int e l 1.11 8052AH SPECIAL FUNCTION REGISTERS Symbol Position Name and Significance TF2 T2CON.7 Timer 2 overflow flag set by a Timer 2 overflow and must be cleared by software. TF2 will not be set when either RCLK = 1 or TCLK = 1. EXF2 T2CON.6 Timer 2 external flag set when either a capture or reload is caused by a negative transition on T2EX and EXEN2 = 1. When Timer 2 interrupt is enabled, EXF2 = 1 will cause the CPU to vector to the Timer 2 interrupt routine. EXF2 must be cleared by software. RCLK T2CON.5 Receive clock flag. When set, causes the serial port to use Timer 2 overflow pulses for its receive clock in modes 1 and 3.
RCLK = 0 causes Timer 1 overflow to be used for the receive clock. TCLK T2CON.4 Transmit clock flag. When set, causes the serial port to use Timer 2 overflow pulses for its transmit clock in modes 1 and 3. TCLK = 0 causes Timer 1 overflows to be used for the transmit clock. EXEN2 T2CON.3 Timer 2 external enable flag. When set, allows a capture or reload to occur as a result of a negative transition on T2EX if Timer 2 is not being used to clock the serial port. EXEN2 = 0 causes Timer 2 to ignore events at T2EX. TR2 T2CON.2 Start/stop control for Timer 2. A logic 1 starts the timer. C/T2 T2CON.1 Timer or counter select.
(Timer 2) 0 = Internal timer (OSC/12) 1 = External event counter (falling edge triggered). CP/RL2 T2CON.0 Capture/Reload flag. When set, captures will occur on negative transitions at T2EX if EXEN2 = 1. When cleared, auto reloads will occur either with Timer 2 overflows or negative transitions at T2EX when EXEN 2 = 1. When either RCLK = 1 or TCLK = 1, this bit is ignored and the timer is forced to auto-reload on Timer 2 overflow. Timer/Counter2 Control Register (MSB) (LSB) - 196 - TF2 EXF2 RCLK TCLK EXEN2 TR2 C/T2 CP/RLS2