National Instruments AT-MIO-64F-5, Руководство пользователя

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Chapter 4 Register Map and Descriptions
© National Instruments Corporation 4-3 AT-MIO-64F-5 User Manual
Register Description Format
The remainder of this register description chapter discusses each of the AT-MIO-64F-5 registers
in the order shown in Table 4-1. Each register group is introduced, followed by a detailed bit
description of each register. The individual register description gives the address, type, word
size, and bit map of the register, followed by a description of each bit.
The register bit map shows a diagram of the register with the MSB shown on the left (bit 15 for a
16-bit register, bit 7 for an 8-bit register), and the LSB shown on the right (bit 0). A square is
used to represent each bit. Each bit is labeled with a name inside its square. An asterisk (*) after
the bit name indicates that the bit is inverted (negative logic).
In many of the registers, several bits are labeled with an X, indicating donÕt care bits. When a
register is read, these bits may appear set or cleared but should be ignored because they have no
significance.
The bit map field for some registers states not applicable, no bits used . Accessing these registers
generates a strobe in the AT-MIO-64F-5. These strobes are used to initiate some onboard event
to occur. For example, they can be used to clear the analog input circuitry or to start a data
acquisition operation. The data is ignored when writing to these registers; therefore, any bit
pattern suffices. Likewise, data returned from a strobe register read access is meaningless.