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How to use NFC Tags on Android
Aug 07, 2018

How to use NFC Tags on Android

Just like Bluetooth and WiFi, and all manner of other wireless signals, NFC works on the principle of sending information over radio waves.  Near Field Communication is another standard for wireless data transitions, meaning that there are specifications which devices have to adhere to in order to communicate with each other properly. The technology used in NFC is based on older RFID (Radio-frequency identification) ideas, which uses electromagnetic induction in order to transmit information.

This marks the one major difference between NFC and Bluetooth/WiFi, as it can be used to induce electric currents within passive components as well as just send data. This means that passive devices don’t require their own power supply, and can instead be powered by the electromagnetic field produced by an active NFC component when it comes into range, but we’ll talk about that in greater detail some other time. Unfortunately, NFC technology does not command enough inductance to be used to charge our smartphones, but QI charging is based on the same principle.

Electromagnetic fields

Electromagnetic fields can be used to transmit data or induce electrical currents in a receiving device. Passive NFC devices draw power from the fields produced by active devices, but the range is only short.

The transmission frequency for data across NFC Tags is 13.56 megahertz, and data can be sent at either 106, 212 or 424 kilobits per second, which is quick enough for a range of data transfers – from contact details to swapping pictures and music.

In order to determine what sort of information is to be exchanged between devices, the NFC standard currently has three distinct modes of operation for compliant devices. Perhaps the most common use in smartphones is the peer-to-peer mode, which allows two NFC-enabled devices to exchange various pieces of information between each other. In this mode both devices switch between active, when sending data, and passive states when receiving.

Read/write mode, on the other hand, is a one way data transmission, where the active device, possibly your smartphone, links up with another device in order to read information from it. This is the mode used when you interact with an NFC advert tag.

The final mode of operation is card emulation, whereby the NFC device can be used like a smart or contactless credit card in order to make payments or tap into public transport systems.

Comparisons with Bluetooth

You might think that NFC is bit unnecessary, considering that Bluetooth has been more widely available for many years. However, there are several important technological differences between the two that gives NFC some significant benefits in certain circumstances. The major argument in favor of NFC is that it has much lower power consumption than Bluetooth. This makes NFC perfect for passive devices, such as the advertising tags that we mentioned earlier, as they can operate without the need for a major power source.

However, this power saving does have some major drawbacks. Most noticeably that the range of transmission is much shorter than Bluetooth. While NFC has a range of around 10cm, just a few inches, Bluetooth connections can transmit data up to 10 meters or more from the source. Another drawback is that NFC is quite a bit slower than Bluetooth, transmitting data at a maximum speed of just 424 kbit/s, compared with 2.1 Mbit/s with Bluetooth 2.1 or around 1 Mbit/s with Bluetooth Low Energy.

But NFC does have one advantage when it comes to speed, faster connectivity. Due to the use of inductive coupling, and the absence of manual pairing, it takes less than one tenth of a second to establish a connection between two devices. While modern Bluetooth connects pretty fast, NFC is still super handy for certain scenarios. Namely mobile payments.

Samsung Pay, Android Pay, and even Apple Pay for iOS all utilize NFC technology — though Samsung Pay works a bit differently than the others. While Bluetooth works better for connecting devices together for file transfers, sharing connections to speakers, and more, we anticipate that NFC will always have a place in this world thanks to mobile payments — a technology that is quickly on the rise.