Intel 8XC251SP User Manual
8XC251SA, SB, SP, SQ USER’S MANUAL
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Instructions
Instruction mnemonics are shown in upper case to avoid confusion.
When writing code, either upper case or lower case may be used.
When writing code, either upper case or lower case may be used.
Logic 0 (Low)
An input voltage level equal to or less than the maximum value of
V
V
IL
or an output voltage level equal to or less than the maximum
value of V
OL
. See data sheet for values.
Logic 1 (High)
An input voltage level equal to or greater than the minimum value of
V
V
IH
or an output voltage level equal to or greater than the minimum
value of V
OH
. See data sheet for values.
Numbers
Hexadecimal numbers are represented by a string of hexadecimal
digits followed by the character H. Decimal and binary numbers are
represented by their customary notations. That is, 255 is a decimal
number and 1111 1111 is a binary number. In some cases, the letter B
is added for clarity.
digits followed by the character H. Decimal and binary numbers are
represented by their customary notations. That is, 255 is a decimal
number and 1111 1111 is a binary number. In some cases, the letter B
is added for clarity.
Register Bits
Bit locations are indexed by 7:0 for byte registers, 15:0 for word
registers, and 31:0 for double-word (dword) registers, where bit 0 is
the least-significant bit and 7, 15, or 31 is the most-significant bit. An
individual bit is represented by the register name, followed by a
period and the bit number. For example, PCON.4 is bit 4 of the
power control register. In some discussions, bit names are used. For
example, the name of PCON.4 is POF, the power-off flag.
registers, and 31:0 for double-word (dword) registers, where bit 0 is
the least-significant bit and 7, 15, or 31 is the most-significant bit. An
individual bit is represented by the register name, followed by a
period and the bit number. For example, PCON.4 is bit 4 of the
power control register. In some discussions, bit names are used. For
example, the name of PCON.4 is POF, the power-off flag.
Register Names
Register names are shown in upper case. For example, PCON is the
power control register. If a register name contains a lowercase
character, it represents more than one register. For example,
CCAPMx represents the five registers: CCAPM0 through CCAPM4.
power control register. If a register name contains a lowercase
character, it represents more than one register. For example,
CCAPMx represents the five registers: CCAPM0 through CCAPM4.
Reserved Bits
Some registers contain reserved bits. These bits are not used in this
device, but they may be used in future implementations. Do not write
a “1” to a reserved bit. The value read from a reserved bit is indeter-
minate.
device, but they may be used in future implementations. Do not write
a “1” to a reserved bit. The value read from a reserved bit is indeter-
minate.
Set and Clear
The terms set and clear refer to the value of a bit or the act of giving
it a value. If a bit is set, its value is “1;” setting a bit gives it a “1”
value. If a bit is clear, its value is “0;” clearing a bit gives it a “0”
value.
it a value. If a bit is set, its value is “1;” setting a bit gives it a “1”
value. If a bit is clear, its value is “0;” clearing a bit gives it a “0”
value.
Signal Names
Signal names are shown in upper case. When several signals share a
common name, an individual signal is represented by the signal name
followed by a number. Port pins are represented by the port abbrevi-
ation, a period, and the pin number (e.g., P0.0, P0.1). A pound
symbol (#) appended to a signal name identifies an active-low signal.
common name, an individual signal is represented by the signal name
followed by a number. Port pins are represented by the port abbrevi-
ation, a period, and the pin number (e.g., P0.0, P0.1). A pound
symbol (#) appended to a signal name identifies an active-low signal.