The order of the bits after the 8B/10B encoder is the opposite of the order shown in 8B/10B Valid Characters, because 8B/10B encoding requires bit a0 to be transmitted first, and the GTY/GTYP transceiver always transmits the right-most bit first. To match with 8B/10B, the 8B/10B encoder in the GTY/GTYP transceiver automatically reverses the bit order. The 8B/10B encoder does not support TX_DATA_WIDTH = 80 or 160. TX_INT_DATAWIDTH must be set to 0 (2-byte internal datapath) or 1 (4-byte internal datapath). To match with 8B/10B, the 8B/10B encoder in the GTY/GTYP transceiver automatically reverses the bit order.
The number of bits used by CH*_TXDATA and corresponding byte orders are determined by TX_DATA_WIDTH.
- Only use CH*_TXDATA[15:0] if TX_DATA_WIDTH = 20
- Only use CH*_TXDATA[31:0] if TX_DATA_WIDTH = 40
When the 8B/10B encoder is bypassed and TX_DATA_WIDTH is set to a multiple of 10, 10-bit characters are passed to TX data interface with this format:
- The corresponding TXDATA byte represents the [7:0] bits
- TXDATA[9:8] represents the ninth and eighth bits, respectively