ST90158-ST90135 Datasheet, PDF (160/190 Pages) STMicroelectronics – 8/16-BIT MCU FAMILY WITH UP TO 64K ROM/OTP/EPROM AND UP TO 2K RAM

ST90158 - SERIAL COMMUNICATIONS INTERFACE (SCI)
SERIAL COMMUNICATIONS INTERFACE (Cont’d)
RECEIVER BUFFER REGISTER (RXBR)
TRANSMITTER BUFFER REGISTER (TXBR)
R248 - Read only
R248 - Write only
Reset value: undefined
Reset value: undefined
7
0
7
0
RD7 RD6 RD5 RD4 RD3 RD2 RD1 RD0
TD7 TD6 TD5 TD4 TD3 TD2 TD1 TD0
Bit 7:0 = RD[7:0]: Received Data.
This register stores the data portion of the re-
ceived word. The data will be transferred from the
Receiver Shift Register into the Receiver Buffer
Register at the end of the word. All receiver inter-
rupt conditions will be updated at the time of trans-
fer. If the selected character format is less than 8
bits, unused most significant bits will forced to “1”.
Bit 7:0 = TD[7:0]: Transmit Data.
The ST9 core will load the data for transmission
into this register. The SCI will transfer the data
from the buffer into the Shift Register when availa-
ble. At the transfer, the Transmitter Buffer Register
interrupt is updated. If the selected word format is
less than 8 bits, the unused most significant bits
are not significant.
Note: RXBR and TXBR are two physically differ- Note: TXBR and RXBR are two physically differ-
ent registers located at the same address.
ent registers located at the same address.
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