16 from 4
Port expansion using 74HC595s
Published in issue 387, March 2009
Not having enough ports on a microcontroller to drive all the functions of a circuit is a commonly-encountered problem. The clever port expansion boards described here offer a solution, and need just four signals from the microcontroller. The first board provides sixteen digital output bits; the second board, equally simple to drive, can be used to interface to a HD44780-compatible LCD module. A C library is available to facilitate using the boards with AVR microcontrollers.
Features * Port expansion from four outputs to sixteen outputs * Additional circuit board to interface to HD44780-compatible LCD using four port pins * Controlled using software SPI emulation with free choice of microcontroller output pins * Boards may be cascaded * Maximum total load on all outputs approximately 70 mA * C library available for AVR microcontrollers to drive port expansion and LCD interface boards
|
Click below to download a PDF copy of this article from Elektor magazine.
Please note. In view of the complexity of international markets, Elektor cannot guarantee the availability of components for this project.
|