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509
0
1
1
1
0/1
0
1
TDRE
TEND
Parity
bit
Parity
bit
Serial
data
Start
bit
Data
Stop
bit
Start
bit
Data
Stop
bit
Idle
(marking
state)
TxI
interrupt
request
TxI interrupt
handler writes
data in TDR
and clears
TDRE to 0
TxI
request
TEI interrupt request
1 frame
D0
D1
D7
D0
D1
D7
0/1
Example: 8-bit data with parity and one stop bit
Figure 14.6 SCI Transmit Operation in Asynchronous Mode
Receiving Serial Data (Asynchronous Mode): Figures 14.7 and 14.8 show a sample flowchart
for receiving serial data. The procedure is as follows (the steps correspond to the numbers in the
flowchart).
1.SCI initialization: Set the RxD pin using the PFC.
2.Receive error handling and break detection: If a receive error occurs, read the ORER, PER,
and FER bits of the SSR to identify the error. After executing the necessary error handling,
clear ORER, PER, and FER all to 0. Receiving cannot resume if ORER, PER, or FER remain
set to 1. When a framing error occurs, the RxD pin can be read to detect the break state.
3.SCI status check and receive-data read: Read the serial status register (SSR), check that RDRF
is set to 1, then read receive data from the receive data register (RDR) and clear RDRF to 0.
The RxI interrupt can also be used to determine if the RDRF bit has changed from 0 to 1.
4.Continue receiving serial data: Read the RDR and RDRF bit and clear RDRF to 0 before the
stop bit of the current frame is received. If the DMAC or the DTC is started by a receive-data-
full interrupt (RxI) to read RDR, the RDRF bit is cleared automatically so this step is
unnecessary.
Содержание SH7041 Series
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