184 Chapter 10
Scan test
est utility test environment
est utility test environment
est is started on the teststation and is located in /spp/bin/est. The user
has the option of either starting up a user interface or having the est
utility run a script.
est works on one node at a time by sending scan instructions and data
and receiving the results over the diagnostic ethernet connection.
Since est has to communicate closely with the Utilities board, no other
diagnostic can be run at the same time. Also, while est is moving data
through the scan rings, the operating system can not be running.
est works on the JTAG scan rings throughout the system. Tests
provided are:
• Ring (test command r)—Moves data through the scan rings to make
sure the rings are connected and that basic scan hardware is
operational.
• Dc connectivity (command d)—Checks that wires on the boards
between scan devices are intact (no shorts or opens).
• Ac connectivity (command a)—Examines wires on the boards. Ac
tests look for timing problems between parts at full speed. If dc
connectivity patterns passed, but ac connectivity failed, the failure is
bound to be timing related.
• Gate array (command g)—Executes scan tests internal to selected
arrays. When these tests fail, the array usually has to be replaced.
These tests are listed in the order in which they should normally be run.
Control of utility board
To prevent unexpected shutdowns from hardware that is sensitive to
scan operations, est takes control of a power signal on the Utility board.
To control this signal, est must freeze some of the bits of the Utilities
board. Therefore, when est starts, it automatically performs the
id_verify operation and ring test (command r) on the Utility Ring
(ring 22). est then locks the bits to control the power signal. If the user
needs to run the id_verify or ring test function, scan operations will
occur in all scan rings except the Utility Ring.
