P87LPC764BD NXP Semiconductors, P87LPC764BD Datasheet - Page 31

• Manufacturer Part Number: P87LPC764BD
• Description: MCU 8-Bit 87LP 80C51 CISC 4KB EPROM 5V 20-Pin SO Tube
• Manufacturer: NXP Semiconductors

Specifications of P87LPC764BD

• Package: 20SO
• Device Core: 80C51
• Family Name: 87LP
• Maximum Speed: 20 MHz
• Ram Size: 128 Byte
• Program Memory Size: 4 KB
• Operating Supply Voltage: 5 V
• Data Bus Width: 8 Bit
• Program Memory Type: EPROM
• Number Of Programmable I/os: 18
• Interface Type: I2C/UART
• Operating Temperature: 0 to 70 °C
• Number Of Timers: 2

Philips Semiconductors
Mode 1
Mode 1 is the same as Mode 0, except that all 16 bits of the timer
register (THn and TLn) are used. See Figure 25
Mode 2
Mode 2 configures the Timer register as an 8-bit Counter (TL1) with
automatic reload, as shown in Figure 26. Overflow from TLn not only
sets TFn, but also reloads TLn with the contents of THn, which must
be preset by software. The reload leaves THn unchanged. Mode 2
operation is the same for Timer 0 and Timer 1.
Mode 3
When Timer 1 is in Mode 3 it is stopped. The effect is the same as
setting TR1 = 0.
2003 Sep 03
Low power, low price, low pin count (20 pin)
microcontroller with 4 kbyte OTP
OSC/6
OSC/6
OSC/12
OSC/12
INTn PIN
INTn PIN
Tn PIN
Tn PIN
GATE
GATE
TRn
TRn
OR
or
Figure 26. Timer/Counter 0 or 1 in Mode 2 (8-Bit Auto-Reload)
C/T = 1
C/T = 1
Figure 25. Timer/Counter 0 or 1 in Mode 1 (16-Bit Counter)
C/T = 0
C/T = 0
CONTROL
CONTROL
30
Timer 0 in Mode 3 establishes TL0 and TH0 as two separate 8-bit
counters. The logic for Mode 3 on Timer 0 is shown in Figure 27.
TL0 uses the Timer 0 control bits: C/T, GATE, TR0 and pin INT0,
and TF0. TH0 is locked into a timer function (counting machine
cycles) and takes over the use of TR1 and TF1 from Timer 1. Thus,
TH0 now controls the “Timer 1” interrupt.
Mode 3 is provided for applications that require an extra 8-bit timer.
With Timer 0 in Mode 3, an P87LPC764 can look like it has three
Timer/Counters. When Timer 0 is in Mode 3, Timer 1 can be turned
on and off by switching it into and out of its own Mode 3. It can still
be used by the serial port as a baud rate generator, or in any
application not requiring an interrupt.
(8 BITS)
(8 BITS)
(8 BITS)
THn
TLn
TLn
RELOAD
(8 BITS)
THn
OVERFLOW
TOGGLE
TOGGLE
OVERFLOW
TnOE
TnOE
TFn
TFn
P87LPC764
INTERRUPT
Tn PIN
INTERRUPT
Tn PIN
SU01174
SU01392
Product data