Philips P89LPC906 SFR Space, Baud Rate Generator and Selection, Updating the BRGR1 and BRGR0 Sfrs

Models: P89LPC907 P89LPC908 P89LPC906

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Philips Semiconductors

User’s Manual - Preliminary -

 

 

 

UART

P89LPC906/907/908

SFR SPACE

 

 

The UART SFRs are at the following locations:

Table 8-1: SFR Locations for UARTs

Register

Description

SFR Location

 

 

 

PCON

Power Control

87H

 

 

 

SCON

Serial Port (UART) Control

98H

 

 

 

SBUF

Serial Port (UART) Data Buffer

99H

 

 

 

SADDR

Serial Port (UART) Address

A9H

 

 

 

SADEN

Serial Port (UART) Address Enable

B9H

 

 

 

SSTAT

Serial Port (UART) Status

BAH

 

 

 

BRGR1

Baud Rate Generator Rate High Byte

BFH

 

 

 

BRGR0

Baud Rate Generator Rate Low Byte

BEH

 

 

 

BRGCON

Baud Rate Generator Control

BDH

 

 

 

BAUD RATE GENERATOR AND SELECTION

The enhanced UART has an independent Baud Rate Generator. The baud rate is determined by a value programmed into the BRGR1 and BRGR0 SFRs. The UART can use either Timer 1 or the baud rate generator output as determined by BRGCON.2- 1 (see Figure 8-2). Note that Timer T1 is further divided by 2 if the SMOD1 bit (PCON.7) is cleared. The independent Baud Rate Generator uses CCLK.

UPDATING THE BRGR1 AND BRGR0 SFRS

The baud rate SFRs, BRGR1 and BRGR0 must only be loaded when the Baud Rate Generator is disabled (the BRGEN bit in the BRGCON register is ’0’). This avoids the loading of an interim value to the baud rate generator. (CAUTION: If either BRGR0 or BRGR1 is written when BRGEN = 1, the result is unpredictable.)

Table 8-2: Baud Rate Generation for UART

SCON.7

SCON.6

PCON.7

BRGCON.1

Receive/Transmit Baud Rate for UART

(SM0)

(SM1)

(SMOD1)

(SBRGS)

 

 

 

 

 

 

0

0

X

X

CCLK/16

 

 

 

 

 

 

 

0

0

CCLK/(256-TH1)64

 

 

 

 

 

0

1

1

0

CCLK/(256-TH1)32

 

 

 

 

 

 

 

X

1

CCLK/((BRGR1,BRGR0)+16)

 

 

 

 

 

1

0

0

X

CCLK/32

 

 

 

1

X

CCLK/16

 

 

 

 

 

 

 

 

 

0

0

CCLK/(256-TH1)64

 

 

 

 

 

1

1

1

0

CCLK/(256-TH1)32

 

 

 

 

 

 

 

X

1

CCLK/((BRGR1,BRGR0)+16)

 

 

 

 

 

2003 Dec 8

60

Page 60
Image 60
Philips P89LPC906 SFR Space, Baud Rate Generator and Selection, Updating the BRGR1 and BRGR0 Sfrs, SFR Locations for UARTs