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GAL20LV8ZD 数据表(PDF) 3 Page - Lattice Semiconductor |
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GAL20LV8ZD 数据表(HTML) 3 Page - Lattice Semiconductor |
3 / 18 page Specifications GAL20LV8ZD 3 The following discussion pertains to configuring the output logic macrocell. It should be noted that actual implementation is accom- plished by development software/hardware and is completely trans- parent to the user. There are three global OLMC configuration modes possible: simple, complex, and registered. Details of each of these modes is illustrated in the following pages. Two global bits, SYN and AC0, control the mode configuration for all macrocells. The XOR bit of each macrocell controls the polarity of the output in any of the three modes, while the AC1 bit of each of the macrocells controls the in- put/output configuration. These two global and 16 individual archi- tecture bits define all possible configurations in a GAL20LV8ZD. The information given on these architecture bits is only to give a better understanding of the device. Compiler software will trans- parently set these architecture bits from the pin definitions, so the user should not need to directly manipulate these architecture bits. Software compilers support the three different global OLMC modes as different device types. Most compilers also have the ability to automatically select the device type, generally based on the register usage and output enable (OE) usage. Register usage on the device forces the software to choose the registered mode. All combina- torial outputs with OE controlled by the product term will force the software to choose the complex mode. The software will choose the simple mode only when all outputs are dedicated combinatorial without OE control. For further details, refer to the compiler soft- ware manuals. When using compiler software to configure the device, the user must pay special attention to the following restrictions in each mode. In registered mode pin 2 and pin 16 are permanently configured as clock and output enable, respectively. These pins cannot be con- figured as dedicated inputs in the registered mode. In complex mode pin 2 and pin 16 become dedicated inputs and use the feedback paths of pin 26 and pin 18 respectively. Because of this feedback path usage, pin 26 and pin 18 do not have the feedback option in this mode. In simple mode all feedback paths of the output pins are routed via the adjacent pins. In doing so, the two inner most pins ( pins 21 and 23) will not have the feedback option as these pins are always configured as dedicated combinatorial output. When using the standard GAL20V8 JEDEC fuse pattern generated by the logic compilers for the GAL20LV8ZD, special attention must be given to pin 5 (DPP) to make sure that it is not used as one of the functional inputs. Output Logic Macrocell (OLMC) Compiler Support for OLMC |
类似零件编号 - GAL20LV8ZD |
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类似说明 - GAL20LV8ZD |
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