purposes when enabled. Software PWM is also an option, but at an increased CPU cost and a decrease in duty cycle accuracy.

From the Dynamic_RDS configuration page, under the Power Settings, enable PWM.

This will automatically modify the /boot/firmware/config.txt:

  1. Comment out all dtparm=audio=on lines with a #
  2. Add the line dtoverlay=pwm,pin=18,func=2 by default Under the Advanced Options at the bottom of the configuration page, the output pin can be selected. This is also where Software PWM can be selected on most other pins.

Tip

Don't forget to change the Audio Output Device in the FPP Settings to use the USB sound card or DAC

Integration with FPP After Hours Music Plugin

The Dynamic_RDS plugin has the ability to work in conjunction with the FPP After Hours Music Plugin to provide RDS Data from an internet stream of music. The information from the stream is populated in the Title field.

Once the After Hours Music Plugin is installed, the integration can be enabled on the Dynamic_RDS configuration pages in the MPC / After Hours Music section.

MPC-After-Hours

Scripting Plugin Changes

During the plugin install, an example script is copied to the FPP media/scripts directory showing how to change the RDS style text. As an example, this could be used to change the PS and/or RT style text to be different during the show verses after. The script is located in scripts/src_Dynamic_RDS_config.sh and the changes are made without having to restart FPP. The single quotes around the style text in the script are important so the Linux shell (bash) won't try to interpret what is in there. Use the script in the media/scripts folder and then use it with the scheduler (via Command -> Run Script) or playlists.

Troubleshooting

Transmitter not working (for the recommended QN8066 board)

  • Verify transmitter is working on it's own

    • Connect the original screen, connect antenna, and 12v power
    • Connected to audio input near the screen connector
    • Check for transmission with a radio. If not, transmitter maybe bad and need to be replaced
    • Remove power, then disconnect screen

  • Verify transmitter is working with RPi/BBB

    • With everything powered off, connect the transmitter to the RPi/BBB for 3v3, GND, SDA, and SCL
    • Do NOT connect the PWM pin
    • Verify each wire is connected correctly 3v3, GND, SDA, and SCL
    • Power up the RPi/BBB
    • Transmitter will power up from power supplied by RPi/BBB (Do NOT connect 12v power yet)
    • Verify the transmitter shows up on the I2C bus at 0x21
      • Either from the Dynamic_RDS config page OR
      • SSH into the RPi i2cdetect -y 1 and run or on BBB run i2cdetect -r -y 2
    • If transmitter does not show up
      • Double check each wire is connectioned correctly 3v3, GND, SDA, and SCL
      • No really, go double check! It can happen to anyone! :)
      • Check each wire's continuity to make sure there isn't a break

Transmitter's RDS not working well

  • Enable Debug logging for the Engine
  • Check for read and/or write errors in plugin-Dynamic_RDS.log
    • If too many errors happen, then I2C fails and the Engine exits
      • Reduce the Amp Power
      • Try using Software I2C
      • Enclose the RPi/BBB and transmitter in a grounded, metal box with the antenna outside of the box
      • Check connection and wire continuity between RPi/BBB
      • Disconnect transmitter 12v power if connected and check I2C bus with i2cdetect -y 1
    • If errors happen at random
      • Make sure the PWM wire does NOT run along side the I2C wires, interference can occur
      • Try to lower the Chip Power and Amp Power, RF interference can impact I2C
      • Move the antenna further away from the transmitter board and RPi/BBB

Plugin Settings

All settings are on the plugin's config page, reachable from Status/Control -> Dynamic RDS. The page auto-detects your transmitter over I2C and hides the settings that don't apply to it.

Note

Settings marked with a lightning bolt icon take effect immediately on the transmitter — no FPP restart needed.

RDS Settings

Setting Default Notes
Enable RDS On Turns off all RDS transmission when unchecked
PI Code 819b Program Identification code. Some older receivers translate this to a callsign — 819b is WRAP, 5F64 is WEBS
Program Type 2 - Information / Current Affairs Standard PTY list; assignments differ between North America and Europe
PS Style Text {T}|{A}[|{P} of {C}]|Merry|Christ-| -mas! Program Service, sent 8 characters at a time. This is what most radios display
PS Update Rate 4 sec Interval between 8-character updates (3-60). It takes ~1 second to send 8 characters, and some radios only display text after receiving a group twice
RT Style Text {T}[ by {A}][|Track {P} of {C}] Merry Christmas! Radio Text — longer messages, slower update rate
RT Update Size 32 chars RT supports up to 64, but not all radios display that much at once. 32 is recommended
RT Update Rate 7 sec Interval between RT updates (3-60). Sending a full 64 characters takes ~4 seconds

Style Text Substitutions

The PS and RT style text fields accept substitutions that are filled in from the currently playing media:

Code Value
{T} Title
{A} Artist
{B} Album
{G} Genre
{N} Track Number
{L} Track Length, as 0:00
{C} Item count in the Main Playlist section
{P} Item position in the Main Playlist section

Formatting rules:

  • Any static text can be mixed in freely
  • | (pipe) splits between RDS groups, acting like a line break
  • [ ] creates a subgroup — if any substitution inside is empty, the whole subgroup is dropped. This is how you avoid stray text like "by" with no artist
  • Use \ in front of | { } [ ] to display those characters literally
  • The end of the style text implicitly acts as a line break
  • {P} is set empty when both it and {C} are 1, to prevent "Track 1 of 1" messages

Transmitter Type and Settings

Setting Default Notes
Transmitter Type Auto-selected Set from I2C detection (QN8066 at 0x21, Si4713 at 0x63). Can be overridden manually
Frequency 100.10 60.00-108.00 for QN8066, 76.00-108.00 for Si4713
Preemphasis 75 μs 75 μs for the US and South Korea, 50 μs for most of the rest of the world
Antenna Tuning Capacitor (Si4713) 0 0 lets the chip auto-tune; manual range is 1-191
Reset Pin / GPIO (Si4713) Pin 7 / GPIO 4 The Si4713 needs its reset pin high for normal operation

Audio Settings (QN8066)

Setting Default Notes
Gain Adjustment 0 Range -15 to +20. Too high or too low causes distortion, random dropouts, or silence
Enable Soft Clipping On
Enable AGC Off Not recommended

Power Settings

Setting Default Notes
Chip Power (QN8066) 122 Range 92-122
Chip Power (Si4713) 115 Range 88-120. Voltage accuracy above 115 dBμV is not guaranteed
Enable PWM (QN8066) Off Hardware PWM on Pin 12 / GPIO 18 by default, used to control amplifier power. Requires on-board audio to be disabled, so an external sound card is needed
Amp Power (QN8066) 0 Range 0-100, controlled via PWM output

Plugin Activation

Setting Default Notes
Start with FPPD Start Or Playlist Start, or Never. On start the transmitter is reset, settings initialized, audio broadcast begins, and static RDS messages are sent
Stop with Never Or Playlist Stop. On stop the transmitter is reset and listeners hear static

MPC / After Hours Music

Enable to pull %title% from mpc and display it as {T} when FPP is otherwise idle. Only appears if the After Hours Music Player plugin is installed.

MQTT

Publishes plugin status to MQTT. Requires MQTT to be configured first under FPP Settings -> MQTT, and python3-paho-mqtt, which can be installed with a button on the config page.

Log Levels and Logs

Callback and Engine logging levels are set separately (Errors Only / Warn / Info / Debug, plus Excessive for the Engine). Both write to plugin-Dynamic_RDS.log, viewable from the config page.

Report an Issue

Set the log levels to Debug, reproduce the problem, then use Download log and config zip and attach the file to a new issue. The zip contains the log and rotated copies, the plugin.Dynamic_RDS config, last RDS output, the plugin version, and your Pi/BBB boot config.

Advanced Options

Software I2C mode for the Raspberry Pi, and PWM pin selection for both the Pi and BeagleBone Black. Most setups won't need to touch these.

About

Falcon Player (FPP) plugin for managing QN8066 or Si4713 FM transmitters to broadcast custom RDS messages like a real station. Reads media metadata and playlist fields, supports MQTT, and integrates with the After Hours Music plugin (MPC). Runs on Raspberry Pi or BBB.

Topics

bbbfalcon-pluginfmqn8066radioraspberry-pirdssi4713transmitter

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