W79E548 Datasheet, PDF (25/79 Pages) Winbond – 8-BIT MICROCONTROLLER

W79E548/W79L548
TF2:
Timer 2 overflow flag: This bit is set when Timer 2 overflows. It is also set when the count is
equal to the capture register in down count mode. It can be set only if RCLK and TCLK are
both 0. It is cleared only by software. Software can also set or clear this bit.
EXF2: Timer 2 External Flag: A negative transition on the T2EX pin (P1.1) or timer 2 overflow will
cause this flag to set based on the CP / RL2 , EXEN2 and DCEN bits. If set by a negative
transition, this flag must be cleared by software. Setting this bit in software or detection of a
negative transition on T2EX pin will force a timer interrupt if enabled.
RCLK: Receive Clock Flag: This bit determines the serial port 0 time-base when receiving data in
serial modes 1 or 3. If it is 0, then timer 1 overflow is used for baud rate generation, otherwise
timer 2 overflow is used. Setting this bit forces timer 2 in baud rate generator mode.
TCLK: Transmit Clock Flag: This bit determines the serial port 0 time-base when transmitting data in
modes 1 and 3. If it is set to 0, the timer 1 overflow is used to generate the baud rate clock
otherwise timer 2 overflow is used. Setting this bit forces timer 2 in baud rate generator mode.
EXEN2: Timer 2 External Enable. This bit enables the capture/reload function on the T2EX pin if
Timer 2 is not generating baud clocks for the serial port. If this bit is 0, then the T2EX pin will
be ignored, otherwise a negative transition detected on the T2EX pin will result in capture or
reload.
TR2: Timer 2 Run Control. This bit enables/disables the operation of timer 2. Clearing this bit will
halt the timer 2 and preserve the current count in TH2, TL2.
C / T2 : Counter/Timer Select. This bit determines whether timer 2 will function as a timer or a counter.
Independent of this bit, the timer will run at 2 clocks per tick when used in baud rate generator
mode. If it is set to 0, then timer 2 operates as a timer at a speed depending on T2M bit
(CKCON.5), otherwise it will count negative edges on T2 pin.
CP / RL2 : Capture/Reload Select. This bit determines whether the capture or reload function will be
used for timer 2. If either RCLK or TCLK is set, this bit will be ignored and the timer will
function in an auto-reload mode following each overflow. If the bit is 0 then auto-reload will
occur when timer 2 overflows or a falling edge is detected on T2EX pin if EXEN2 = 1. If this
bit is 1, then timer 2 captures will occur when a falling edge is detected on T2EX pin if
EXEN2 = 1.
Timed 2 Mode Control
Bit:
7
6
5
4
3
2
1
0
-
-
-
-
T2CR
-
-
DCEN
Mnemonic: T2MOD
Address: C9h
T2CR: Timer 2 Capture Reset. In the Timer 2 Capture Mode this bit enables/disables hardware
automatically reset Timer 2 while the value in TL2 and TH2 have been transferred into the
capture register.
DCEN: Down Count Enable: This bit, in conjunction with the T2EX pin, controls the direction that
timer 2 counts in 16-bit auto-reload mode.
Timer 2 Capture LSB
Bit:
7
6
5
4
3
2
1
0
RCAP2L.7 RCAP2L.6 RCAP2L.5 RCAP2L.4 RCAP2L.3 RCAP2L.2 RCAP2L.1 RCAP2L.0
Mnemonic: RCAP2L
Address: CAh
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Publication Release Date: December 12, 2005
Revision A1