Atmel 8051 User Manual

Common Features Description
2-107 Atmel 8051 Microcontrollers Hardware Manual
4316B–8051–02/04
Reset Value = 0000 0000b
Bit addressable
Bit
Number
Bit
Mnemonic Description
7 TF2
Timer 2 overflow Flag
Must be cleared by software.
Set by hardware on timer 2 overflow, if RCLK = 0 and TCLK = 0.
6 EXF2
Timer 2 External Flag
Set when a capture or a reload is caused by a negative transition on T2EX pin if EXEN2=1.
When set, causes the CPU to vector to timer 2 interrupt routine when timer 2 interrupt is enabled.
Must be cleared by software. EXF2 doesn’t cause an interrupt in Up/down counter mode (DCEN = 1)
5 RCLK
Receive Clock bit for UART
Cleared to use timer 1 overflow as receive clock for serial port in mode 1 or 3.
Set to use timer 2 overflow as receive clock for serial port in mode 1 or 3.
4TCLK
Transmit Clock bit for UART
Cleared to use timer 1 overflow as transmit clock for serial port in mode 1 or 3.
Set to use timer 2 overflow as transmit clock for serial port in mode 1 or 3.
3 EXEN2
Timer 2 External Enable bit
Cleared to ignore events on T2EX pin for timer 2 operation.
Set to cause a capture or reload when a negative transition on T2EX pin is detected, if timer 2 is not used to clock the
serial port.
2TR2
Timer 2 Run control bit
Cleared to turn off timer 2.
Set to turn on timer 2.
1C/T2#
Timer/Counter 2 select bit
Cleared for timer operation (input from internal clock system: F
CLK PERIPH
).
Set for counter operation (input from T2 input pin, falling edge trigger). Must be 0 for clock out mode.
0CP/RL2#
Timer 2 Capture/Reload bit
If RCLK=1 or TCLK=1, CP/RL2# is ignored and timer is forced to auto-reload on timer 2 overflow.
Cleared to auto-reload on timer 2 overflows or negative transitions on T2EX pin if EXEN2=1.
Set to capture on negative transitions on T2EX pin if EXEN2=1.
76543210
SMOD1 SMOD0 - POF GF1 GF0 PD IDL

Atmel 8051 Specifications

General

Brand	Atmel
Model	8051
Category	Microcontrollers
Language	English