AT89LP3240 Atmel Corporation, AT89LP3240 Datasheet - Page 68

• Manufacturer Part Number: AT89LP3240
• Manufacturer: Atmel Corporation

Specifications of AT89LP3240

• Flash (kbytes): 32 Kbytes
• Max. Operating Frequency: 20 MHz
• Cpu: 8051-1C
• Max I/o Pins: 38
• Spi: 1
• Twi (i2c): 1
• Uart: 1
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 153.8
• Sram (kbytes): 4.25
• Eeprom (bytes): 8192
• Self Program Memory: IAP
• Operating Voltage (vcc): 2.4 to 3.6
• Timers: 3
• Isp: SPI/OCD
• Watchdog: Yes

Figure 12-8. Timer 2 in Baud Rate Generator Mode
12.5
68
Frequency Generator (Programmable Clock Out)
AT89LP3240/6440
T2EX PIN
OSC
T2 PIN
erator, T2EX can be used as an extra external interrupt. Also note that the Baud Rate and
Frequency Generator modes may be used simultaneously.
Timer 2 can generate a 50% duty cycle clock on T2 (P1.0), as shown in
besides being a regular I/O pin, has two alternate functions. It can be programmed to input the
external clock for Timer/Counter 2 or to toggle its output at every timer overflow. To configure
the Timer/Counter 2 as a clock generator, bit C/T2 (T2CON.1) must be cleared and bit T2OE
(T2MOD.1) must be set. Bit TR2 (T2CON.2) starts and stops the timer.
The clock-out frequency depends on the oscillator frequency and the reload value of Timer 2
capture registers (RCAP2H, RCAP2L), as shown in the following equations.
In the frequency generator mode, Timer 2 roll-overs will not generate an interrupt. This behavior
is similar to when Timer 2 is used as a baud-rate generator. It is possible to use Timer 2 as a
baud-rate generator and a clock generator simultaneously. Note, however, that the baud-rate
and clock-out frequencies cannot be determined independently from one another since they
both use RCAP2H and RCAP2L.
÷TPS
TRANSITION
DETECTOR
T2CM = 00B
T2CM = 01B
C/T2 = 0
C/T2 = 1
EXEN2
TR2
Clock Out Frequency
Clock Out Frequency
RCAP2L
TL2
EXF2
RCAP2H
TH2
=
=
------------------------------------------------------------------------------------------- -
2
------------------------------------------------------------------------------ -
2
×
×
[
[
65536
Oscillator Frequency
(
INTERRUPT
RCAP2H,RCAP2L
TIMER 2
Oscillator Frequency
÷
2
"1"
"1"
–
TIMER 1 OVERFLOW
(
RCAP2H,RCAP2L
"0"
"0"
"0"
"1"
)
+
÷
SMOD1
RCLK
TCLK
÷
1
16
16
]
Figure
×
)
-------------------- -
TPS
]
CLOCK
CLOCK
×
Rx
Tx
1
-------------------- -
TPS
3706C–MICRO–2/11
+
12-9. This pin,
1
1
+
1