© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
User manual
Rev. 03 — 7 June 2005
67 of 139
Philips Semiconductors
UM10119
P89LPC938 User manual
11.7 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 logic 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.)
11.8 Framing error
A Framing error occurs when the stop bit is sensed as a logic 0. A Framing error is
reported in the status register (SSTAT). In addition, if SMOD0 (PCON.6) is 1, framing
errors can be made available in SCON.7. If SMOD0 is 0, SCON.7 is SM0. It is
recommended that SM0 and SM1 (SCON[7:6]) are programmed when SMOD0 is logic 0.
Table 62:
UART baud rate generation
SCON.7
(SM0)
SCON.6
(SM1)
PCON.7
(SMOD1)
BRGCON.1
(SBRGS)
Receive/transmit baud rate for UART
0
0
X
X
CCLK
⁄
16
0
1
0
0
CCLK
⁄
(256
−
TH1)64
1
0
CCLK
⁄
(256
−
TH1)32
X
1
CCLK
⁄
((BRGR1, BRGR0)+16)
1
0
0
X
CCLK
⁄
32
1
X
CCLK
⁄
16
1
1
0
0
CCLK
⁄
(256
−
TH1)64
1
0
CCLK
⁄
(256
−
TH1)32
X
1
CCLK
⁄
((BRGR1, BRGR0)+16)
Table 63:
Baud Rate Generator Control register (BRGCON - address BDh) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
--
-
-
-
-
-
SBRGS
BRGEN
Reset
x
x
x
x
x
x
0
0
Table 64:
Baud Rate Generator Control register (BRGCON - address BDh) bit description
Bit Symbol
Description
0
BRGEN
Baud Rate Generator Enable. Enables the baud rate generator. BRGR1 and
BRGR0 can only be written when BRGEN = 0.
1
SBRGS
Select Baud Rate Generator as the source for baud rates to UART in modes 1 and
3 (see
for details)
2:7 -
reserved
Fig 26. Baud rate generation for UART (Modes 1, 3).
baud rate modes 1 and 3
SBRGS = 1
SBRGS = 0
SMOD1 = 0
SMOD1 = 1
timer 1 overflow
(PCLK-based)
baud rate generator
(CCLK-based)
002aaa897
÷
2