The second coming of Sigfox

Sigfox was set up in 2010 to act as a managed wireless connectivity provider for IoT devices that need to be constantly monitored, but which only exchange very small amounts of information with their back-end services.

Sigfox connections run on the unlicensed ISM band, making them easy to incorporate in products without having to worry about licensing requirements.

The emergence of WND as an alternative Sigfox network provider in the UK to Arqiva, which was first on the scene, is reigniting interest in Sigfox as an enabling technology for IoT roll-outs. The fact that WND is rapidly extending the geographic coverage of the protocol is aiding the cause.

Sigfox has been designed to overcome three key issues holding back IoT rollouts: the availability of a global network; support for ultra-low power end-node devices (think sensors powered by energy harvesting) and; very low silicon implementation costs when compared, for example, to a cellular connection.

Sigfox has just launched more services to further simplify the roll-out of IoT ecosystems. ‘Admiral Ivory’ is a simplified connectivity service which makes it possible to transform short-range wireless devices into a long-range IoT node, using low-cost hardware similar to that found in a garage door remote control.

The company reckons the cost is so low that it could be used in disposable applications, such as parcel, retail and freight asset tracking. The new service slots in below Sigfox’s ultra-low-cost connectivity solution, now known as ‘Admiral Blue’, which enables modules costing as little as $2 to send very small data packets over long distances using very little power.

Sigfox’s ‘Monarch’ service enables IoT devices to adapt the frequency upon which they are operating within the ISM band (from 862-928MHz) to suit local preferences worldwide. It is done using a radio recognition service that does not need additional hardware in the Sigfox device. The service should make it easier for IoT designers to create devices that can work anywhere in the world, simplifying both the hardware design and the management overhead of creating a global IoT ecosystem.

As part of the introduction of these services, Sigfox has rebranded its geolocation service as Atlas. This uses radio-signal analysis to determine a device’s location, without the need for additional hardware beyond that already in the Sigfox chip.

In support of these services, Sigfox has also introduced a partner network, a portal through which users can access the resources they need for an IoT project, ranging from basic hardware to end-to-end solutions, and an online store.

If you want to get started now, Alpha Micro has a variety of offerings that can help developers explore the world of Sigfox connectivity and services.

Perhaps the most immediately accessible is the eRIC-SIGFOX-USB dongle. It has a USB connector, a Sigfox modem, SMA antenna connector, and operates at 868MHz. It can be controlled using simple AT commands, making it an easy way to get started with Sigfox. Emphasising the extreme simplicity of the expected end applications for Sigfox connectivity, the dongle can upload up to 140 messages with 12byte payloads and download up to four 8byte payloads per day.

This Sigfox dongle uses a radio module from the eRIC family, which also includes solutions for LoRa and easyRadio connectivity. This means that you can experiment with Sigfox using a dongle, perhaps then move to integrating the eRIC module onto your own board in prototyping, and yet still have options to switch to other connectivity solutions if necessary. This should cut development risks and costs.

ON Semiconductor offers other ways to explore Sigfox services.

It has just launched a programmable RF transceiver System in Package (SIP) that integrates an RF System-on-Chip (SoC) and all the related components, including the TCXO, in one package. The AX-SIP-SFEU SIP is just 7x9x1mm, much smaller than module-based approaches. The part offers very low power consumption, with standby mode consuming 500mA, sleep mode 1.3mA, and deep sleep mode 100nA.

For designs which don’t need such high levels of integration, ON Semiconductor offers its AX−SFEU ultra-low power modules. Like the SIP, these parts have both up- and downlink functions, and can be driven using AT commands over a logic-level RS232 UART. The module comes in two versions: one with a 50ohm antenna port and the other with an onboard chip antenna. The modules already have Sigfox certification.

As before, if the prototyping phase goes well and you need greater integration, ON Semiconductor also offers single-chip Sigfox solutions. The AX-SFEU-1-01 and AX-SFEU-API-1-01 chips include an ultra-low power microcontroller and a transceiver and are programmed and certified to act as a Sigfox node.

The -API-1-01 variant can also be programmed to run user software. There’s a library of software available through an API, an IDE, and the MCU has 64Kb of Flash, more than 32Kb of which is available for the user. The MCU also has peripherals such as an SPI bus master, UART, GPIOs, RTC, ADC, DAC and a temperature sensor, all of which are accessible to the user’s programs.

The radio transceiver on the chip runs the Sigfox protocol in hardware, minimising power consumption and the overhead on the MCU. The user programmable version of the device can also run other sub-1GHz radio stacks, again making it possible to experiment with Sigfox connectivity while keeping your radio options open.

If you need them, Alpha Micro also stocks RF cables and ISM-band antennas to work with these Sigfox parts.