80C31X2 Datasheet, PDF (15/62 Pages) NXP Semiconductors – 80C51 8-bit microcontroller family 4K/8K/16K/32K ROM/OTP 128B/256B RAM low voltage 2.7 to 5.5 V, low power, high speed 30/33 MHz

Philips Semiconductors
80C51 8-bit microcontroller family
4K/8K/16K/32K ROM/OTP, low voltage (2.7 to 5.5 V),
low power, high speed (30/33 MHz)
Product data
P80C3xX2; P80C5xX2;
P87C5xX2
TMOD
Address = 89H
Not Bit Addressable
Reset Value = 00H
7
6
5
4
3
2
1
0
GATE C/T M1 M0 GATE C/T
M1
M0
TIMER 1
TIMER 0
BIT
TMOD.3/
TMOD.7
TMOD.2/
TMOD.6
SYMBOL
GATE
C/T
M1 M0
00
01
10
11
11
FUNCTION
Gating control when set. Timer/Counter “n” is enabled only while “INTn” pin is high and
“TRn” control pin is set. when cleared Timer “n” is enabled whenever “TRn” control bit is set.
Timer or Counter Selector cleared for Timer operation (input from internal system clock.)
Set for Counter operation (input from “Tn” input pin).
OPERATING
8048 Timer: “TLn” serves as 5-bit prescaler.
16-bit Timer/Counter: “THn” and “TLn” are cascaded; there is no prescaler.
8-bit auto-reload Timer/Counter: “THn” holds a value which is to be reloaded
into “TLn” each time it overflows.
(Timer 0) TL0 is an 8-bit Timer/Counter controlled by the standard Timer 0 control bits.
TH0 is an 8-bit timer only controlled by Timer 1 control bits.
(Timer 1) Timer/Counter 1 stopped.
SU01580
Figure 1. Timer/Counter 0/1 Mode Control (TMOD) Register
OSC
÷ d*
Tn Pin
C/T = 0
C/T = 1
Control
TLn
(5 Bits)
THn
(8 Bits)
TRn
Timer n
Gate bit
INTn Pin
*d = 6 in 6-clock mode; d = 12 in 12-clock mode.
Figure 2. Timer/Counter 0/1 Mode 0: 13-Bit Timer/Counter
TFn
Interrupt
SU01618
2003 Jan 24
15