Music on the wireless

07 September 2010

The Audivo M-Remote employs RF technology that can support continuous playing status info and album artwork
The Audivo M-Remote employs RF technology that can support continuous playing status info and album artwork

Universal controller offers RF, IR, and colour display and uses Nordic 2.4GHz wireless connectivity.

The M-Remote from German custom A/V development company, Audivo, is the first mainstream universal RF remote control platform to complement RF with traditional IR capabilities, and offer a colour (LCD or OLED) display.

By using Nordic Semiconductor's nRF24LE1 2.4GHz SoCs and Gazell RF software protocol, the M-Remote can seamlessly control the latest video and audio wireless streaming devices via bi-directional RF. The device also controls traditional IR-only equipped appliances such as TVs, set-top boxes (STBs), and A/V amps.

The nRF24LE1 is a ULP system-on-chip 2.4GHz transceiver that enables single-chip implementation of wireless applications. The nRF24LE1’s radio is a fully featured nRF24L01+ 2.4GHz transceiver core including Nordic’s proven Enhanced ShockBurst hardware link layer. It delivers true ULP operation with peak currents low enough to run on coin cell batteries. nRF24LE1 integrates an enhanced 8051 mixed signal MCU core featuring fewer clock cycles per instruction than legacy 8051 devices. Most instructions need just one or two clock cycles leading to an average performance improvement of 8X using the MIPS (Million Instructions Per Second) benchmark. This high performance combined with 16kbytes of on-chip flash and 1kbytes of SRAM ensures the processing platform is powerful enough to run both the RF protocol stack and application layer with ease.

A wide range of peripherals and power saving modes support the RF protocol stack. A ULP 32kHz crystal oscillator provides high accuracy timing for low report rate synchronous protocols and a 16MHz RC oscillator provides fast start-up times from idle. The 32kHz oscillator can provide timing accurate enough for higher report rate protocols without requiring an external crystal. A security co-processor enables AES encrypted wireless communication. The nRF24LE1 provides a range of nanoamp and microamp idle modes specifically designed for ULP RF protocol stacks. Further benefits include higher precision protocol timing, lower power consumption and improved co-existence performance.

For the application layer the nRF24LE1 offers a rich set of interfaces and peripherals including an SPI, 2-wire, UART, 12-bit ADC, PWM and an analogue comparator. As such, the nRF24LE1 is the ideal single chip solution for applications including mice, keyboards, remote controls, game controllers, sports/healthcare sensors, toys and active RFID tags.

The M-Remote OEM platform offers both RF and IR and targets consumer electronics (CE) manufacturers of the latest networked A/V devices such as streaming music servers, Internet radios and wireless multimedia centres. These appliances demand more advanced user interfaces than traditional push-button, one-way IR technology can support. RF offers the high-bandwidth, bi-directional wireless connectivity required to support more advanced user interface mechanisms such as scroll wheels, touch-screens, and track-balls.

These are all designed to make it easier and more intuitive for end users to access and enjoy their digital content and services. This includes the ability to browse large libraries of stored music or long lists of Internet radio stations, or have continuous ('live') playing status info (including that usually shown on a front panel but is often too small or too far away for users to be able to see) and graphics (such as album artwork) displayed directly on a remote's display. In addition, RF eliminates the need for IR's line-of-sight access, allowing devices to be controlled through objects and even interior walls (usually up to a range of about 15m and assuming wall building materials do not excessively attenuate RF signals).

In operation, a Nordic nRF24LE1 located in the universal M-Remote communicates with a second nRF24LE1-based module embedded into the A/V networked streaming device using the Nordic Gazell software protocol. The nRF24LE1 utilises a Nordic nRF24L01+ transceiver core and features an up to 2Mbps on-air data rate combined with ultra low power (ULP) operation and advanced power management. The Gazell RF protocol provides features for advanced navigation, background data transfers (for larger files such as album artwork), and advanced pairing schemes, while being able to handle up to five remote devices at the same time. In addition, Gazell is a frequency agile protocol that is highly immune to interference from other 2.4GHz radio sources such as Bluetooth wireless technology and Wi-Fi.

To conserve power, the M-Remote will typically enter an ultra-low power (22µA) standby sleep mode when not in use (after 30 seconds in default mode, or between 10-90 seconds if set by the user). This, however, is all hidden from the end user by the use of an in-built motion sensor that means if the remote is picked up it activates a rapid power up (including the display) in 200ms ready to respond immediately to any user input request. The M-Remote is able to offer over a week of operation before battery recharge.

The fully customisable M-Remote is a complete solution including the remote control handset with integrated rechargeable lithium-ion (Li-ion) battery, charging cradle, host A/V device RF module, IR transmitter for standard devices (optional), API source codes (making it very easy to integrate the M-Remote platform into any modern A/V device), product design support, development kit, automatic pairing, and an optional touch (scroll) wheel. A full touchscreen could also be integrated if required, and multi-room (zone) control is supported.

“After considering several wireless technology potential options – including Bluetooth and Wi-Fi – we identified Nordic’s proven proprietary 2.4GHz solution – with its field-proven Gazell software protocol, fast start-up time, ultra low power consumption, and competitive CE-targeted pricing – as the most suitable wireless connectivity technology for our remote control application,” comments Erich Boehm, Managing Director of Audivo. "We were not RF experts, but by using the Nordic nRF24LE1 with Gazell protocol, the development process was made very straightforward and we were able to focus on our core competence of the overall system and higher level application-only software design while adding little to our overall BOM and accelerating time-to-market. This was critical for us if we were to allow our potential customers enough time to employ our M-Remote platform in products scheduled for release by Christmas this year."

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