Have you wondered how your tablet still powers up instantly after weeks of being in standby? How about your Bluetooth headset and/or activity monitor automatically turning off when not in use? Extending time between charges in portable consumer devices can be a key differentiating value proposition, and engineers designing these devices have an incessant desire to squeeze out every bit of battery power.
The major power hogs in consumer devices are most often the CPU (like ARM®, x86 MPU, etc.), fans, backlit touch screens and other peripheral devices. Using an “always on” ultra- low-power system controller can significantly reduce power consumption on portable devices. These controllers can monitor user stimuli and vital system parameters like battery health, temperature and more, while the main processor and peripherals are turned off. The microcontroller can “wake up” the system based on a user input, or on a fault condition that requires CPU intervention. The ultra-low-power MSP430™ microcontroller, with < 100uA/MHz active currents, < 40nA standby currents and 5us wake-up times, provides a great platform to develop an “always on” system controller solution for portable battery powered products. The MSP430 microcontroller is so low power that it is widely used in energy harvesting applications such as wireless sensors, RF tags, and medical devices where RF, body heat, etc., serve as renewable power sources.
As an “always on” system controller, the MSP430 device can be used in five broad areas: Human Machine Interface (HMI), power management, sensor hub, low power wireless and other general functions. In this blog series, we will briefly explore these areas and provide tips and tricks of how a developer can use MSP430 collateral to build portable systems like tablets, handsets, phone accessories, wireless sensors and health and fitness accessories. The exact choice of device for these various applications will depend on the desired level of integration of the various functionalities. The MSP portfolio has more than 400 parts – all built with ultra-low-power architecture, high performance analog and digital peripherals and a complete development ecosystem.
Let’s take a closer look at HMI:
Capacitive Touch I/Os
What if your remote only turned on when gripped, or your keyboard illuminated when a hand approached? How about turning on a switch without really touching it, or simply improving the reliability and aesthetics of your product with a capacitive touch button, rather than a mundane push button?
The capacitive touch IOs on MSP430 microcontrollers offer a low-cost, low-power, glue-less interface to touch sensors for mechanical button replacement and proximity sensing. With 1.8V operation and <1ua average power consumption per button, a MSP430 microcontroller is a great solution to “power ON” battery-powered devices. The MSP430 capacitive touch sense software library is entirely open source, and you can easily customize its behavior as well as integrate it with other system controller applications using SYSBIOS.
In addition to getting started guides, workshops and more, TI has developed hardware and software design collateral for developing a 10-cm proximity solution, grip detection, 45-button keypad and a two-dimensional capacitive touchpad implementation all using a MSP430 Value Line device. Check out the videos below for demos of our 10-cm proximity and 1 uA grip detection solutions. MSP430 microcontrollers can also be paired with a DRV8601/DRV2603 haptic driver to provide enhanced user experience with tactile feedback.
Keyboard control is another use case for MSP430 devices in HMI applications. Tablets are transforming into devices where content can be created rather than just being consumed. Having a keyboard and touchpad is essential to this transition, and several keyboard docks are cropping up in the market.
Keyboards are usually powered by the tablet or a small rechargeable battery built into the keyboard, so low-power operation is critical! MSP430 microcontrollers offer a matrix keyboard solution compliant with both HID over USB and HID over I2C standards. HID over I2C is a new Windows® 8 operating system standard for accessory-to-application processor communication, offering significant power savings relative to HID over USB. MSP430 microcontrollers are one of the first in the market to offer a HID over I2C keyboard solution that offers a 90% power savings in comparison to HID over USB. A complete design guide for MSP430F55xx HID over USB keyboard controller and an overview of advantages of the HID over I2C protocol are available on TI’s website. The MSP430 microcontroller on the keyboard can also be integrated with other functions like battery monitoring, back light illumination, etc.
Optical Touch Screens and Touch Pads
In addition to the collateral mentioned above, we have strategic third parties that have developed optical touch screen, touchpad and low-cost ITO touch screen solutions using MSP430 microcontrollers. Contact your TI sales representative for more information on these solutions.
We’ve got a lot to say, so we decided to turn this topic into a blog series. Be sure to check back in with us next week when we’ll continue our consumer application discussion with details on power management. Join the conversation by posting in the comments section below!