PALCE29M16H-25 Datasheet, PDF (20/22 Pages) Advanced Micro Devices – 24-Pin EE CMOS Programmable Array Logic

AMD
OBSERVABILITY
The PALCE29M16 has the capability for product-term
Observability. When the global-Observe product term is
true, the PALCE29M16 will enter the Observe mode.
This feature aids functional testing by allowing direct ob-
servation of register states.
When the PALCE29M16 is in the Observe mode, the
output buffer is enabled and the I/O pin value will be Q of
the corresponding register. This overrides any OE
inputs.
The procedure for Observe is:
Remove the inputs to all the I/O pins.
Parameter
Symbol
tD
tI/O
Parameter Description
Delay Time
Valid Output
Set the inputs to the user selected Observe
configuration.
The register values will be sent to the correspond-
ing I/O pins.
Remove the Observe configuration from the
selected I/O pins.
Because the Observe command is a product term, any
input to the array can be used to set Observe (including
I/O pins and registers). If I/O pins are used, the observe
mode could cause a value change, which would cause
the device to oscillate in and out of the Observe mode.
Therefore, only dedicated input pins should be used for
the Observe command.
Min
Rec.
Max
Unit
0.5
1.0
5.0
µs
100
500
ns
Input
Pins
I/O Pins
CLK
Pin 1 (2)
Observe Mode
tD
tIO
Observability Waveform
VIH
VIL
VOH
VOL
VIH
VIL
08740G-37
2-346
PALCE29M16H-25