MPC89L51A Megawin Technology, MPC89L51A Datasheet - Page 24

• Manufacturer Part Number: MPC89L51A
• Description: 8-bit micro-controller
• Manufacturer: Megawin Technology

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Mode2
An 11-bits data is serially transmitted through TXD or received through RXD. The frame data
includes a start bits (0), 8 data bits, a programmable 9
9
The baud rate is programmable, and permitted to be set either 1/32 or 1/64 the oscillator
frequency.
Mode3
Mode 3 is the same as mode 2 except the baud rate is variable.
In all four modes, transmission is initiated by any instruction that uses SBUF as a destination
register. Reception is initiated in mode 0 by the condition RI = 0 and REN = 1. Reception is
initiated in the other modes by the incoming start bits with 1-to-0 transition if REN=1.
There are several SFR related to serial port configuration described as following.
SFR: SCON (Serial Port Control):
{ SM0, SM1 }: Used to set operating mode of the serial port. It is enabled to access by clearing SMOD0.
FE: Frame Error bits. This bits is set by the receiver when an invalid stop bits is detected. The FE bits is not
24
th
SM0/FE
data bits comes from TB8 in SFR SCON. On receive, the 9
Bits-7
cleared by valid frames, but should be cleared by software. The SMOD0 (PCON.6) bits must be set to
enable access to the FE bits.
{ 0, 0 } := set the serial port operate under Mode 0
{ 0, 1 } := set the serial port operate under Mode 1
{ 1, 0 } := set the serial port operate under Mode 2
{ 1, 1 } := set the serial port operate under Mode 3
Bits-6
SM1
Baud Rate (for Mode 3)
Baud Rate (for Mode 2)
Bits-5
SM2
or =
MPC89x51A Data Sheet
=
Bits-4
REN
=
(Timer-2 overflow rate)
2
SMOD
32
Bits-3
2
TB8
16
64
SMOD
X
th
bits and a stop bits (1). On transmit, the
(Timer-1 overflow rate)
Bits-2
RB8
X F
th
data bits goes into RB8 in SCON.
osc
Bits-1
TI
Bits-0
RI
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