Dot LED matrix is great for displaying various type information including graphical, text, and animation. They usually are big enough to see from a distance and bright to be visible at day and night. Embedded-lab built LED matrix display board which uses five 8×8 LED modules that makes pretty decent 8×40 display.

The display is clocked using PIC16F1847 microcontroller. Of course MCU doesn’t have enough I/Os to drive 320 LEDs. For this a cascading shift registers 74HC595 are used. One for every matrix module column. The rows are controlled with single ULN2803 which sinks LED outputs. Messages can be sent via serial interface using 8×5 byte array totaling the 320 bits. Each bit represents weather corresponding LED is ON or OFF. Received data is stored in to EEPROM memory, so after display powerup it automatically loads saved data and starts displaying without need of computer.

We use remote controls pretty intensively at home. They are great to control devices within your sight without moving a muscle. Well you still need to move your thumb… Anyway there are some remote control commands that are needed right away. Imagine situation when your phone rings and you want to mute TV so you could talk. It takes some effort to find remote, find right button and click it. In that time phone can stop ringing.

TO avoid situations like that, asgard built a rapper – a device which is able to record and repeat remote control sequence once triggered. In order to activate it, all is needed to hammer your knuckles on the table. This activates piezo transducer and device sends IR commands. Rapper is based on tiny PIC12F510 microcontroller which uses TSOP34836 IR receiver for recording IR commands from any remote control. Asgard wanted to make it as a gift so designed nice enclosure which he intends to laser cut.

Wristwatches are interesting areas to experiment and find something new. Each hobby design shows some crazy ideas. Matseng also decided to give a try and made pretty interesting wristwatch. It is based on PIC16F1824 microcontroller that is powered by CR1216 lithium coin cell. Practically there is nothing special about this when looking at schematics. PIC simply drives 12 LEDs that are positioned in circle. Resistive touch sensor activates time display by blinking LEDs. First blink shows hours and second minutes.

Probably most awesome part in this project is the way how watch is assembled. It is literally sandwiched using three PSBs. Top PCB holds LEDs, resistive touch sensor, microcontroller and other minor stuff. Middle PCB serves as battery holder/spacer while bottom holds battery positive pole.

BLDC (BrusheLess Direct Current) motors are used in many areas. Few that come in to the head are PC hard drive drum spinners, RF flying models like quadcopters, robots. The fact is that these motors give high torque over lower weight and size. Don’t require contacting brushes that wear out during time. The only downside is that in order to run and control BLDC you need some electronics to do this. Steven Keeping has published pretty informative article on how typical BLDC motor driving set up looks like. His example is based on PIC microcontroller, but practically any MCU can be used.

In order to drive BLDC motor you need feedback information of current shaft position. This is needed to know which motor stator coil to energize next. Motor position usually is read by using Hall sensors. Such loop configuration allows driving motor at constant precise speed and high torque. I really encourage considering using brushless motors over conventional DC motors as they are more reliable, more energy efficient as there is no mechanical contact on moving shaft -especially when there is no problem to implement electronic control part.