UPSD3254 STMICROELECTRONICS [STMicroelectronics], UPSD3254 Datasheet - Page 66

• Manufacturer Part Number: UPSD3254
• Description: Flash Programmable System Devices with 8032 Microcontroller Core
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

UPSD3254A, UPSD3254BV, UPSD3253B, UPSD3253BV
ditions are met at the time the final shift pulse is
generated:
1. RI = 0, and
2. Either SM2 = 0, or the received 9th data bit = 1
If either of these conditions is not met, the received
frame is irretrievably lost, and RI is not set. If both
Figure 27. Serial Port Mode 0, Block Diagram
66/175
SBUF
Write
to
REN
R1
S6
Interrupt
Serial
Port
D
CL
S
Rx Clock
Tx Clock
Start
Start
SBUF
Q
Read
SBUF
Load
Zero Detector
7 6 5 4 3 2 1 0
Rx Control
Tx Control
Input Shift Register
Internal Bus
Internal Bus
T
R
SBUF
SBUF
conditions are met, the received 9th data bit goes
into RB8, and the first 8 data bits go into SBUF.
One bit time later, whether the above conditions
were met or not, the unit goes back to looking for
a 1-to-0 transition at the RxD input.
Receive
Send
Shift
Shift
Shift
Clock
Shift
RxD
P3.0 Alt
Input
Function
RxD
P3.0 Alt
Output
Function
TxD
P3.1 Alt
Output
Function
AI06824