OR3C55-5BA352I datasheet(26/210 Pages) AGERE

26 / 210 page

Lucent Technologies Inc.

Data Sheet

June 1999

ORCA Series 3C and 3T FPGAs

Programmable Logic Cells (continued)

The GSRN signal is only asynchronous, and it sets/

resets all latches/FFs in the FPGA based upon the set/

reset configuration bit for each latch/FF. The set/reset

value determines whether GSRN and LSR are set or

reset inputs. The set/reset value is independent for

each latch/FF. A new option is available to disable the

GSRN function per PFU after initial device configura-

tion.

The latch/FF can be configured to have a data front-

end select. Two data inputs are possible in the front-

end select mode, with the SEL signal used to select

which data input is used. The data input into each

latch/FF is from the output of its associated LUT, F[7:0],

or direct from DIN[7:0], bypassing the LUT. In the front-

end data select mode, both signals are available to the

latches/FFs.

If either or both of these inputs is unused or is unavail-

able, the latch/FF data input can be tied to a logic 0 or

logic 1 instead (the default is logic 0).

The latches/FFs can be configured in three basic

modes:

1. Local synchronous set/reset: the input into the

PFU’s LSR port is used to synchronously set or

reset each latch/FF.

2. Local asynchronous set/reset: the input into LSR

asynchronously sets or resets each latch/FF.

3. Latch/FF with front-end select, LSR either synchro-

nous or asynchronous: the data select signal

selects the input into the latches/FFs between the

LUT output and direct data in.

For all three modes, each latch/FF can be indepen-

dently programmed as either set or reset. Figure 17

provides the logic functionality of the front-end select,

global set/reset, and local set/reset operations.

The ninth PFU FF, which is generally associated with

registering the carry-out signal in ripple mode func-

tions, can be used as a general-purpose FF. It is only

an FF and is not capable of being configured as a latch.

Because the ninth FF is not associated with an LUT,

there is no front-end data select. The data input to the

ninth FF is limited to the CIN input, logic 1, logic 0, or

the carry-out in ripple and half-logic modes.

Key: C = configuration data.

Figure 17. Latch/FF Set/Reset Configurations

DIN

LOGIC 0

LOGIC 1

s_set

s_reset

CLK

SET RESET

LSR

GSRN

CE/ASWE

CLK

SET RESET

LSR

CE/ASWE

CLK

SET RESET

CE/ASWE

DIN

SEL

GSRN

DIN

LOGIC 0

LOGIC 1

DIN

LOGIC 0

LOGIC 1

LSR

GSRN

OR3C55-5BA352I Datasheet(PDF) 26 Page - Agere Systems

OR3C55-5BA352I Datasheet(HTML) 26 Page - Agere Systems

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL