DS80C390_00 Datasheet, PDF (63/155 Pages) Dallas Semiconductor – High-Speed Microcontroller User’s Guide Supplement

Timer 2 Control (T2CON)
7
6
SFR C8h TF2 EXF2
RW-0 RW-0
DS80C390 High-Speed Microcontroller User’s Guide Supplement
5
RCLK
RW-0
4
TCLK
RW-0
3
EXEN2
RW-0
2
TR2
RW-0
1
C/ T2
RW-0
0
CP/ RL2
RW-0
R=Unrestricted Read, W=Unrestricted Write, -n=Value after Reset
TF2
Bit 7
EXF2
Bit 6
Timer 2 Overflow Flag. This flag will be set when Timer 2 overflows from
FFFFh or the count equal to the capture register in down count mode. It must be
cleared by software. TF2 will only be set if RCLK and TCLK are both cleared to
0.
Timer 2 External Flag. A negative transition on the T2EX pin (P1.1) or timer 2
underflow/overflow will cause this flag to set based on the CP/RL2 (T2CON.0),
EXEN2 (T2CON.3), and DCEN (T2MOD.0) bits. If set by a negative transition,
this flag must be cleared to 0 by software. Setting this bit in software or detection
of a negative transition on the T2EX pin will force a timer interrupt if enabled.
CP/ RL2
1
1
0
0
0
EXEN2
0
1
0
1
X
DCEN
X
X
0
0
1
RESULT
Negative transitions on P1.1 will not affect this bit.
Negative transitions on P1.1 will set this bit.
Negative transitions on P1.1 will not affect this bit.
Negative transitions on P1.1 will set this bit.
Bit toggles whenever timer 2 underflows/overflows
and can be used as a 17^th bit of resolution. In this
mode, EXF2 will not cause an interrupt.
RCLK
Bit 5
TCLK
Bit 4
Receive Clock Flag. This bit determines the serial port 0 timebase when
receiving data in serial modes 1 or 3.
0 = Timer 1 overflow is used to determine receiver baud rate for serial port 0.
1 = Timer 2 overflow is used to determine receiver baud rate for serial port 0.
Setting this bit will force timer 2 into baud rate generation mode. The timer
will operate from a divide by 2 of the external clock.
Transmit Clock Flag. This bit determines the serial port 0 timebase when
transmitting data in serial modes 1 or 3.
0 = Timer 1 overflow is used to determine transmitter baud rate for serial port 0.
1 = Timer 2 overflow is used to determine transmitter baud rate for serial port 0.
Setting this bit will force timer 2 into baud rate generation mode. The timer
will operate from a divide by 2 of the external clock.
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