Bit−Addressable SFRs

3.3 Bit−Addressable SFRs

All SFRs that have addresses divisible by eight (i.e., 80H, 88H, 90H, 98H, etc.) are bit-addressable. This means that individual bits of these SFRs can be set or cleared using the SETB and CLR instruction.

Note:

The SFRs whose names appear BOLD in Table 3−1 are SFRs that may be accessed via bit operations; these also happen to be the first column of SFRs on the left side of the chart. The other SFRs cannot be accessed using bit operations such as SETB or CLR.

3.4 SFR Types

Four of the SFRs are related to the I/O ports. The MSC1210 has four I/O ports of eight bits, for a total of 32 I/O lines. Whether a given I/O line is high or low, and the value read from the line, is controlled by these SFRs. Refer to Section 15.1 for the detailed control of the port usages.

SFRs control the operation or the configuration of the MSC1210. For example, TCON controls the timers and SCON controls the serial port.

The remaining SFRs can be thought of as auxiliary SFRs, in the sense that they do not directly configure the MSC1210, but obviously the MSC1210 can- not operate without them. For example, once the serial port has been config- ured using SCON0, the program can read or write to the serial port using the SBUF0 register.

3-4

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Texas Instruments MSC1210 manual Bit−Addressable SFRs, SFR Types