Sundance-spas ST201 Manuel d'utilisateur télécharger pdf (Page 43)

Sundance Technology ST201 PRELIMINARY draft 2

I/O REGISTERS

The host interacts with the ST201 mainly through slave registers, which occupy 128 bytes in the host sys-

tem’s I/O space, memory space, or both. Generally, registers are referred to as “I/O registers”, implying

that the registers may in fact be mapped and accessed by the host system in memory space. I/O registers

must be accessed with instructions that are no larger than the bit-width of that register. For instance, even

though the FramesWithExcessiveDeferral, FramesLostRxErrors, and FramesWithDeferredXmission regis-

ters all appear in the same double word at offset 78, it is not legal to read all three registers with a single

32-bit I/O read instruction.

The ST201 I/0 register layout is show in Figure 11.

1 2 ... 38 39 40 41 42 43 44 45 46 47 48 ... 144 145

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Sundance-spas ST201 Manuel d'utilisateur Page 43