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USB STEP BY STEP
Many designers with otherwise fine ideas about connecting stuff to their PC resent the virtual disappearance of the trusted RS232 and Centronics ports that were sooo easy to write software for. The successor port called USB is a massive success commercially but feared by many for its complexity when it comes to being used as a gateway to homebrew circuits. In next month’s article we present a step by step guide to getting USB-equipped peripherals to do the things you want to, guiding you through the hardware, a cheap Atmel AVR-USB development board, and software abstractions like libraries, DLLs and HIDs. For starters you will learn how to flash LEDs and read a miniature joystick, based on a library that’s free to use by everyone.
COMPACT TTL-BLUETOOTH MODULE
Laptops, mobile phones and PDAs — you mention it, these days it’s bound to have a Bluetooth interface. USB Bluetooth dongles are available at low prices, which opens the way to using these wireless devices to link your own circuits to a PC. To do so, all you need is the compact TTL-Bluetooth dongle we’ll describe in next month’s edition. Besides the LMX9838 chip with its integrated radio transceiver the board contains just a handful of parts, including a connector for audio applications.
MICROCONTROLLER CONTROLLED DIMMER
This dimmer employs an unusual method for brightness adjustment. The dimmer may be programmed by switching the lamp on and then right off again, whereupon the brightness is increased in small steps. As soon as the desired brightness is achieved, you press the switch again. The next time the lamp is switched on it will light at the desired brightness. This solution is also suitable for dimming a lamp via two switches in a staircase configuration.
The January 2010 issue is publshed on December 12, 2009.
Informative articles
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