80C51 Datasheet, PDF (11/38 Pages) NXP Semiconductors – 80C51 8-bit microcontroller family 4K/128 OTP/ROM/ROMless low voltage 2.7V.5.5V, low power, high speed 33 MHz

Philips Semiconductors
80C51 8-bit microcontroller family
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
Product specification
80C51/87C51/80C31
T2MOD Address = 0C9H
Reset Value = XXXX XX00B
Not Bit Addressable
—
—
—
—
—
—
T2OE DCEN
Bit
7
6
5
4
3
2
1
0
Symbol Function
—
T2OE
DCEN
Not implemented, reserved for future use.*
Timer 2 Output Enable bit.
Down Count Enable bit. When set, this allows Timer 2 to be configured as an up/down counter.
* User software should not write 1s to reserved bits. These bits may be used in future 8051 family products to invoke new features.
In that case, the reset or inactive value of the new bit will be 0, and its active value will be 1. The value read from a reserved bit is
indeterminate.
SU00729
Figure 3. Timer 2 Mode (T2MOD) Control Register
OSC
÷ 12
T2 PIN
C/T2 = 0
C/T2 = 1
TRANSITION
DETECTOR
CONTROL
TR2 _RELOAD
TL2
(8-BITS)
TH2
(8-BITS)
RCAP2L
RCAP2H
TF2
T2EX PIN
CONTROL
EXEN2
Figure 4. Timer 2 in Auto-Reload Mode (DCEN = 0)
EXF2
TIMER 2
INTERRUPT
SU00067
2000 Jan 20
11