C509-L_97 Datasheet, PDF (179/290 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

On-Chip Peripheral Components
C509-L
RB80/RB81, and to set RI0/RI1, will be generated if, and only if, the following conditions are met at
the time the final shift pulse is generated:
1) RI0/RI1 = 0, and
2) either SM20/SM21 = 0 or the received 9th data bit = 1
lf either one of these two conditions is not met, the received frame is irretrievably lost, and RI0/Rl1
is not set. lf both conditions are met, the received 9th data bit goes into RB80/RB81, the first 8 data
bits go into S0BUF/S1BUF. One bit time later, no matter whether the above conditions are met or
not, the unit goes back to look for a 1-to-0 transition at the RXD0/RXD1 input.
Note that the value of the received stop bit is irrelevant to S0BUF/S1BUF, RB80/RB81, or RI0/Rl1.
Semiconductor Group
6-101
1997-10-01