Bit swapping is the swapping of the bits within a byte. TheMCS,EXO, andTEK PROM file
formats are always bit swapped. TheHEX file format can be bit swapped or not bit
swapped, depending on user options.The bitstream files (BIT,RBT, andBIN) are never bit
swapped.
因此ISE输出的Bit文件和Bin文件,可以看到同步字节是 0xAA 0x99 0x55 0x66
Traditionally, in SelectMAP x8 mode, configuration data is loaded one byteper CCLK,
with themost-significant bit (MSB) of each byte presented to the D0 pin.Although this
convention (D0 = MSB, D7 = LSB) differs from many other devices, it isconsistent across all
Xilinx® FPGAs. The bit-swap rule alsoapplies to Spartan-6 FPGA BPI x8 modes
在配置FPGA时,数据时比特调换的,数据的最高位要送到D0脚,因此,发送0xAA (8’b1010_1010)<