Datasheet

Philips Semiconductors Product data
P80C3xX2; P80C5xX2;
P87C5xX2
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)
2003 Jan 24
22
Table 5. Timer 2 Generated Commonly Used
Baud Rates
Baud Rate Timer 2
12-clk
mode
6-clk
mode
Osc Freq
RCAP2H RCAP2L
375 K 750 K 12 MHz FF FF
9.6 K 19.2 K 12 MHz FF D9
4.8 K 9.6 K 12 MHz FF B2
2.4 K 4.8 K 12 MHz FF 64
1.2 K 2.4 K 12 MHz FE C8
300 600 12 MHz FB 1E
110 220 12 MHz F2 AF
300 600 6 MHz FD 8F
110 220 6 MHz F9 57
Summary Of Baud Rate Equations
Timer 2 is in baud rate generating mode. If Timer 2 is being clocked
through pin T2(P1.0) the baud rate is:
Baud Rate +
Timer 2 Overflow Rate
16
If Timer 2 is being clocked internally, the baud rate is:
Baud Rate +
f
OSC
[n [65536 * (RCAP2H, RCAP2L)]]
Where:
n = 16 in 6-clock mode, 32 in 12-clock mode.
f
OSC
= Oscillator Frequency
To obtain the reload value for RCAP2H and RCAP2L, the above
equation can be rewritten as:
RCAP2H, RCAP2L + 65536 *
ǒ
f
OSC
n Baud Rate
Ǔ
Timer/Counter 2 Set-up
Except for the baud rate generator mode, the values given for
T2CON do not include the setting of the TR2 bit. Therefore, bit TR2
must be set, separately, to turn the timer on. See Table 6 for set-up
of Timer 2 as a timer. Also see Table 7 for set-up of Timer 2 as a
counter.
Table 6. Timer 2 as a Timer
T2CON
MODE
INTERNAL
CONTROL
(Note 1)
EXTERNAL
CONTROL
(Note 2)
16-bit Auto-Reload 00H 08H
16-bit Capture 01H 09H
Baud rate generator receive
and transmit same baud rate
34H 36H
Receive only 24H 26H
Transmit only 14H 16H
Table 7. Timer 2 as a Counter
TMOD
MODE
INTERNAL
CONTROL
(Note 1)
EXTERNAL
CONTROL
(Note 2)
16-bit 02H 0AH
Auto-Reload 03H 0BH
NOTES:
1. Capture/reload occurs only on timer/counter overflow.
2. Capture/reload occurs on timer/counter overflow and a 1-to-0
transition on T2EX (P1.1) pin except when Timer 2 is used in the
baud rate generator mode.