Inter-byte clocking allows clock sharing between a clock arriving at a BITSLICE_0 of one nibble and the nibbles in the same position of other bytes (This Figure). Sharing of the input or sample clock is done through CLK_TO_EXT_NORTH(SOUTH) output pins and CLK_FROM_EXT input pins in BITSLICE_CONTROL components of other bytes. Inter-byte clocking is started by setting attributes EN_CLK_TO_EXT_NORTH(SOUTH).
Inter-nibble and inter-byte clocking can be combined to serve all bit slices in an I/O bank with the same clock (see This Figure).
Notes on This Figure.
•Assume that byte_2, lower nibble, RX_BITSLICE_0 is set up as a clock or strobe input.
•Byte_2, upper nibble must be inter-nibble clock-enabled.
•Because the lower nibble of byte_2 is used as clock input, and all nibbles are used in multi-byte setup, for all bytes the lower nibble must supply the clock to the upper nibble for inter-nibble clocking.
•Byte_3, lower nibble, gets a clock from the CLK_TO_EXT_NORTH output of the lower nibble of byte 2 on its CLK_FROM_EXT input.
•The lower byte south (down) of byte_2, lower nibble supplies a clock from the CLK_TO_EXT_SOUTH output to the CLK_FROM_EXT input of the lower nibble of byte 1.
•To reach the lower nibble of byte 0, the CLK_TO_EXT_SOUTH output of byte 1 must be connected to the CLK_FROM_EXT input of the lower nibble of byte 0. A jump over is made inside byte 1 between the CLK_FROM_EXT and CLK_TO_EXT_SOUTH pins. As such, all receivers in all nibbles are configured to receive data from a forwarded version (via inter-byte/nibble) of the strobe sourced from the byte_2 upper nibble.
For all nibbles, inter-nibble clocking must be enabled as listed in Table: Enabling Inter-Nibble Clocking.