Low Power Bluetooth Advertising Chip Without SoC

Asahi Kasei Microdevices Corporation has announced the AK1595. As with the previously mentioned AK1594, it works without a System on a Chip and provides Bluetooth transmission using very low power.

Instead of setting the advertising via EEPROM programming like the AK1594, the AK1595 is controlled via UART or I2C making it suitable for variable data transmission scenarios.

We expect the AK1595 will be particularly useful for energy harvested applications.

A Push for Bluetooth 5 Long Range

There’s a push by the Bluetooth SIG at the moment, promoting long range Bluetooth that appeared with Bluetooth 5 in June 2016. This is presumably because, to date, there haven’t been many long range end-user products. There aren’t many devices out there because you need Bluetooth 5 hardware at both ends of communication and existing devices can’t be upgraded.

Device manufacturers have been waiting for the ‘device at the other end of the communication’ (beacons, sensors, smartphones, single board computers) to become compatible before creating new products using Bluetooth 5 which is a chicken and egg situation. There are also tradeoffs around backwards compatibility and battery power. It’s more complex to create a device that supports Bluetooth 5 and is backwards compatible with Bluetooth 4. Advertising both at the same time uses more power and hence reduces the battery lifetime.

In order to validate Bluetooth 5’s long range claims, Nordic have a new blog post testing long range. The post gives a good explanation of path loss, outside vs inside and deterioration of the signal due to precipitation, humidity and reflected signals. Nordic also have an older post comparing the range of BLE, ZigBee and Thread Protocols.

Read more about Bluetooth 5

Bluetooth 5 Range Tests

Unseen Tech has a recent whitepaper on Bluetooth 5 range. It describes some tests that were performed to assess Bluetooth 5 to see the improvements in range compared to Bluetooth 4’s typical 30m to 100m. The tests used development boards from Texas Instruments and Nordic that, used outside, achieved about 650m and 750m respectively.

While some companies are claiming Bluetooth 5 support in products, many don’t actually use Bluetooth 5 yet but instead offer an upgrade path to Bluetooth 5. Other’s do offer Bluetooth 5 but downgrade to Bluetooth 4 when communicating with Bluetooth 4 devices (e.g. smartphones) which are still the large majority of devices.

There are also some ultra long range Bluetooth 4 devices that include output power amplifers that can achieve ranges of hundreds of metres and we have one USB powered beacon that reaches up to 4Km.

Bluetooth Range Estimator

The Bluetooth SIG, who create the specifications for Bluetooth, have a new Bluetooth Range Estimator that takes into account the environment, transmit power, antenna gain and received gain to provide an estimated range.

There’s also an associated blog post on 3 Common Myths About Bluetooth.

In terms of beacons, the range usually relates to how they are powered. The beacons with smaller CR2032 batteries tend to be designed for ranges up 50m. Larger CR2477 powered beacons usually reach about 100m. AA battery beacons or those with power amplifers reach hundreds of metres. and some USB beacons can reach up to 4Km. These ranges are outdoors. Indoors, there’s often radio reflections and blocking that reduce range. Beacon orientation can also affect range.

Bluetooth 5 Packet Sniffing

When testing beacons and Bluetooth LE, nRF Connect is usually sufficient. However, if you need deeper analysis of Bluetooth you need to use a packet sniffer.

NCC Group has a new open source sniffer for Bluetooth 5 that also works with Bluetooth 4.x. You need to run the software on a Texas Instruments (TI) CC26x2 board.

The source code and instructions are available on GitHub.

New Bluetooth Direction Finding Feature

A new direction finding feature has been released for Bluetooth 5.1 (pdf). Using more than one antenna, as used by Quuppa, allows for direction finding.

The paper on Enhancing Bluetooth Location Services with Direction Finding explains how location services currently use RSSI to estimate the distance. Direction finding introduces more advanced Angle of arrival (AoA) and angle of departure (AoD) techniques into Bluetooth 5.

“Should smartphone vendors choose to include Bluetooth direction finding with AoA support in their products, item finding solutions could be enhanced to provide directional information.”

As with the move from Bluetooth 4 to Bluetooth 5 it’s going to be while before we see (non Quuppa) products with direction finding. This feature requires specific hardware and software. Before that, it needs SDKs from the SoC vendors. Existing smartphones, beacons and gateways won’t be able to be upgraded.

Read about Using Beacons, iBeacons for Real-time Locating Systems (RTLS)

Bluetooth 5 in Smartphones

Last February we wrote about the progress of Bluetooth 5 in recent smartphones. A few months on and Nordic Semiconductor, the company that produces the System on a Chip (SoC) used in most beacons, has a new blog post on Bluetooth 5 in Smartphones and how we are about to experience a tipping point in support for Bluetooth 5.

The final observation from the article is:

Even if sticking to previous incarnations of Bluetooth may look like the right choice, the marketing power of Bluetooth 5, regardless of whether it’s needed or not, is likely to help companies differentiate products and increase sales.

This is true. Some companies currently claiming Bluetooth 5 support in products don’t actually use Bluetooth 5 yet but instead offer an upgrade path to Bluetooth 5.

Bluetooth 5 Simultaneous Multiple PHY

If you have been following our posts on Bluetooth 5, you might be wondering how one Bluetooth device can communicate to many devices, some of which might be legancy Bluetooth 4.

There’s a new video from Nordic Semiconductor (who produce the System on a Chip – SoC – inside most beacons) where the new long range mode is used while connecting to up to 20 devices. These can be different PHYs meaning that different capabilities, for example high speed vs long range vs legacy) can be connected at the same time.

Update on Bluetooth 5 and Beacons

It’s nearly a year since we wrote about Bluetooth 5 Beacon Implementation Tradeoffs.

Since then, the Samsung S8, iPhone 8/X, and Google Pixel 2 have been released that support Bluetooth 5. However, while these support the LE 2M high speed PHY they don’t support the longer range PHYs. There are currently no smartphones that can take advantage of Bluetooth 5’s longer range.

There are few true Bluetooth 5 beacons. Most that say they are Bluetooth 5 ‘ready’ or ‘compatible’ are only compatible to the extent that their firmware can be upgraded in the future.

An exception is SNCF, the French train company, who are manufacturing their own beacons in order to start experimenting with Bluetooth 5. As mentioned in the Mr Beacon video, SNCF are looking to Bluetooth 5 to provide for (up to x4) better beacon battery life. How is this possible, especially as the SoC chips themselves (usually nRF52 or TI CC2640) are the same whether they run Bluetooth 4 or 5? The battery current is actually the same. Bluetooth LE devices consume most power when actually transmitting and negligible power inbetween transmissions. The faster data rate allows the Bluetooth device to transmit the same data over less time thus using less battery power.

Bluetooth 5 Advertising Extensions

There’s an interesting new article on the Nordic Blogs on Bluetooth 5 Advertising Extensions . It explains how the number of channels is increasing, from 3 in Bluetooth 4.0, allowing larger advertising payloads in one of the 37 other data channels. A single advertising packet can hold up to 255 bytes of data, up from 37 in Bluetooth 4.0. The chaining of packets allows for larger payloads up to 1650 bytes.

As the article mentions, we have to wait until tablets and smartphones support Bluetooth 5. Also, we have to wait for new Beacons with Bluetooth 5.