NXP Semiconductors P89LPC9321 UM10310 - Manual (Page 62)

UM10310 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.
User manual Rev. 2 — 1 November 2010 62 of 139
NXP Semiconductors
UM10310
P89LPC9321 User manual
Table 55. Serial Port Control register (SCON - address 98h) bit allocation
Bit 7 6 5 4 3 2 1 0
Symbol SM0/FE SM1 SM2 REN TB8 RB8 TI RI
Reset x x x x x x 0 0
Table 56. Serial Port Control register (SCON - address 98h) bit description
Bit Symbol Description
0 RI Receive interrupt flag. Set by hardware at the end of the 8th bit time in Mode 0, or
approximately halfway through the stop bit time in Mode 1. For Mode 2 or Mode 3,
if SMOD0, it is set near the middle of the 9th data bit (bit 8). If SMOD0 = 1, it is set
near the middle of the stop bit (see SM2 - SCON.5 - for exceptions). Must be
cleared by software.
1 TI Transmit interrupt flag. Set by hardware at the end of the 8th bit time in Mode 0, or
at the stop bit (see description of INTLO bit in SSTAT register) in the other modes.
Must be cleared by software.
2 RB8 The 9th data bit that was received in Modes 2 and 3. In Mode 1 (SM2 must be 0),
RB8 is the stop bit that was received. In Mode 0, RB8 is undefined.
3 TB8 The 9th data bit that will be transmitted in Modes 2 and 3. Set or clear by software
as desired.
4 REN Enables serial reception. Set by software to enable reception. Clear by software to
disable reception.
5 SM2 Enables the multiprocessor communication feature in Modes 2 and 3. In Mode 2 or
3, if SM2 is set to 1, then Rl will not be activated if the received 9th data bit (RB8)
is 0. In Mode 0, SM2 should be 0. In Mode 1, SM2 must be 0.
6 SM1 With SM0 defines the serial port mode, see Table 57 .
7 SM0/FE The use of this bit is determined by SMOD0 in the PCON register. If SMOD0 = 0,
this bit is read and written as SM0, which with SM1, defines the serial port mode. If
SMOD0 = 1, this bit is read and written as FE (Framing Error). FE is set by the
receiver when an invalid stop bit is detected. Once set, this bit cannot be cleared
by valid frames but is cleared by software. (Note: UART mode bits SM0 and SM1
should be programmed when SMOD0 is logic 0 - default mode on any reset.)
Table 57. Serial Port modes
SM0, SM1 UART mode UART baud rate
00 Mode 0: shift register CCLK ⁄
16
(default mode on any reset)
01 Mode 1: 8-bit UART Variable (see Table 52 )
10 Mode 2: 9-bit UART CCLK ⁄
32
or CCLK ⁄
16
11 Mode 3: 9-bit UART Variable (see Table 52 )
Table 58. Serial Port Status register (SSTAT - address BAh) bit allocation
Bit 7 6 5 4 3 2 1 0
Symbol DBMOD INTLO CIDIS DBISEL FE BR OE STINT
Reset x x x x x x 0 0