Datasheet

Philips Semiconductors Product data
P80C3xX2; P80C5xX2;
P87C5xX2
80C51 8-bit microcontroller family
4K/8K/16K/32K ROM/OTP, low voltage (2.7 to 5.5 V),
low power, high speed (30/33 MHz)
2003 Jan 24
29
80C51 Internal Bus
SBUF
Zero Detector
D Q
S
CL
Write
to
SBUF
TX Control
TX Clock Send
DataStart
RX Control
Start
RX Clock
T1
Serial
Port
Interrupt
Input Shift Register
(9 Bits)
Load
SBUF
Shift
SBUF
Read
SBUF
80C51 Internal Bus
TxD
TB8
÷ 16
1-to-0
Transition
Detector
Sample
÷ 2
Timer 1
Overflow
SMOD = 1
SMOD = 0
Shift
Bit Detector
RxD
R1
÷ 16
Load
SBUF
Shift
1FFH
Transmit
Send
S1P1
Shift
TX
Clock
Write to SBUF
Start Bit
TxD
Stop BitD0 D1 D2 D3 D4 D5 D6 D7
TI
RX
Clock
÷ 16 Reset
Start
Bit
RxD
Stop BitD0 D1 D2 D3 D4 D5 D6 D7
Bit Detector
Sample Times
Shift
RI
Receive
Data
TB8
RB8
Stop Bit Gen.
SU00542
Figure 17. Serial Port Mode 3