Bluetooth 5 for Remote Controlled Toys

By Kristoffer Rist Skøien May 1, 2019

radio-controlled-helicopter

The range advantages of Bluetooth 5 open up opportunities to use the communications protocol for a whole new application: remote-controlled toys and even drones.

Radio-controlled toys have delighted kids and adult hobbyists for generations. The latest iteration of Bluetooth should ensure that the toys can keep pace with modern trends.

Read more: Bluetooth 5 in Smartphones

Technology from toy to hobby

Initially, the first Radio-Controlled (RC) toys used the 27MHz ‘Citizen’s Band’, which is split into a number of different channels varying from country to country. In the US, the band was split into 6 color-coded channels for RC toy use:

  • 1: 26.995 MHz (Brown)
  • 2: 27.045 MHz (Red)
  • 3: 27.095 MHz (Orange)
  • 4: 27.145 MHz (Yellow)
  • 5: 27.195 MHz (Green)
  • 6: 27.255 MHz (Blue)

Matching crystals were used in the toy and the controller, so that the frequency for communication was fixed. In early toys these weren’t changeable so if your neighbour bought the same toy then you could suffer with interference and crosstalk.

As the world of RC toys developed up to hobbyists, interchangeable crystals were introduced to solve this problem. This made it possible for multiple operators to use the same technology in the same space by swapping crystals. It became common for people to fly a coloured ribbon at the top of their controller to indicate their frequency. Regulations in most countries limited the transmitter power, and therefore range was usually around 150-200m in most legal devices!

This was the situation from the mid 1960s - when the toys first appeared - until the early 21st century when companies started developing systems based on the 2.4GHz band used by, for example, portable phones and Wi-Fi. With Frequency Hopping Spread Spectrum (FHSS), toys could for the first time coexist without changing crystals and having to wave your frequency around on a ribbon.

Another advantage of using the 2.4GHz band is that it allows greater bandwidth. The band uses 20MHz channel width so it’s possible to develop systems that can, say, transmit HD video in real time. The obvious cost of such applications is that it would use a ton of battery. So if you have a drone shooting video and sending it to a smartphone, you can probably only use it for around 20 minutes on a single charge.

Despite solving the tricky problem of fixed frequencies, 2.4Ghz also has disadvantages. Toys operating in this spectrum are much more susceptible to line-of-sight problems so if you manoeuvre a toy to the other side of a tree, especially at the end of range, communications would likely come to an abrupt stop. That’s not so problematic for a toy car which will simply stop, but it could result in drones not responding to your commands and continuing in the same direction. Some drones will automatically return home, while others will attempt to return to the last-known radio contact point.

Another issue is the proliferation of proprietary systems that don’t work together. So, if you want a small receiver from Company A that fits better in your car but want a controller from Company B because it handles better, then you’re likely to be out of luck.

Advantages of Bluetooth 5

Previously, Bluetooth communications could theoretically reach up to 200m outside in the clear, although in practice this was closer to 100m. Bluetooth 5 extends that range to 800m, or even more.

Read more: Tested by Nordic: Bluetooth Long Range

If the extra range isn’t needed, Bluetooth 5 can instead take advantage of much increased bandwidth. allowing more data to be exchanged. This could enable real-time camera data to be fed back.

Another advantage Bluetooth has is that it can easily be used for more purposes than simply sending a signal to say ‘left’, ‘right’ etc. Options to monitor conditions such as temperature, humidity and wind speed could be added.

Bringing Bluetooth to toys

Standardization is the first obvious advantage of bringing Bluetooth into the RC toy arena. Any Bluetooth car, boat or drone can be controlled by any Bluetooth smartphone or controller as long as they’re developed to be standards compliant.

The increased range is also a great advantage. Even though most hobbyists won’t want to be more than 1-200m away from their toys, being able to do so reliably and not have to worry about losing a connection could allow long and more interesting race courses for toy cars, for example.

Bluetooth can also make it easier for vehicles to give users valuable feedback about their condition in real time. Traction and engine speed could, for example, alert controllers to adverse conditions so corrective action could be taken. Further, environmental monitoring in drones could allow for safer and more predictable flights.

Finally, Bluetooth brings the possibility of collision detection and avoidance to drones. Using the enhanced broadcasting capabilities of Bluetooth 5, a drone could broadcast its location much like a Bluetooth beacon. Other drones in the area could pick up that information and avoid any collisions.

There are a few toys on the market that use Bluetooth low energy, most notably the Sphero range of smartphone-controlled spherical toys. Toys utilising Bluetooth 5 seem few and far between right now, but that is surely set to change over the next few months as manufacturers realize the flexibility that long range Bluetooth connectivity can bring to their products.

 

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By: Kristoffer Rist Skøien

Kristoffer is a Senior R&D Engineer at Nordic Semiconductor. His main responsibility is embedded firmware development in the Applications department. He holds a M.Sc. and Ph.D. in cybernetics from the Norwegian University of Science and Technology (NTNU)

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