SH7729R Datasheet, PDF (576/855 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer Super RISC engine Family/SH7700 Series

TEND Flag and TE Bit Processing: The TEND flag is set to 1 during transmission of the stop bit
of the last data. Consequently, if the TE bit is cleared to 0 immediately after setting of the TEND
flag has been confirmed, the stop bit will be in the process of transmission and will not be
transmitted normally. Therefore, the TE bit should not be cleared to 0 for at least 0.5 serial clock
cycles (or 1.5 cycles if two stop bits are used) after setting of the TEND flag is confirmed.
Receive Error Flags and Transmitter Operation (Synchronous Mode Only): When a receive
error flag (ORER, PER, or FER) is set to 1, the SCI will not start transmitting even if TDRE is set
to 1. Be sure to clear the receive error flags to 0 before starting to transmit. Note that clearing RE
to 0 does not clear the receive error flags.
Receive Data Sampling Timing and Receive Margin in Asynchronous Mode: In asynchronous
mode, the SCI operates on a base clock of 16 times the transfer rate frequency. In receiving, the
SCI synchronizes internally with the falling edge of the start bit, which it samples on the base
clock. Receive data is latched at the rising edge of the eighth base clock pulse (figure 15.24).
Base clock
16 clocks
8 clocks
0 1 2 3 4 5 6 7 8 9 10111213 1415 0 1 2 3 4 5 6 7 8 9 10111213 1415 0 1 2 3 4 5
−7.5 clocks +7.5 clocks
Receive
data (RxD)
Start bit
D0
D1
Synchro-
nization
sampling
timing
Data
sampling
timing
Figure 15.24 Receive Data Sampling Timing in Asynchronous Mode
Rev. 5.0, 09/03, page 530 of 806