Chip Integrates Sensor Framework

Chip Integrates Sensor Framework

Freescale’s latest sensor platform is smart and can even integrate information from external sensor data behind a standard application programming interface (API). The FXLC95000 Intelligent Motion-Sensing Platform is a sensor hub built on Freescale’s MQX real-time operating system (Fig. 1). This Intelligent Sensor Framework (ISF) is designed to provide a host with sensor data regardless of how the information is being generated. It can be on-chip, off-chip, or virtualized.

Figure 1. Freescale’s FXLC95000 Intelligent Motion-Sensing Platform is a modular system that runs on top of the MQX RTOS. It abstracts on-board and external sensors behind a standard API.

The ISF stack addresses applications and services, not just low level hardware abstraction that would typically be provided by device drivers for a particular device (Fig. 2). It also incorporates device management as well as communications since it is not limited to the initial hardware offering. Sensor fusion allows support for virtual devices based on data provided by physical sensors.

 
Figure 2.The Intelligent Sensor Framework (ISF) stack provides sensor fusion, not just basic sensor interface and management support.

Freescale built the initial Xtrinsic FXLC95000L on a 32-bit Coldfire microcontroller that was combined with a three-axis accelerometer in a 3-mm by 5-mm package. The chip has 128 kbytes of flash and 16 kbytes of RAM. The chip has a lot of headroom. The ISF and the accelerometer support take up a fraction of this storage, so the chip can run applications or support an off-chip host.

The ISF supports Freescale’s other external sensors, including the Xtrinsic MAG3110 three-axis magnetometer as well as future devices, but the platform can work with other sensors. I2C support is part of the package, which is utilized by a range of existing sensors. It’s just a driver, though, so the serial peripheral interface (SPI) or even custom interfaces can be deployed. The FXLC95000L Xtrinsic also has an on-chip 14-bit analog-to-digital converter (ADC).

Developers can start with Freescale’s FXLC95000L prototyping board, which includes the Xtrinsic MAG3110 three-axis magnetometer (Fig. 3). A virtual compass is provided with the software support.

 
Figure 3. The FXLC95000 prototyping board includes an Xtrinsic MAG3110 three-axis magnetometer.

Sensor fusion is hot (see Sensor Fusion For Play And Profit), and Freescale is taking an open, modular approach. Providing a standard interface to sensors allows designers to hide any kind of sensor behind the API. It allows the creation of hardware-independent software that can take advantage of the latest microelectromechanical systems (MEMS) sensors when they become available.

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