SoC Powers Into Low Power RF

Building on Arm’s 32bit RISC Cortex-M3 microcontroller with on-chip SRAM and Flash memory, ADuCRF101 SoC from Analog Devices, ADI, integrates all RF transmit and receive functions, data conversion and processing elements required to deliver a fully programmable radio.

The core 32bit Arm RISC machine delivers up to 1.25 Dhrystone MIPS peak performance and has a flexible 14 channel DMA controller with 128KB of non-volatile Flash/EE and 16KB of SRAM.

ADuCRF101 is designed for a range of remote, battery powered wireless sensor network applications, including utility meters, medical telemetry systems, building automation, asset tracking and security systems, to simplify embedding RF in wireless sensor networks. The ultra-low power solution also features a 12bit, 1Msps ADC and ISM band radio transceiver.

“By combining converter technology, low power 32 bit processing, on-chip memory and high performance RF communications in a single 9×9mm package,” comments ADI’s Converter Group Marketing & Applications Director James Caffrey, “the ADuCRF101 provides a radio SoC at a performance level not previously available to battery powered WSN applications. By delivering a solution based on an Arm Cortex-M3, combined with evaluation hardware and software tools, the Analog Devices platform simplifies design and reduces development time for our customers who are designing wireless data acquisition products.”

ADuCRF101 extends ADI’s precision analogue microcontroller portfolio that now includes an ultra-low power device based on the Cortex-M3 to support demanding design requirements for remote sensing and measurement. Notably, ADI runs the on-line EngineerZone for design engineers, an open technical support forum where they can ask questions, share knowledge and search for information on ADI’s precision analogue microcontrollers.

ADuCRF101 is said to lower power in a wide range of applications, enabled by the power efficiency of the Arm processor. The device operates directly from a 3.6V battery and is specifically designed for low power operation using an autonomous packet handler to minimise system current consumption during wireless communications. The network range and coverage of the ADuCRF101 radio SoC is well suited to applications where data must be captured, measured and transmitted quickly in noisy environments without taxing battery life.

“With the ADuCRF101 radio SoC,” explains Ronn Kliger, ADI’s Energy Group Director, “ADI now gives energy metering customers the option of designing with their own processor alongside ADI’s ISM band transceivers or choosing a fully integrated SoC. The new device is an important addition to our energy portfolio, which includes products ranging from single and polyphase metering ICs to a variety of integrated RF transceivers. ADuCRF101 also delivers a single chip communications solution for the challenging requirements of battery powered gas, water and heat meters.”

For medical patient monitoring systems, a wireless Holter or telemetry monitor worn by the patient needs to be small, operate at low power for extended battery life, and deliver the performance level to sustain uninterrupted communication of the patient’s vital signs. The ADuCRF101, says ADI, enables these applications and also provides a platform on which patient monitoring outside the hospital environment can be carried out.

The ADuCRF101’s Cortex-M3 core provides the high integration to support a growing array of sensing and measurement functions. It features serial downloading and debugging, a wake-up timer with RC oscillator and an optional external watch crystal, a 16MHz oscillator with an eight way programmable divider. The integrated RF transceiver provides a combination of advanced interference blocking performance with very low receive and transmit currents, allowing more robust operation in urban environments where signal interference has to be contented with.

The SoC solution’s 431~464MHz and 862~928 MHz UHF transceiver is based on ADI’s ADF7023 device, a low power, highly integrated 2FSK/GFSK/OOK transceiver that covers the worldwide license-free ISM bands at 433, 868 and 915MHz. It is suitable for circuit applications that operate under the European ETSI EN300-220, the North American FCC (Part 15), the Chinese short range wireless regulatory standards or other similar regional standards. Data rates of 1~300kbps are supported.

ADuCRF101 comes in 9x9mm LFCSP packaging and operates from an on-chip oscillator generating an internal 16MHz high frequency clock, routed through a programmable clock divider from which the MCU core clock operating frequency is generated. The SOC also integrates a range of on-chip peripherals configured under microcontroller software control according to the application.

The ADC comprises six single ended inputs for ratio metric measurements on external sensors which can be powered temporarily from the internal LDO for the measurements. An internal battery monitor channel is also available.

Designed specifically for battery powered applications where low power operation is critical, ADuCRF101 can be configured in normal operating mode consuming just 300µA/MHz or in different low power modes under direct program control, including hibernate – internal wake-up timer active – which consumes just 1.6µA. In hibernate mode, peripherals such as external interrupts, UHF transceiver and wake-up timer can wake the device, enabling operation in an ultra-low power operating mode and still responding to active radio communication events, approximately 14mA with UHF receiver on. A non-retain state mode is also provided, consuming as little 680nA. In this mode, external interrupts can wake up the part.

On-chip factory firmware supports in-circuit serial download via the UART interface. Non-intrusive emulation and in-circuit download is supported via serial wire and both these features are incorporated in ADI’s low cost development system. The device operates over 1.8~3.6V in temperatures of -40~+85°C.

The new suite of development tools from ADI for the ADuCRF101 include MiniKit evaluation boards with matching antennae, an emulator and a local communication InterfaceBoard for serial wire program download and debug support. There are also ADuCRF101 specific compilers, as well as CMSIS, Cortex Microcontroller Software Interface Standard, compliant software libraries to support all peripherals and a power/battery life calculator and RF low level drivers and evaluation tools.

The ADuCRF101 radio SoC supports the Dash7 coalition of organisations promoting the standard for versatile wireless sensor networks at 433MHz, based on ISO 18000-7. The device additionally boasts long range, good penetration and low power and also supports 802.15.4 based networks.