An Inexpensive FM Receiver For The Raspberry Pi

A Raspberry Pi next to a small circuit board

At this point, there are no shortage of impressive hacks for the Raspberry Pi. [Dilshan Jayakody] recently documented his experience in designing and building an inexpensive FM Stereo Receiver for the Pi platform, and the results are impressive.

Quite a few FM receiver projects center around the RDA5807 or TEA5767 ICs, however [Dilshan] has used the QN8035 by Quintic Corporation in his build. A handful of discrete components on a pleasing single-sided PCB is all that is needed to interface the QN8035 with the Pi’s I2C bus.

After demonstrating that the FM tuner could be, well, tuned at the command line, [Dilshan] then coded a smart looking GUI application that makes tuning a breeze. The software allows the listener to manually and automatically scan through FM stations, decode program service data, control the volume, and display the RSSI and SNR readings from the tuner.

As we reported earlier, FM radio is on a slow decline into obsolescence. This latest project isn’t aiming to break new ground, however its simplicity and inexpensive components are the perfect combination for beginner hackers and radio enthusiasts alike. More details can be found over on Hackaday.io. The schematic, source code and bill of materials can be found on GitHub.

 

36 thoughts on “An Inexpensive FM Receiver For The Raspberry Pi

  1. “FM radio is on a slow decline into obsolescence”

    Not in cyclone-prone regions. It’s often the only way information can be disseminated after a big one. A cheap wind-up receiver is part of our storm prep kit. And cyclones ain’t getting smaller…

    1. This is all true. During the recent Australian bushfires, it was my little battery powererd AM/FM/Airband radio that kept the entire extended family up to date when the power was out for 72+ hours.

      However, I would still argue that FM is now obsolete. If given the choice, I’ll always reach for my phone or laptop to listen to music and talk. Doesn’t mean I won’t be packing my battery powered radio on my next trip!

      1. Wow I haven’t seen this much knee jerk negativity since that guy did that thing And made a bunch of money. I’ve been supporting, giving $;to a small low power FM radio network for 15 years. This kind of device is not a world changer, instead maybe it’s the launchpad for the next world changing device!

    2. “And cyclones ain’t getting smaller…” Well actually if you look at the AU BOM site there is a graph on the page “Tropical cyclone climatology” that indicates that the frequency of severe cyclones is in decline since the mid 1980’s. However that does not mean that they are not about to ramp back up again as part of an 80 year cycle (because it is impossible to predict the future of a chaotic system). It is hard to find patterns in climate when the minimum sample size to detect a pattern in long cycles is around 500 years.

  2. Anybody know of cheap dap+ chips that do the same? What about chips that only tune? E.g. let the decoding be done in software? Could one feed the (analoge) output of one of the chips in this article be fed into a pi’s ADC? SDR dingles obviously can do this of course …

    1. Here in Germany, FM is still no.1, too.
      It will go away after 2025, maybe, but not yet.

      I guess people are simply happy with FM on the Ultakurzwelle/UKW (Ultra Short Wave) band.

      The only drawback is, though, that if DAB+ fails, traditional radio will be replaced altogether by web radio, which is utter nonsense.

      In a catastrophe, people need a way to receive broadcast, to hear the news, messages from the authorities – and internet / the mobile phone towers are the first ones to fail. They cannot handle 80 million or more requests simultaneously in a catastrophe. πŸ™„

  3. That’s great news. I’ve been wanting to put a radio in my bathroom for a long time. Tired of listening to the classics on loop. I think radio stations will live on for a long time to come. Of course it’s not such a popular format among young people, but older people listen to the radio.

    1. Though I’d point out that younger people who aren’t in the habit of listening to the radio turn into older people who aren’t in the habit of listening to the radio, I think you’re basically right. The sheer “it just works” of my car radio means that even though I use radio far less than I used to, I’m never (fully) gonna give it up or desert it.

  4. I’ve been listening to fm radio on my rtlsdr with gqrx, though sadly it crashes a fair bit. it’s a pity that stereo wasn’t rolled into the rtl_fm repo, to make it easier to use on limited processors.
    I like that i don’t have to swap audio cables with the sdr, and it’s cheap too.

        1. I’ve been planning this as well! Even started buying little components, like the above mentioned RDA chip, to test different things. I’d be really interested to see what you come up with for yours! I’ve even been tossing the idea around to buy a ~$250 Chinesium android head unit to see if I can spruce it up into something worth having.
          I really want to be able to incorporate my CB and HAM radios in some way though, in terms of audio passthrough and control that is, so I’m probably going to end up rolling my own. Maybe I’ll add some extra RF receivers for simultaneous multiple band/frequency monitoring heh.

    1. That really depends now doesn’t it. If this is just a start to making a Pi Based audio system then not so much. Add in a good audio system and you could make an stereo system. Add in a CD/DVD player and audio in jacks and out jacks and you could have a pretty interesting device. Or you could make a DIY car stereo head unit.
      But also don’t discount that it is just flat out easy to develop on the pi. You can do it all on the actual hardware and even prototype the software in python. It is just flat out easy. And this isn’t a product it is a project.

  5. I remember looking at a Raspberry PI schematic (don’t remember the model) and it had FM radio on the “CPU”. But it wasn’t used to lower the manufacturing costs.

    In the commentvsection there were a lot of people kind of upset about the fact it wasn’t used.

  6. FM radio is on a slow decline, but not into obsolescence. It’s on a slow decline simply because the ownership of all the frequencies is concentrated in the hands of a few players.

    The large-capital funds who have taken over radio are content to push the programming to, ahem, “AM radio quality” (cheap, divisive talk radio).

    This has huge implications on the culture. Local music acts simply do not get introduced to the public via their local FM stations. Instead they must appeal to the national face of the networks and then selected act is pushed out nationally. This is awful.

    We all know that the electric costs of radio are almost nothing, and we all know it’s a good space for open source and automation. Unfortunately the FCC promise of “local low-powered radio” was a ruse, never came to pass.

  7. The rationale for selecting a QN8035 over the (ubiquitous and unmentioned) Si Labs si47xx series eludes me. Sure there is price, but let’s be realistic here: an extra ~$9 and you have AM, SSB, SW, MW, and LW in addition to the VHF on a IC that requires fewer external components. This inherently yields an identical, if not smaller, board footprint. If cost was an issue, the RPi should have been replaced with any of the Espressif throw-aways. Given the existence of previous HaD posts on the si47xx IC and the inferiority of the QN8035, I can only conclude the goal of this project was to score a HaD article, and a success. I’m not attempting to demoralize or discredit the effort that went into it – I’m merely stating that the project could have yielded superior functionality with comparable effort. To illustrate this rhetorical perspective via metaphors: Would you wire your home with Cat3 because that’s all you need right now, or would you spend the extra money and upgrade to Cat6? Would you change your vehicle’s engine oil without changing the filter, just because the filter will last another 1,000 miles? Would you purchase a laptop with an Intel i5 if an i7 was $50 more? I implore you to refrain from summoning the circumstantial-use monster: I’m perfectly aware that some of you run everything from blenders to lawnmowers on coin cell batteries. I’m aware clipboard warriors beat people to death with budgets, desktop virtualization exists, core speed/cache size, blah blah special purpose rainbow unicorn fart blah blah. Hyperboles aside, the point is simple – Time is an investment, utilize it efficiently and future proof your design. The RPi use may seem overkill, however it does allow for expansion.To me it’s comforting to know that I can just grab the closest radio when SHTF and have immediate access to police, fire, maritime, weather, and other emergency broadcasts. When this luxury is coupled with additional creature comforts such as the ability to listen to your drunken neighbor poorly re-eanact an episode of Netflix’s Frequency, the ability to hear local AM sports broadcasts, and the ability to share any of the aforementioned with other devices (via Wifi, P2P, BLE, or Bluetooth), your desire for its prevalence increases.

  8. In the summer of 2019 all the corporate radio oldies radio stations around me stopped playing anything before 1970. It took a week for me to figure out what was going on. It took only seconds to remove those presets from all my tuners, car, home, and work. THE decade 1965-1975 chopped in half. One station calls itself classic 80’s rock. Which are they?

    I wonder how well this radio chip stacks up against a good Pioneer car tuner. I can get the 60mi distant NPR station that our local tried to jam out of town, just adjacent to it. Tables turned, our 40kW NPR station gets “hammered” in half of town by a sports AM translator only 2 channels away located right in town. It takes a top performance tuner just to get anything worth listening to.

  9. “However, I would still argue that FM is now obsolete. If given the choice, I’ll always reach for my phone or laptop to listen to music and talk”

    Chris, the problem with phones, laptops and other internet devices is that you require a working connection to the internet and power to recharge. Telstra’s mobile phone towers have, at best, two days worth of battery back-up. They used to have generators that were kept topped up with diesel by local volunteers but that was canned over a decade ago. I’m not sure about fixed wireless NBN towers as we haven’t had a big one since their introduction. Telstra exchanges allegedly have generators and can last a few days assuming they have a sufficient diesel supply.

    And if anyone suggests home generators and other similar solutions I would add that few people will shell out for a device that they may use for a few days each decade and may not even start due to lack of use/maintenance. btw the only death after Cat 5 Cyclone Yasi was someone that kept a genny running at home and died from carbon monoxide poisoning.

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