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EP1C6F256I8 参数 Datasheet PDF下载

EP1C6F256I8图片预览
型号: EP1C6F256I8
PDF下载: 下载PDF文件 查看货源
内容描述: 气旋FPGA系列 [Cyclone FPGA Family]
分类和应用: 可编程逻辑时钟
文件页数/大小: 94 页 / 1066 K
品牌: ALTERA [ ALTERA CORPORATION ]
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Preliminary Information  
Cyclone FPGA Family Data Sheet  
addnsub Signal  
The LE’s dynamic adder/subtractor feature saves logic resources by using  
one set of LEs to implement both an adder and a subtractor. This feature  
is controlled by the LAB-wide control signal addnsub. The addnsub  
signal sets the LAB to perform either A + B or A B. The LUT computes  
addition; subtraction is computed by adding the two’s complement of the  
intended subtractor. The LAB-wide signal converts to two’s complement  
by inverting the B bits within the LAB and setting carry-in = 1 to add one  
to the least significant bit (LSB). The LSB of an adder/subtractor must be  
placed in the first LE of the LAB, where the LAB-wide addnsubsignal  
automatically sets the carry-in to 1. The Quartus II Compiler  
automatically places and uses the adder/subtractor feature when using  
adder/subtractor parameterized functions.  
LE Operating Modes  
The Cyclone LE can operate in one of the following modes:  
Normal mode  
Dynamic arithmetic mode  
Each mode uses LE resources differently. In each mode, eight available  
inputs to the LE the four data inputs from the LAB local interconnect,  
carry-in0and carry-in1from the previous LE, the LAB carry-in  
from the previous carry-chain LAB, and the register chain  
connection are directed to different destinations to implement the  
desired logic function. LAB-wide signals provide clock, asynchronous  
clear, asynchronous preset/load, synchronous clear, synchronous load,  
and clock enable control for the register. These LAB-wide signals are  
available in all LE modes. The addnsubcontrol signal is allowed in  
arithmetic mode.  
The Quartus II software, in conjunction with parameterized functions  
such as library of parameterized modules (LPM) functions, automatically  
chooses the appropriate mode for common functions such as counters,  
adders, subtractors, and arithmetic functions. If required, the designer can  
also create special-purpose functions that specify which LE operating  
mode to use for optimal performance.  
Altera Corporation  
11  
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