Specifications
GAL20VP8
Registered Mode
In the Registered mode, macrocells are configured as dedicated
registered outputs or as I/O functions.
All registered macrocells share common clock and output enable
control pins. Any macrocell can be configured as registered or I/
O. Up to eight registers or up to eight I/Os are possible in this mode.
Dedicated input or output functions can be implemented as sub-
sets of the I/O function.
Registered outputs have eight product terms per output. I/Os have
seven product terms per output.
The JEDEC fuse numbers, including the User Electronic Signature
(UES) fuses and the Product Term Disable (PTD) fuses, are shown
on the logic diagram on the following page.
CLK
Registered Configuration for Registered Mode
- SYN=0.
- AC0=1.
- XOR=0 defines Active Low Output.
- XOR=1 defines Active High Output.
- AC1=0 defines this output configuration.
- AC2=1 defines totem pole output.
- AC2=0 defines open-drain output.
- Pin 1(2) controls common CLK for the registered
outputs.
- Pin 12(14) controls common
OE
for the registered
outputs.
- Pin 1(2) & Pin 12(14) are permanently configured as
CLK &
OE
for registered output configuration.
D
Q
Q
XOR
OE
Combinatorial Configuration for Registered Mode
- SYN=0.
- AC0=1.
- XOR=0 defines Active Low Output.
- XOR=1 defines Active High Output.
- AC1=1 defines this output configuration.
- AC2=1 defines totem pole output.
- AC2=0 defines open-drain output.
- Pin 1(2) & Pin 12(14) are permanently configured as
CLK &
OE.
for registered output configuration.
XOR
Note: The development software configures all of the architecture control bits and checks for proper pin usage automatically.
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