P87LPC760BDH NXP Semiconductors, P87LPC760BDH Datasheet - Page 19

• Manufacturer Part Number: P87LPC760BDH
• Description: MCU 8-Bit 87LP 80C51 CISC 1KB EPROM 5V 14-Pin TSSOP Tube
• Manufacturer: NXP Semiconductors

Specifications of P87LPC760BDH

• Package: 14TSSOP
• Device Core: 80C51
• Family Name: 87LP
• Maximum Speed: 20 MHz
• Ram Size: 128 Byte
• Program Memory Size: 1 KB
• Operating Supply Voltage: 5 V
• Data Bus Width: 8 Bit
• Program Memory Type: EPROM
• Number Of Programmable I/os: 12
• Interface Type: I2C/UART
• Operating Temperature: 0 to 70 °C
• Number Of Timers: 2

Philips Semiconductors
External Interrupt Inputs
The P87LPC760 has one individual interrupt input as well as the
Keyboard Interrupt function. The latter is described separately in this
section. The interrupt input are identical to those present on the
standard 80C51 microcontroller.
The external source can be programmed to be level-activated or
transition-activated by setting or clearing bit IT0 in Register TCON. If
IT0 = 0, external interrupt 0 is triggered by a detected low at the
INT0 pin. If IT0 = 1, external interrupt 0 is edge triggered. In this
mode if successive samples of the INT0 pin show a high in one
cycle and a low in the next cycle, interrupt request flag IE0 in TCON
is set, causing an interrupt request.
Since the external interrupt pin is sampled once each machine
cycle, an input high or low should hold for at least 6 CPU Clocks to
ensure proper sampling. If the external interrupt is
2002 Mar 07
Low power, low price, low pin count (14 pin)
microcontroller with 1 kbyte OTP
EWD
WDT
EBO
CM1
BOF
EKB
EX0
KBF
EC1
IE0
Figure 9. Interrupt Sources, Interrupt Enables, and Power Down Wakeup Sources
RI + TI
ATN
TF0
ET0
TF1
ET1
EI2
ES
16
transition-activated, the external source has to hold the request pin
high for at least one machine cycle, and then hold it low for at least
one machine cycle. This is to ensure that the transition is detected
and that interrupt request flag IE0 is set. IE0 is automatically cleared
by the CPU when the service routine is called.
If the external interrupt is level-activated, the external source must
hold the request active until the requested interrupt is actually
generated. If the external interrupt is still asserted when the interrupt
service routine is completed another interrupt will be generated. It is
not necessary to clear the interrupt flag IE0 when the interrupt is
level sensitive, it simply tracks the input pin level.
If the external interrupt is enabled when the P87LPC760 is put into
Power Down or Idle mode, the interrupt will cause the processor to
wake up and resume operation. Refer to the section on Power
Reduction Modes for details.
(FROM IEN0
REGISTER)
EA
P87LPC760
INTERRUPT
(IF IN POWER
TO CPU
WAKEUP
SU01534
DOWN)
Preliminary data