T89C51RD2-SLSIM Atmel, T89C51RD2-SLSIM Datasheet - Page 19

• Manufacturer Part Number: T89C51RD2-SLSIM
• Description: IC MICRO CTRL 64K FLASH 44PLCC
• Manufacturer: Atmel
• Series: 89Cr

Specifications of T89C51RD2-SLSIM

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 40MHz
• Connectivity: SPI, UART/USART
• Peripherals: POR, PWM, WDT
• Number Of I /o: 32
• Program Memory Size: 64KB (64K x 8)
• Program Memory Type: FLASH
• Eeprom Size: 2K x 8
• Ram Size: 1.25K x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 44-PLCC
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Data Converters: -

Figure 5. Auto-Reload Mode Up/Down Counter (DCEN = 1)
Programmable Clock-Output
4243G–8051–05/03
XTAL1
F
XTAL
In the clock-out mode, timer 2 operates as a 50%-duty-cycle, programmable clock gen-
erator (See Figure 6) . The input clock increments TL2 at frequency F
repeatedly counts to overflow from a loaded value. At overflow, the contents of RCAP2H
and RCAP2L registers are loaded into TH2 and TL2. In this mode, timer 2 overflows do
not generate interrupts. The formula gives the clock-out frequency as a function of the
system oscillator frequency and the value in the RCAP2H and RCAP2L registers :
For a 16 MHz system clock, timer 2 has a programmable frequency range of 61 Hz
(F
Timer 2 is programmed for the clock-out mode as follows:
•
•
•
•
•
It is possible to use timer 2 as a baud rate generator and a clock generator simulta-
neously. For this configuration, the baud rates and clock frequencies are not
independent since both functions use the values in the RCAP2H and RCAP2L registers.
OSC
Set T2OE bit in T2MOD register.
Clear C/T2 bit in T2CON register.
Determine the 16-bit reload value from the formula and enter it in RCAP2H/RCAP2L
registers.
Enter a 16-bit initial value in timer registers TH2/TL2. It can be the same as the
reload value or a different one depending on the application.
To start the timer, set TR2 run control bit in T2CON register.
/2
16)
Clock OutFrequency
to 4 MHz (F
F
OSC
–
OSC
(UP COUNTING RELOAD VALUE)
(DOWN COUNTING RELOAD
/4). The generated clock signal is brought out to T2 pin (P1.0).
T2
:12
RCAP2L
(8-bit)
(8-bit)
(8-bit)
TL2
FFh
=
T2CONreg
------------------------------------------------------------------------------------------- -
4
RCAP2H
C/T2
(8-bit)
(8-bit)
TH2
(8-bit)
0
FFh
1
×
(
65536 RCAP2H
T2CONreg
–
TR2
F
osc
T2EX:
if DCEN=1, 1=UP
if DCEN=1, 0=DOWN
if DCEN = 0, up
T2CONreg
TOGGL
TF2
⁄
RCAP2L
T89C51RD2
T2CONreg
EXF2
INTERRUPT
TIMER 2
OSC
)
/2. The timer
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