P89C54X2BA NXP Semiconductors, P89C54X2BA Datasheet - Page 16

• Manufacturer Part Number: P89C54X2BA
• Manufacturer: NXP Semiconductors

Specifications of P89C54X2BA

• Cpu Family: 89C
• Device Core: 80C51
• Device Core Size: 8b
• Frequency (max): 20MHz
• Interface Type: UART
• Program Memory Type: Flash
• Program Memory Size: 16KB
• Total Internal Ram Size: 256Byte
• # I/os (max): 32
• Number Of Timers - General Purpose: 3
• Operating Supply Voltage (typ): 5V
• Operating Supply Voltage (max): 5.5V
• Operating Supply Voltage (min): 4.5V
• Instruction Set Architecture: CISC
• Operating Temp Range: 0C to 70C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Pin Count: 44
• Package Type: PLCC
• Lead Free Status / Rohs Status: Compliant

Philips Semiconductors
Table 4. Timer 2 Operating Modes
2002 Jun 06
80C51 8-bit Flash microcontroller family
4K/8K/16K/32K Flash
T2CON
RCLK + TCLK
Symbol
TF2
EXF2
RCLK
TCLK
EXEN2
TR2
C/T2
CP/RL2
X
0
0
1
Bit Addressable
Address = C8H
Position
T2CON.7
T2CON.6
T2CON.5
T2CON.4
T2CON.3
T2CON.2
T2CON.1
T2CON.0
TF2
7
Name and Significance
Timer 2 overflow flag set by a Timer 2 overflow and must be cleared by software. TF2 will not be set
when either RCLK or TCLK = 1.
Timer 2 external flag set when either a capture or reload is caused by a negative transition on T2EX and
EXEN2 = 1. When Timer 2 interrupt is enabled, EXF2 = 1 will cause the CPU to vector to the Timer 2
interrupt routine. EXF2 must be cleared by software. EXF2 does not cause an interrupt in up/down
counter mode (DCEN = 1).
Receive clock flag. When set, causes the serial port to use Timer 2 overflow pulses for its receive clock
in modes 1 and 3. RCLK = 0 causes Timer 1 overflow to be used for the receive clock.
Transmit clock flag. When set, causes the serial port to use Timer 2 overflow pulses for its transmit clock
in modes 1 and 3. TCLK = 0 causes Timer 1 overflows to be used for the transmit clock.
Timer 2 external enable flag. When set, allows a capture or reload to occur as a result of a negative
transition on T2EX if Timer 2 is not being used to clock the serial port. EXEN2 = 0 causes Timer 2 to
ignore events at T2EX.
Start/stop control for Timer 2. A logic 1 starts the timer.
Timer or counter select. (Timer 2)
Capture/Reload flag. When set, captures will occur on negative transitions at T2EX if EXEN2 = 1. When
cleared, auto-reloads will occur either with Timer 2 overflows or negative transitions at T2EX when
EXEN2 = 1. When either RCLK = 1 or TCLK = 1, this bit is ignored and the timer is forced to auto-reload
on Timer 2 overflow.
CP/RL2
X
X
0
1
EXF2
6
0 = Internal timer (OSC/12 in 12-clock mode or OSC/6 in 6-clock mode)
1 = External event counter (falling edge triggered).
Figure 6. Timer/Counter 2 (T2CON) Control Register
RCLK
5
TCLK
TR2
4
1
1
1
0
16
EXEN2
3
16-bit Auto-reload
16-bit Capture
Baud rate generator
(off)
TR2
2
P89C51X2/52X2/54X2/58X2
C/T2
1
Reset Value = 00H
MODE
CP/RL2
0
Preliminary data
SU01621