at40kal ATMEL Corporation, at40kal Datasheet - Page 6

• Manufacturer Part Number: at40kal
• Description: At40kal Military Reprogrammable Fpgas With Freeram
• Manufacturer: ATMEL Corporation

The Busing Network
Table 2. Dual-function Buses
6
Function
Cell Output Enable
RAM Output Enable
RAM Write Enable
RAM Address
RAM Data In
RAM Data Out
Clocking
Set/Reset
AT40KAL
Express
Express
Express
Express
Express
Local
Local
Local
Type
Figure 3 on page 7 depicts one of five identical busing planes. Each plane has three bus
resources: a local-bus resource (the middle bus) and two express-bus (both sides)
resources. Bus resources are connected via repeaters. Each repeater has connections
to two adjacent local-bus segments and two express-bus segments. Each local-bus
segment spans four cells and connects to consecutive repeaters. Each express-bus
segment spans eight cells and “leapfrogs” or bypasses a repeater. Repeaters regener-
ate signals and can connect any bus to any other bus (all pathways are legal) on the
same plane. Although not shown, a local bus can bypass a repeater via a programma-
ble pass gate allowing long on-chip tri-state buses to be created. Local/Local turns are
implemented through pass gates in the cell-bus interface (see following page).
Express/Express turns are implemented through separate pass gates distributed
throughout the array.
Some of the bus resource on the AT40KAL is used as a dual-function resource. Table 2
shows which buses are used in a dual-function mode and which bus plane is used. The
AT40KAL software tools are designed to accommodate dual-function buses in an effi-
cient manner.
Plane(s)
1 - 5
5
1
2
4
2
1
5
Horizontal and
Horizontal
Horizontal
Direction
Vertical
Vertical
Vertical
Vertical
Vertical
Vertical
Comments
Bus full length at array edge
Bus in first column to left of RAM block
Bus full length at array edge
Bus in first column to left of RAM block
Buses full length at array edge
Buses in second column to left of RAM block
Bus half length at array edge
Bus half length at array edge
4263B–AERO–06/03