Connecting LED matrix in to modules

LED matrix is a great way to display things. Normally single matrix bloc is quite small. In order to get bigger picture you need to combine multiple modules. The best way is to use shift registers. Will built a modular LED matrix design that makes it easy to combine several 8×8 LED matrix blocks in to bigger one. He used MAX7219 driver chips. They can be interfaced using SPI interfaces. And multiple chips can be daisy-chained. This setup requires few lines to control. Each module has convenient connector which allows quick plug-in many of them in a row. Continue reading

Temperature sensor and storage for embedded projects

Temperature sensor and storage for embedded projects

I2C interface allows connecting multiple devices using two wires. This interface is very popular in sensors, memory chips and IO expanders. R-B designed compact breakout board where he placed MCP9802 temperature sensor and 24LC512 EEPROM. Module is convenient to use as temperature sensor with ability to log values in to near by memory. So if you decide to unplug sensor – history of data goes with you. 512Kbit EEPROM gives enough space for storing data. Digital temperature sensor is capable of measuring temperatures from -55ºC to 125ºC. Prototyping board is designed so it could be easily plugged in to prototyping breadboard. Continue reading

Nice little switch for your next microcontroller project

power toggle switch

When building a microcontroller based project we don’t think much about power switch. Usually this is a simple switch that connects power on and off. More sophisticated designs may require smarter solutions like toggle switch. J.R. Stoner has been playing around with interesting circuit called Powach. This is a standalone toggle power switch with built-in debounce and power LED indicator. Circuit is built using Schmit triggers and P-channel MOSFET. Switch can pass up to 2A of current which is enough in most embedded projects. The switch turns power on practically immediately, while turning off requires longer hols. It prevents from accidental turn off. Great feature. Board is designed to fit in to breadboard, while circuit itself can be a nice piece for your next MCU project. Continue reading