People are always looking for new ways of interaction to computer. So far keyboard and mouse are still the most reliable and common way to do so. Of course touch screen is another wide spread method of user input. All of those require physical touch to device in order to enter info. But there are many areas where we would like to manipulate things from distance. Possible applications could be hazardous areas, wet or other places where it would be better to control things, enter information from distance without touching anything.
Magiciant have been experimenting with ultrasonic radar based user input. All you need is to draw with pen in the air in front of ultrasonic sensor and information is captured in to computer screen. Hardware setup is accessible to anyone because it is based on popular Arduino DUE, four HC-SR04 ultrasonic sensors and four channel MCP6024 buffer amplifier. Other magic is inside software where Fast Fourier transform does quite a job. Out of four ultrasonic sensors only one sends pulses while all four capture reflection. By combining collected information system is able to distinguish objects about 5cm apart and 12um depth. Effective working distance can be up to 3m. Update frame rate may be set from 10Hz to 60Hz.
It is said: “There are 10 types of people in this world, those who understand binary and those who don’t”. If you choose understanding side, then you might want to wear binary wristwatch.
Building such watch is fairly simple and easy, because you only need few components and even simpler code. Elias watch is based on PIC microcontroller which comes in SSOP-20 package. With few difficulties on soldering it to small PCB he had it running. Watch is powered from coin cell battery CR2032. With smart software solution combined with sleep modes this watch can last long. But the main point of wearing this watch to be identified as nerd. I’m not suggesting to replicate this one, but build your own version.
There are tons of ARM development boards that are various sizes shapes and power. But when things turn towards battery operated gear, the lists shrinks down. We expect battery operated and portable electronics part to be small size and include all battery management circuit along with charging and DC/DC conversion. Vsergeev introduces his version of small ARM Cortex-M0 powered board.
He wanted his board to be small size, battery operated (USB as well) and be low price. The board size came out to be 70x43mm, it carries NXP LPC1114FDH28 32-bit ARM Cortex-M0 microcontroller. Additionally there is a 16-Mbit SPI FLASH memory. As mentioned before, board canbe powered from USB (Mini-B) or LiPo battery. Battery can be charged with onboard LiPo charger IC (MCP73831T). There are 4 LEDs on board along with two push buttons and 2 DIP switches. For more IO capability there is also an I2C 8 additional I/O pins expander. So there is total 16 I/Os on header, SWD for flashing and debug and 6 pin UART header that matches popular FTDI adapters for USB to serial feature. Project files are open and accessible on GIT.
There is always a dilemma on how to build an indicator for your next project. There are many options like LCDs, LEDs, VFD. Sometimes one or another is enough, but eventually you want something eye catching and obvious that could be seen from distance. For instance for water meter a dial based display probably is better than LCD. IT can be seen from distance and is informative to tell how mutch water is in tank.
John simply built a LED ring display out of 16 single color LEDs. He needed to use shift register, but he thought that popular 74xx595 chip is very current limited. Total current draw shouldn’t exceed 50mA which is like 2 more powerful LEDs at a time. So he looked for more proper shift register and came op with better one – TLC59282 16-bit shift register which is capable of sinking 30mA on each pin. Neat feature of this chip is that it comes with current setting pin, meaning that you only need single resistor for setting current for all LEDs. This saves space on the board. He wrote a nice demo for PIC microcontroller which goes through several display effects. Once you’ve done playing you can use code snippets for displaying info on it like water level, RPM, speed or what ever you want.