Power-over-Ethernet (PoE) is an emerging new technology that enables delivery of data and power to internet appliances over existing CAT-5 Ethernet cables. PoE is rapidly gaining in popularity with manufacturers and end users of devices such as VoIP phones, wireless access points, security cameras and point-of-sale terminals. PoE is governed by the standards defined in the recently ratified IEEE802.3af standard.

This article describe how USB device indicate its speed. You can find here solutions some vendors and circuits devices with pull up resistor.

DCF77 is a radio station that continuously broadcasts accurate time information, which you can receive and decode in your application.

RD2 Kit is a simple and cheap development Kit for quick development of new applications and learning the C language. The Kit contains a T89c51RD2 microcontroller and basic peripherals.