AT89LP51 Atmel Corporation, AT89LP51 Datasheet - Page 50

• 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

Figure 11-5. Timer 0/1 Toggle Mode 2 Waveform
Table 11-4.
50
TMOD Address = 089H
Not Bit Addressable
Symbol
GATE1
C/T1
T1M1
T1M0
GATE0
C/T0
T0M1
T0M0
Bit
AT89LP51/52
GATE1
Function
Timer 1 Gating Control. When set, Timer/Counter 1 is enabled only while INT1 pin is high and TR1 control pin is set.
When cleared, Timer 1 is enabled whenever TR1 control bit is set.
Timer or Counter Selector 1. Cleared for Timer operation (input from internal system clock). Set for Counter operation
(input from T1 input pin). C/T1 must be zero when using Timer 1 in Clock Out mode.
Timer 1 Operating Mode
Mode
0
1
2
3
Timer 0 Gating Control. When set, Timer/Counter 0 is enabled only while INT0 pin is high and TR0 control pin is set.
When cleared, Timer 0 is enabled whenever TR0 control bit is set.
Timer or Counter Selector 0. Cleared for Timer operation (input from internal system clock). Set for Counter operation
(input from T0 input pin). C/T0 must be zero when using Timer 0 in Clock Out mode.
Timer 0 Operating Mode
Mode
0
1
2
3
7
TMOD – Timer/Counter Mode Control Register
T1M1
0
0
1
1
T0M1
0
0
1
1
C/T1
THx
FFh
6
Tx
T1M0
0
1
0
1
T0M0
0
1
0
1
T1M1
5
Operation
13-bit Timer Mode. 8-bit Timer/Counter TH1 with TL1 as 5-bit prescaler.
16-bit Timer Mode. TH1 and TL1 are cascaded to form a 16-bit Timer/Counter.
8-bit Auto Reload Mode. TH1 holds a value which is reloaded into 8-bit Timer/Counter
TL1 each time it overflows.
Timer/Counter 1 is stopped
Operation
13-bit Timer Mode. 8-bit Timer/Counter TH0 with TL0 as 5-bit prescaler.
16-bit Timer Mode. TH0 and TL0 are cascaded to form a 16-bit Timer/Counter.
8-bit Auto Reload Mode. TH0 holds a value which is reloaded into 8-bit Timer/Counter
TL0 each time it overflows.
Split Timer Mode. TL0 is an 8-bit Timer/Counter controlled by the standard Timer 0
control bits. TH0 is an 8-bit timer only controlled by Timer 1 control bits.
T1M0
4
GATE0
3
C/T0
2
Reset Value = 0000 0000B
T0M0
1
T0M1
3709D–MICRO–12/11
0