More About Uart Modes 2 And 3; Framing Error And Ri In Modes 2 And 3 With Sm2 = 1 - Philips P89LPC938 User Manual

Philips Semiconductors
TX clock
write to
SBUF
shift
TXD
TI
RX
clock
÷16 reset
RXD
shift
RI
Fig 28. Serial Port Mode 1 (only single transmit buffering case is shown).

11.12 More about UART Modes 2 and 3

Reception is the same as in Mode 1.
The signal to load SBUF and RB8, and to set RI, will be generated if, and only if, the
following conditions are met at the time the final shift pulse is generated. (a) RI = 0, and
(b) Either SM2 = 0, or the received 9th data bit = 1. If either of these conditions is not met,
the received frame is lost, and RI is not set. If both conditions are met, the received 9th
data bit goes into RB8, and the first 8 data bits go into SBUF.
TX clock
write to
SBUF
shift
TXD
TI
RX
clock
÷16 reset
RXD
shift
RI
Fig 29. Serial Port Mode 2 or 3 (only single transmit buffering case is shown).

11.13 Framing error and RI in Modes 2 and 3 with SM2 = 1

If SM2 = 1 in modes 2 and 3, RI and FE behaves as in the following table.
User manual
start
D0 D1 D2
bit
start
D0 D1 D2
bit
start
D0 D1 D2
bit
start
D0 D1 D2
bit
Rev. 03 — 7 June 2005
D3 D4 D5 D6
INTLO = 0
D3 D4 D5 D6
D3 D4 D5 D6
D3 D4 D5 D6
UM10119
P89LPC938 User manual
transmit
D7 stop bit
INTLO = 1
D7 stop bit
receive
002aaa926
transmit
D7 TB8 stop bit
INTLO = 0 INTLO = 1
D7 RB8
stop bit
receive
SMOD0 = 0 SMOD0 = 1
002aaa927
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
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