Serial Testing & Digital Design

Micro-Electro-Mechanical Systems (MEMS) are the technology of very small devices. MEMS are made up of components between 1 to 100 micro-meter in size (i.e. 0.001 to 0.1 mm), and MEMS devices generally range in size from 20 micro-meters to a millimeter (i.e. 0.02 to 1.0 mm). They usually consist of a central unit that processes data (the microprocessor) and several components that interact with their surroundings such as micro-mirrors.

The testing of Ethernet-based devices – supporting the 10Base-T, 100Base-TX, and 1000Base-T standards – is defined in the IEEE 802.3-2005 and ANSI X3.263-1995 standards. Support for four test modes is required in the physical layer of the device-under-test (DUT). A disturbing sine wave is required for modes 1 and 4.

2C (or, Inter-Integrated Circuit) is a 2-wire communications bus used to provide connectivity between microchips on printed circuit boards and in embedded systems. Introduced in the 1980s by Phillips, I2C helps to maximize hardware efficiency and circuit simplicity, and is employed in a wide variety of electronic devices.

Since the mid-1970s, the structural testing of loaded printed circuit boards (PCBs) has relied very heavily on the use of the so-called in-circuit “bed-of-nails” technique. This method of testing makes use of a fixture containing a bed-of-nails to access individual devices on the board through test landing sites or pads laid into the copper interconnect, or at other convenient contact points.

The testing of USB devices, hosts, and hubs is carried out according to the requirements of the USB (Universal Serial Bus) Specification and the USB-IF Compliance Program. USB testing requires the use of probes and additional USB devices.