Gesture, proximity and ambient lighting Proximity sensing is highly desirable in many IoT end nodes as well as in portable medical and mobile computing products that require human gesture control and detection. Silicon Labs is able to offer a family of 8-bit products supporting infrared (IR)-based proximity control as well as ambient and ultraviolet (UV) light sensing. For example, the Si114x MCU family implements proximity detection using one, two or three LEDs with a range of up to 50 cm, multi-dimensional motion sensing, heart rate/pulse oximetry and cheek detection capabilities. This sensing architecture works in direct sunlight and includes a light sensor capable of sensing light levels up to
in this article (except for the very simple ones, such as UART, SPI and I2C) come with drivers and/or stacks available at no charge from Silicon Labs. For example, Silicon Labs' 8-bit MCUs featuring crystal-less USB come with a full- featured USB driver included in the USBXpress development kit that provides a complete host and device software solution.
MCU Interfaces and the IoT Today's interconnected IoT ecosystem favours IC devices with a wide variety of interfaces since the heterogeneous nature of the embedded marketplace requires these devices to be able to converse in as many "dialects" as possible.
sensors in commercial/industrial applications. Simple control applications are also better suited to 8-bit rather than 32-bit machines, especially if complex real-time I/O manipulation is necessary. Specifically, the 8051 architecture allows fast I/O bit manipulation with concurrent logical operations, which is useful in control applications. These applications are usually very space- and power-sensitive, which also plays to the strengths of 8-bit devices such as the high- speed 8051 MCUs from Silicon Labs. Note that various ARM Cortex-M series devices can also play in these applications, but, given the board area and power and real-time limitations of the systems, an 8-bit machine with a more deterministic execution model will perform better.
Conclusion Today's IoT connected device applications require versatile MCUs capable of addressing complex communication challenges in a multi-protocol environment. A preponderance of MCU interfaces and connectivity technologies must co-exist on the same die simply because the IoT ecosystem is so diverse. RF integration in particular has done an outstanding job of uniting two essential IoT capabilities: ultra-low power and wireless communication. The addition of superior analogue performance enables the creation of wireless sensor nodes requiring very little external support circuitry.
Figure 2: Proximity sensing MCUs integrate sophisticated mixed-signal peripherals, interfaces and drivers
128 kLux. Light sensing technology often requires special packaging features, such as a transparent window around the light sensors. (See Figure 2 for an example of a proximity sensing MCU.)
Stacks and Drivers
Of course, these MCU interfaces require either stacks and/or drivers to enable their quick integration into a system. The interfaces discussed
A significant number of IoT applications are "thin client" in nature. This is what makes them a natural fit for an 8-bit machine with limited flash and on-board RAM. For example, most sensor applications where voltages/currents must be sensed and operated upon and then transmitted upstream are suited to an 8-bit machine. Examples include gas and oxygen sensors in connected home applications and pressure
While 8-bit MCUs may not be the right fit for every IoT connected device application, they are good choices for cost-sensitive applications requiring small packages, small memory footprints, high functional density, determinism and speed of response. The high-performance 8051 8-bit architecture, coupled with the plethora of interfaces available today, provides an ideal solution for many IoT applications.
Silicon Labs |
www.silabs.com
Tom David is Principal Design Engineer, Silicon Labs
CIE electronica 2014
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