P87C552SBAA NXP Semiconductors, P87C552SBAA Datasheet - Page 17

• Manufacturer Part Number: P87C552SBAA
• Description: MCU 8-Bit 87C 80C51 CISC 8KB EPROM 3.3V/5V 68-Pin PLCC Tube
• Manufacturer: NXP Semiconductors

Specifications of P87C552SBAA

• Package: 68PLCC
• Device Core: 80C51
• Family Name: 87C
• Maximum Speed: 16 MHz
• Operating Supply Voltage: 3.3|5 V
• Data Bus Width: 8 Bit
• Number Of Programmable I/os: 40
• Interface Type: I2C/UART
• On-chip Adc: 8-chx10-bit
• Number Of Timers: 3
• Ram Size: 256 Byte
• Program Memory Size: 8 KB
• Program Memory Type: EPROM
• Operating Temperature: 0 to 70 °C

Philips Semiconductors
Capture Logic: The four 16-bit capture registers that Timer T2 is
connected to are: CT0, CT1, CT2, and CT3. These registers are
loaded with the contents of Timer T2, and an interrupt is requested
upon receipt of the input signals CT0I, CT1I, CT2I, or CT3I. These
input signals are shared with port 1. The four interrupt flags are in
the Timer T2 interrupt register (TM2IR special function register). If
the capture facility is not required, these inputs can be regarded as
additional external interrupt inputs.
Using the capture control register CTCON (see Figure 13), these
inputs may capture on a rising edge, a falling edge, or on either a
rising or falling edge. The inputs are sampled during S1P1 of each
cycle. When a selected edge is detected, the contents of Timer T2
are captured at the end of the cycle.
Measuring Time Intervals Using Capture Registers: When a
recurring external event is represented in the form of rising or falling
edges on one of the four capture pins, the time between two events
2003 Apr 01
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I
capture/compare, high I/O, low voltage (2.7 V to 5.5 V), low power
T2ER
f
RT2
osc
T2
off
STE
TG
TG
S
S
S
S
S
S
External reset
enable
1/12
RTE
R
R
R
R
R
R
T
T
CT0I
CT0
CTI0
INT
P4.0
P4.1
P4.2
P4.3
P4.4
P4.5
P4.6
P4.7
Prescaler
2
Figure 12. Block Diagram of Timer 2
C, PWM,
I/O port 4
CT1I
CT1
CTI1
INT
17
T2 Counter
S
R
T
TG =
can be measured using Timer T2 and a capture register. When an
event occurs, the contents of Timer T2 are copied into the relevant
capture register and an interrupt request is generated. The interrupt
service routine may then compute the interval time if it knows the
previous contents of Timer T2 when the last event occurred. With a
12MHz oscillator, Timer T2 can be programmed to overflow every
524ms. When event interval times are shorter than this, computing
the interval time is simple, and the interrupt service routine is short.
For longer interval times, the Timer T2 extension routine may be
used.
Compare Logic: Each time Timer T2 is incremented, the contents
of the three 16-bit compare registers CM0, CM1, and CM2 are
compared with the new counter value of Timer T2. When a match is
found, the corresponding interrupt flag in TM2IR is set at the end of
the following cycle. When a match with CM0 occurs, the controller
sets bits 0-5 of port 4 if the corresponding bits of the set enable
register STE are at logic 1.
=
=
=
set
reset
toggle
toggle status
CMO (S)
COMP
CT2I
8-bit overflow interrupt
16-bit overflow interrupt
CT2
T2 SFR address:
INT
CTI2
INT
CM1 (R)
COMP
TML2
TMH2
INT
=
=
CT3I
lower 8 bits
higher 8 bits
CT3
CM2 (T)
COMP
CTI3
INT
P87C552
Product data
SU00757
INT