P89V52X2FN datasheet(25/56 Pages) PHILIPS

25 / 56 page

P89V52X2_1

Preliminary data sheet

Rev. 01 — 7 June 2007

25 of 56

NXP Semiconductors

P89V52X2

80C51 with 256 B RAM, 192 B data EEPROM

When Timer 2 is in the baud rate generator mode, one should not try to read or write TH2

and TL2. 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 20 shows commonly used baud

rates and how they can be obtained from Timer 2.

6.9.5 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 = fosc / (16 × (65536 − (RCAP2H, RCAP2L)))

Where fosc = oscillator frequency

To obtain the reload value for RCAP2H and RCAP2L, the above equation can be rewritten

as:

RCAP2H, RCAP2L = 65536

− f

osc / (16 × baud rate)

6.10 UART

The UART operates in all standard modes. Enhancements over the standard 80C51

UART include Framing Error detection, and automatic address recognition.

6.10.1 Mode 0

Serial data enters and exits through RXD and TXD outputs the shift clock. Only 8 bits are

transmitted or received, LSB first. The baud rate is fixed at 1

⁄

6 of the CPU clock frequency.

UART configured to operate in this mode outputs serial clock on TXD line no matter

whether it sends or receives data on RXD line.

Table 20.

Timer 2 generated commonly used baud rates

Rate

Oscillator frequency

Timer 2

RCAP2H

RCAP2L

750 kBd

12 MHz

19.2 kBd

12 MHz

9.6 kBd

12 MHz

4.8 kBd

12 MHz

2.4 kBd

12 MHz

600 Bd

12 MHz

220 Bd

12 MHz

600 Bd

6 MHz

220 Bd

6 MHz

P89V52X2FN Datasheet(PDF) 25 Page - NXP Semiconductors

P89V52X2FN Datasheet(HTML) 25 Page - NXP Semiconductors

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56

Datasheet Download

Link URL