P89LV51RD2BBC NXP Semiconductors, P89LV51RD2BBC Datasheet - Page 35

• Manufacturer Part Number: P89LV51RD2BBC
• Description: MCU 8-Bit 89LV 80C51 CISC 64KB Flash 3.3V 44-Pin TQFP Tray
• Manufacturer: NXP Semiconductors

Specifications of P89LV51RD2BBC

• Package: 44TQFP
• Device Core: 80C51
• Family Name: 89LV
• Maximum Speed: 40 MHz
• Ram Size: 1 KB
• Program Memory Size: 64 KB
• Operating Supply Voltage: 3.3 V
• Data Bus Width: 8 Bit
• Program Memory Type: Flash
• Number Of Programmable I/os: 32
• Interface Type: SPI/UART
• Operating Temperature: 0 to 70 °C
• Number Of Timers: 3

NXP Semiconductors
P89LV51RB2_RC2_RD2_5
Product data sheet
Fig 13. Timer 2 in Auto Reload mode (DCEN = 1)
OSC
T2 pin
6.5.3 Programmable clock-out
6.5.4 Baud rate generator mode
6
A logic 0 applied at pin T2EX causes Timer 2 to count down. The timer will underflow
when TL2 and TH2 become equal to the value stored in RCAP2L and RCAP2H. Timer 2
underflow sets the TF2 flag and causes 0FFFFH to be reloaded into the timer registers
TL2 and TH2. The external flag EXF2 toggles when Timer 2 underflows or overflows. This
EXF2 bit can be used as a 17th bit of resolution if needed.
A 50 % duty cycle clock can be programmed to come out on pin T2 (P1.0). This pin,
besides being a I/O pin, has two additional functions. It can be programmed:
To configure the Timer/counter 2 as a clock generator, bit C/T2 (in T2CON) must be
cleared and bit T2OE in T2MOD must be set. Bit TR2 (T2CON.2) also must be set to start
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 Equation 2:
Where (RCAP2H, RCAP2L) = the content of RCAP2H and RCAP2L taken as a 16-bit
unsigned integer.
In the Clock-Out mode, Timer 2 roll-overs will not generate an interrupt. This is similar to
when it is used as a baud-rate generator.
Bits TCLK and/or RCLK in T2CON allow the UART transmit and receive baud rates to be
derived from either Timer 1 or Timer 2 (See
When TCLK = 0, Timer 1 is used as the UART transmit baud rate generator. When
------------------------------------------------------------------------------------ -
2
•
•
To input the external clock for Timer/counter 2, or
To output a 50 % duty cycle clock ranging from 122 Hz to 8 MHz at a 16 MHz
operating frequency.
65536
Oscillator Frequency
C/T2 = 0
C/T2 = 1
RCAP2H, RCAP2L
Rev. 05 — 15 December 2009
TR2
control
(down-counting reload value)
(up-counting reload value)
RCAP2L RCAP2H
(8-bits)
FFH
TL2
P89LV51RB2/RC2/RD2
(8-bits)
FFH
TH2
Section 6.6 “UART” on page 37
8-bit microcontrollers with 80C51 core
underflow
overflow
T2EX pin
count direction
1 = up
0 = down
toggle
TF2
© NXP B.V. 2009. All rights reserved.
002aaa525
EXF2
timer 2
interrupt
for details).
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