W78E516DDG Datasheet, PDF (63/90 Pages) Nuvotem Talema – 8-BIT MICROCONTROLLER

W78E516D/W78E058D Data Sheet
2. Either SM2 = 0, or the received stop bit = 1.
If these conditions are met, then the stop bit goes to RB8, the 8 data bits go into SBUF and RI is set.
Otherwise the received frame may be lost. After the middle of the stop bit, the receiver goes back to
looking for a 1-to-0 transition on the RxD pin.
MODE 3
This mode is similar to Mode 2 in all respects, except that the baud rate is programmable. The user
must first initialize the Serial related SFR SCON before any communication can take place. This in-
volves selection of the Mode and baud rate. The Timer 1 should also be initialized if modes 1 and 3
are used. In all four modes, transmission is started by any instruction that uses SBUF as a destination
register. Reception is initiated in Mode 0 by the condition RI = 0 and REN = 1. This will generate a
clock on the TxD pin and shift in 8 bits on the RxD pin. Reception is initiated in the other modes by the
incoming start bit if REN = 1. The external device will start the communication by transmitting the start
bit.
Timer 1
Overflow
Timer 2
Overflow
1/2
SMOD 0 1
0
1
TCLK
RCLK ⁰
1
1/16
1/16
SAMPLE
1-To-0
DETECTOR
RXD
Write to
SBUF
TX START
TX CLOCK
1
TB8
Internal
Data Bus
0
TX SHIFT
Transmit Shift Register
STOP
D8
PARIN
START ^SOUT
TXD
LOAD
CLOCK
Serial
Controllor ^TI
RX CLOCK
RI
TX START
LOAD SBUF
RX SHIFT
Serial Interrupt
Read SBUF
BIT
DETECTOR
CLOCK PAROUT
SIN
D8
Receive Shift Register
SBUF
RB8
Internal
Data Bus
Figure 15- 4 Serial port mode 3
SM0 SM1 Mode
0
0
0
0
1
1
Type
Synch.
Asynch.
Baud Clock
4 or 12 TCLKS
Timer 1 or 2
Frame
Size
8 bits
10 bits
Start
Bit
No
1
Stop
Bit
No
1
9th bit
Function
None
None
- 63 -
Publication Release Date: Feb 15, 2011
Revision A09