Digi NS9750 - Manual (Page 696)

O v e r v i e w
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Nibble mode
Nibble mode can send a byte of information to the host by sending two nibbles. This
mode operates only in reverse mode.
Figure 97 shows the timing relationship on the port interface.
Figure 97: Nibble mode data transfer cycles
Byte mode
Byte mode sends information to the host over the data lines, at 8 bits per cycle. The
peripheral sets the PtrClk bit high to acknowledge the host.
Figure 98 shows the timing relationship on the port interface.
Figure 98: IEEE 1284 byte mode data transfer cycle