Connect - ASSET InterTech

Like close cousins, MicroMaster and ScanWorks™ share an ancestry in JTAG, but each grew up following its own distinctive path. Now, reunited by a corporate acquisition, a more intimate and integrated future for the two technologies bodes well for increased test coverage.

Unlike boundary-scan test processes which utilize a circuit board’s JTAG test access port (TAP), the embedded scan path on the board and the internal boundary-scan resources in chips, MicroMaster is based on processor emulation technology. This test methodology utilizes the JTAG port on the board, and the JTAG or the debug port on the processor to provide test routines and sequences to the CPU. The CPU then performs at-speed test and diagnostic operations on the buses, chips and I/O on the board. Processors supported are Intel, AMD, PowerPC, ARM and Coldfire.

The bottom line for both technologies is the same: they deliver extensive non-intrusive test coverage. And, taken together, the test coverage they provide far exceeds that which they could achieve on their own.

What is MicroMaster?

MicroMaster takes control of a processor upon reset and prevents it from running boot code. It then can direct the CPU to assert routines on any addressable device and perform bus, memory and I/O tests, verifying or diagnosing each device as well as its interconnects to the PCB. Buses can be validated at-speed, the core logic in devices can be functionally tested and the structural integrity of non-boundary-scan devices can be verified.

In addition, MicroMaster can run traditional boundary-scan tests to increase the structural test coverage on a PCB. MicroMaster supports Serial Vector Format (SVF) files, as does ScanWorks. As a result, during test execution, both boundary-scan and processor emulation tests and diagnostics can be run together as an automated sequence.

MicroMaster can be deployed with a wide range of I/O test cards in the system’s 16-slot I/O Emulation Unit. These cards generate input signals and measure output signals for all types of standard and custom-developed I/O circuits. The closed-loop feedback provided by MicroMaster can be performed very quickly and the diagnostics generated are extensive. The full I/O path is tested all the way to the external connector. I/O cards are available to test the following: keyboard, mouse, IrDA, serial port, parallel port, USB, Firewire IEEE 1394, Ethernet, SCSI, IDE, SATA, video, LCD checker, audio, modem, battery simulator, analog I/O, digital I/O and a prototyping card.

The test executive that comes with MicroMaster provides functionality for a wide range of applications, such as board design debug, manufacturing test and debug, and field returns debug. The executive’s capabilities can be focused on the objectives specific to each of these applications. For example, in a board design debug application, the test executive’s interactive mode of operation is particularly useful because it features tools for directly modifying and reading device registers and memory locations without developing tests or other routines. But, in a manufacturing application, the technician or operator is probably only interested in a pass/fail result. For these applications, MicroMaster’s test executive has a fully-automated mode that can execute a suite of pre-scripted tests and output simple pass/fail information.

Since its introduction to the marketplace, MicroMaster has demonstrated its value in a number of ways. Here are just a few:

Besides extending the test coverage of ScanWorks’ boundary-scan-based testing, MicroMaster can also expand the test coverage possible with in-circuit testers (ICT) and manufacturing defect analyzers (MDA).

MicroMaster overcomes some of the deficiencies of ICT and MDA testing which come about when physical access for probes is not available. This is often the case when ball grid array (BGA) device packages are present or when the circuit board contains multiple layers with hidden VIAs. Like ScanWorks, MicroMaster does not rely upon physical access. As a result, it can extend the test coverage obtained by ICT and MDA testers.

In addition, ICT and MDA are impractical for performing functional tests on complex semiconductors because a vast amount of test vectors would have to execute on the device to fully test its core logic. The non-intrusive MicroMaster is able to perform complex functional testing on devices, as well as at-speed testing of bus terminations and differential buses.

MicroMaster can provide a fast functional test prior to system-level test. Typically, this allows for key devices and buses on the circuit board to be verified at a stage much earlier than system test, reducing the manufacturing process’s overall costs. For example, a MicroMaster fast functional test suite might check power to the board, establish access to the CPU, take control of the CPU and then set up and perform tests on all addressable devices on the board.

MicroMaster overcomes some of the deficiencies of ICT and MDA testing which come about when physical access for probes is not available.

MicroMaster is aptly suited to debugging dead boards because, unlike most functional tests, the board doesn’t need to be booted up in order to be tested and diagnosed by MicroMaster. For example, another type of functional test might determine that the board has a dead terminal on it, but that dead terminal could be practically anywhere on the board’s buses or devices. MicroMaster can take control of the CPU without it booting up and test all devices and buses, reporting detailed diagnostic information, including the exact location of dead terminals.

GFI simplifies fault diagnosis by taking advantage of a graphical block diagram of the board to indicate any failed components. Each block on the block diagram can have any number of device-level tests associated with it. If a block fails any of its associated tests, it is highlighted on the block diagram and additional guidance is provided to the technician in a results window.

MicroMaster is one of the fastest methods available for performing in-system programming (ISP) on flash memory and EEPROM devices. This makes MicroMaster particularly well suited to board manufacturing operations and high-volume firmware upgrades. Depending on the type of flash memory device and the way it is implemented on the circuit board, programming times can be less than 10 seconds per megabyte.

Now that MicroMaster and ScanWorks are together under the same corporate umbrella, the possibilities for further integration of boundary-scan and processor emulation test and diagnostics are exceedingly diverse and very exciting. Ultimately, this trend will be propelled by only one thing – greater and greater levels of test coverage. And that will be to the benefit of ScanWorks and MicroMaster users.