FMEA error flags are cleared. Any FMEA errors will be reported
as the tests are performed for the first time.
The FMEA testing is done on all enabled keys in the matrix, and
results are reported via the serial interface through a dedicated
status command (page 15). Disabled keys are not tested. The
existence of an error is also reported in normal key reporting
commands such as Report 1st Key, page 15.
Assuming no detect events occur, the real time that elapses
from the start of one sequence of FMEA tests to the start of the
next, i.e. the FMEA sequence time, never exceeds 2s.
Also, since the devices only communicate in slave mode, the
host can determine immediately if the QT has suffered a
catastrophic failure. The QT can also participate in
cross-checking the integrity of the host controller, and even
reset the host if no communications have been heard from it in
a short while (via the LED pin output, page 23).
The FMEA tests performed are:
X drive line shorts to Vdd and Vss
X drive line shorts to other pins
X drive signal deviation
Y line shorts to Vdd and Vss
Y line shorts to other pins
X to Y line shorts
Cs capacitor checks including shorts and opens
Vref test
Other tests incorporated into the devices include:
A test for signal levels against a preset min value (LSL
setup, see Section 5.15, page 23). If any signal level falls
below this level, an error flag is generated.
CRC communications checks on all critical command and
data transmissions.
‘Last-command’ command to verify that an instruction was
properly received.
Loss of communications reset of the host controller.
For those applications requiring it, Quantum can supply sample
FMEA test data on special request.
lQ
8
QT60486-AS R8.01/0105
QUANTUM [ QUANTUM RESEARCH GROUP ]
