C Software Modules The experimental Shield presented in the July & August 2014 edition provides a good basis for all kinds of experiments based on an Arduino. Especially for this Shield we developed C-code based on the EFL (Elektor Firmware Library). For each hardware module on the Shield there’s a matching software module—all you have to do is to merge the desired blocks to get a functioning prototype. USB Hub with Legacy RS232 and RS422/485 * Electronics designers often run into a problem with modern computers no longer having the legacy serial interfaces, while many microcontroller circuits rely on them for communication. This handy circuit offers a universal solution: it contains a USB hub with three USB connections, and in addition has two full duplex RS232 and two RS422/485 ports. Universal 40 V/2 A Lab Supply Several lab supplies were published in recent editions, each with its own merits and properties. In the November edition we’ll describe Elektor Labs’ proprietary approach—a microcontroller-controlled circuit that uses both switching and analog sections to combine in a single design essential points such as immaculate output voltage, optimal line response and low dissipation behavior. * due to space constraints this article could not be published in the October 2014 edition.