AT89LP51 Atmel Corporation, AT89LP51 Datasheet - Page 52

• Manufacturer Part Number: AT89LP51
• Manufacturer: Atmel Corporation

Specifications of AT89LP51

• Flash (kbytes): 4 Kbytes
• Max. Operating Frequency: 20 MHz
• Cpu: 8051-1C
• Max I/o Pins: 36
• Uart: 1
• Sram (kbytes): 0.25
• Eeprom (bytes): 256
• Self Program Memory: IAP
• Operating Voltage (vcc): 2.4 to 5.5
• Timers: 3
• Isp: SPI
• Watchdog: Yes

12.1
Table 12-3.
Table 12-4.
52
T2CON Address = 0C8H
Bit Addressable
Bit
Symbol
TF2
EXF2
RCLK
TCLK
EXEN2
TR2
C/T2
CP/RL2
T2MOD Address = 0C9H
Not Bit Addressable
Symbol
T2OE
DCEN
Bit
Timer 2 Registers
AT89LP51/52
TF2
Function
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.
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. EXF2 does not cause an interrupt in up/down counter mode (DCEN = 1) or dual-slope mode.
Receive clock enable. When set, causes the serial port to use Timer 2 overflow pulses for its receive clock in serial port
Modes 1 and 3. RCLK = 0 causes Timer 1 overflows to be used for the receive clock.
Transmit clock enable. When set, causes the serial port to use Timer 2 overflow pulses for its transmit clock in serial port
Modes 1 and 3. TCLK = 0 causes Timer 1 overflows to be used for the transmit clock.
Timer 2 external enable. 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.
Start/Stop control for Timer 2. TR2 = 1 starts the timer.
Timer or counter select for Timer 2. C/T2 = 0 for timer function. C/T2 = 1 for external event counter (falling edge
triggered).
Capture/Reload select. CP/RL2 = 1 causes captures to occur on negative transitions at T2EX if EXEN2 = 1. CP/RL2 = 0
causes automatic reloads to occur when Timer 2 overflows or negative transitions occur at T2EX when EXEN2 = 1. When
either RCLK or TCLK = 1, this bit is ignored and the timer is forced to auto-reload on Timer 2 overflow.
7
Function
Timer 2 Output Enable. When T2OE = 1 and C/T2 = 0, the T2 pin will toggle after every Timer 2 overflow.
Timer 2 Down Count Enable. When Timer 2 operates in Auto-Reload mode and EXEN2 = 1, setting DCEN = 1 will cause
Timer 2 to count up or down depending on the state of T2EX.
–
7
T2CON – Timer/Counter 2 Control Register
T2MOD – Timer 2 Mode Control Register
EXF2
Control and status bits for Timer 2 are contained in registers T2CON (see
T2MOD (see
16-bit timer register for Timer 2. The register pair {RCAP2H, RCAP2L} at addresses 0CBH and
0CAH are the 16-bit Capture/Reload register for Timer 2 in capture and auto-reload modes.
6
–
6
RCLK
5
Table
–
5
12-4). The register pair {TH2, TL2} at addresses 0CDH and 0CCH are the
TCLK
4
–
4
EXEN2
–
3
3
TR2
–
2
2
Reset Value = 0000 0000B
Reset Value = 0000 0000B
T2OE
C/T2
1
1
DCEN
CP/RL2
Table
3709D–MICRO–12/11
0
0
12-3) and