Sundance Spas ST201 manual Registers

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.

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