AT89LP51 Atmel Corporation, AT89LP51 Datasheet - Page 49

• 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

.
Table 11-2.
Table 11-3.
11.5
3709D–MICRO–12/11
Symbol
TF1
TR1
TF0
TR0
IE1
IT1
IE0
IT0
Symbol
T1OE
T0OE
SPEN
TCON = 88H
Bit Addressable
Bit
TCONB = 91H
Not Bit Addressable
Bit
Clock Output (Pin Toggle Mode)
Function
Timer 1 overflow flag. Set by hardware on Timer/Counter overflow. Cleared by hardware when the processor vectors
to interrupt routine.
Timer 1 run control bit. Set/cleared by software to turn Timer/Counter on/off.
Timer 0 overflow flag. Set by hardware on Timer/Counter overflow. Cleared by hardware when the processor vectors
to interrupt routine.
Timer 0 run control bit. Set/cleared by software to turn Timer/Counter on/off.
Interrupt 1 edge flag. Set by hardware when external interrupt edge detected. Cleared when interrupt processed.
Interrupt 1 type control bit. Set/cleared by software to specify falling edge/low level triggered external interrupts.
Interrupt 0 edge flag. Set by hardware when external interrupt edge detected. Cleared when interrupt processed.
Interrupt 0 type control bit. Set/cleared by software to specify falling edge/low level triggered external interrupts.
Function
Timer 1 Output Enable. Configures Timer 1 to toggle T1 (P3.5) upon overflow.
Timer 0 Output Enable. Configures Timer 0 to toggle T0 (P3.4) upon overflow.
Enables SPI mode for UART mode 0
TCON
TCONB
T1OE
TF1
7
7
– Timer/Counter Control Register
– Timer/Counter Control Register B
On the AT89LP51/52, Timer 0 and Timer 1 may be independently configured to toggle their
respective counter pins, T0 and T1, on overflow by setting the T0OE or T1OE bits in TCONB.
The C/Tx bits must be set to “0” when in toggle mode and the T0 (P3.4) and T1 (P3.5) pins must
be configured in an output mode. The Timer Overflow Flags and Interrupts will continue to func-
tion while in toggle mode and Timer 1 may still generate the baud rate for the UART. The timer
GATE function also works in toggle mode, allowing the output to be halted by an external input.
Toggle mode can be used with Timer Mode 2 to output a 50% duty cycle clock with 8-bit pro-
grammable frequency. Tx is toggled at every Timer x overflow with the pulse width determined
by the value of THx. An example waveform is given in
the output frequency for Timer 0 in Mode 2.
T0OE
TR1
6
6
SPEN
TF0
Mode 2:
5
5
TR0
4
–
4
f
out
=
System Frequency
------------------------------------------------- -
2
×
IE1
(
3
–
3
256 TH0
–
)
Figure
IT1
2
–
2
×
-------------------- -
TPS
11-5. The following formula gives
1
Reset Value = 0000 0000B
Reset Value = 0000 0000B
+
1
IE0
1
–
1
AT89LP51/52
IT0
0
–
0
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