参数资料
型号: P89C54UFBB
厂商: NXP SEMICONDUCTORS
元件分类: 微控制器/微处理器
英文描述: 80C51 8-bit microcontroller family 4K/8K/16K/32K Flash
中文描述: 8-BIT, FLASH, 33 MHz, MICROCONTROLLER, PQFP44
封装: PLASTIC, QFP-44
文件页数: 13/32页
文件大小: 212K
代理商: P89C54UFBB
Philips Semiconductors
Product specification
89C51/89C52/89C54/89C58
80C51 8-bit microcontroller family
4K/8K/16K/32K Flash
1999 Oct 27
13
When Timer 2 is in the baud rate generator mode, one should not try
to read or write TH2 and TL2. As a baud rate generator, Timer 2 is
incremented every state time (osc/2) or asynchronously from pin T2;
under these conditions, a read or write of TH2 or TL2 may not be
accurate. The RCAP2 registers may be read, but should not be
written to, because a write might overlap a reload and cause write
and/or reload errors. The timer should be turned off (clear TR2)
before accessing the Timer 2 or RCAP2 registers.
Table 4 shows commonly used baud rates and how they can be
obtained from Timer 2.
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:
Timer 2 Overflow Rate
16
Baud Rate
If Timer 2 is being clocked internally , the baud rate is:
Baud Rate
f
OSC
(RCAP2H,RCAP2L)]]
[32
[65536
Where f
OSC
= Oscillator Frequency
To obtain the reload value for RCAP2H and RCAP2L, the above
equation can be rewritten as:
RCAP2H,RCAP2L
65536
f
OSC
Baud Rate
32
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 5 for set-up of Timer 2
as a timer. Also see Table 6 for set-up of Timer 2 as a counter.
Table 5.
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 6.
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.
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P89C54UFPN 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:80C51 8-bit microcontroller family 4K/8K/16K/32K Flash
P89C54X2 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:80C51 8-bit Flash microcontroller family
P89C54X2BA 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:80C51 8-bit Flash microcontroller family
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P89C54X2BBD 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:80C51 8-bit Flash microcontroller family