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81080V Datasheet(PDF) 3 Page - Lattice Semiconductor |
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81080V Datasheet(HTML) 3 Page - Lattice Semiconductor |
3 / 26 page Specifications ispLSI 81080V 3 interconnecting the Big Fast Megablocks. Each Big Fast Megablock contains 120 registered macrocells arranged in six groups of 20, a group of 20 being referred to as a Generic Logic Block, or GLB. Within the Big Fast Megablock, a Big Fast Megablock Routing Pool (BRP) interconnects the six GLBs to each other and to 24 Big Fast Megablock I/O cells with optional I/O registers. The Global Routing Plane which interconnects the Big Fast Megablocks has additional global I/Os with optional I/O registers. The 192-I/O version contains 72 Big Fast Megablock I/Os and 120 global I/Os, while the 360-I/O version contains 216 Big Fast Megablock I/Os and 144 global I/Os. Outputs from the GLBs in a Big Fast Megablock can drive both the Big Fast Megablock Routing Pool within the Big Fast Megablock and the Global Routing Plane between the Big Fast Megablocks. Switching resources are pro- vided to allow signals in the Global Routing Plane to drive any or all the Big Fast Megablocks in the device. This mechanism allows fast, efficient connections, both within the Big Fast Megablocks and between them. Each GLB contains 20 macrocells and a fully populated, programmable AND-array with 82 logic product terms. The GLB has 44 inputs from the Big Fast Megablock Routing Pool which are available in both true and comple- ment form for every product term. Up to 20 of these inputs can be switched to provide local feedback into the GLB for logic functions that require it. The 80 general-purpose product terms can be grouped into 20 sets of four and sent into a Product Term Sharing Array (PTSA) which allows sharing up to a maximum of 28 product terms for a single function. Alternatively, the PTSA can be by- passed for functions of four product terms or less. The 20 registered macrocells in the GLB are driven by the 20 outputs from the PTSA or the PTSA bypass. Each macrocell contains a programmable XOR gate, a pro- grammable register/latch/toggle flip-flop and the necessary clocks and control logic to allow combinatorial or registered operation. Each macrocell has two outputs, one output can be fed back inside the GLB to the AND- array, while the other output drives both the Big Fast Megablock Routing Pool and the Global Routing Plane. This dual output capability from the macrocell allows efficient use of the hardware resources. One output can be a registered function for example, while the other output can be an unrelated combinatorial function. Macrocell registers can be clocked from one of several global, local or product term clocks available on the device. A global, local and product term clock enable is also provided, eliminating the need to gate the clock to the macrocell registers. Reset and preset for the macro- cell register is provided from both global and product term signals. The polarity of all of these control signals is selectable on an individual macrocell basis. The macro- cell register can be programmed to operate as a D-type register, a D-type flow-through latch or a T-type flip flop. The 20 outputs from the GLB can drive both the Big Fast Megablock Routing Pool within the Big Fast Megablock and the Global Routing Plane between the Big Fast Megablocks. The Big Fast Megablock Routing Pool con- tains general purpose tracks which interconnect the six GLBs within the Big Fast Megablock and dedicated tracks for the signals from the Big Fast Megablock I/O cells. The Global Routing Plane contains general pur- pose tracks that interconnect the Big Fast Megablocks and also carry the signals from the I/Os connected to the Global Routing Plane. Control signals for the I/O cell registers are generated using an extra product term within each GLB, or using dedicated input pins. Each GLB has two extra product terms beyond the 80 available for the macrocell logic. The first additional product term is used as an optional shared product term clock for all the macrocells within the GLB. The second additional product term is then routed to an I/O Control Bus using a separate routing structure from the Big Fast Megablock Routing Pool and Global Routing Plane. Use of a separate control bus routing structure allows the I/O registers to have many control signals with no impact on the interconnection of the GLBs and Big Fast Megablocks. The I/O Control Bus is split into four quadrants, each servicing the I/O cell control re- quirements for one edge of the device. Signals in the control bus can be independently selected by any or all I/O cells to act as clock, clock enable, output enable, reset or preset. Each Big Fast Megablock has 24 I/O cells. The Global Routing Pool has 144 I/O cells. Each I/O cell can be configured as a combinatorial input, combinatorial out- put, registered input, registered output or bidirectional I/O. I/O cell registers can be clocked from one of several global, local or product term clocks which are selected from the I/O control bus. A global and product term clock enable is also provided, eliminating the need for the user to gate the clock to the I/O cell registers. Reset and preset for the I/O cell register is provided from both global and product term signals. The polarity of all of these control ispLSI 8000V Family Description (Continued) |
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