h8s-2158 Renesas Electronics Corporation., h8s-2158 Datasheet - Page 477

• Manufacturer Part Number: h8s-2158
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2100 Series
• Manufacturer: Renesas Electronics Corporation.

16.4.6
Figure 16.9 shows an example of the operation for transmission in asynchronous mode. In
transmission, the SCI operates as described below.
1. The SCI monitors the TDRE flag in SSR, and if it is cleared to 0, recognizes that data has been
2. After transferring data from TDR to TSR, the SCI sets the TDRE flag to 1 and starts
3. Data is sent from the TxD pin in the following order: start bit, transmit data, parity bit or
4. The SCI checks the TDRE flag at the timing for sending the stop bit.
5. If the TDRE flag is 0, the data is transferred from TDR to TSR, the stop bit is sent, and then
6. If the TDRE flag is 1, the TEND flag in SSR is set to 1, the stop bit is sent, and then the “mark
Figure 16.10 shows a sample flowchart for transmission in asynchronous mode.
written to TDR, and transfers the data from TDR to TSR.
transmission. If the TIE bit in SCR is set to 1 at this time, a transmit data empty interrupt
request (TXI) is generated. Because the TXI interrupt routine writes the next transmit data to
TDR before transmission of the current transmit data has finished, continuous transmission can
be enabled.
multiprocessor bit (may be omitted depending on the format), and stop bit.
serial transmission of the next frame is started.
state” is entered in which 1 is output. If the TEIE bit in SCR is set to 1 at this time, a TEI
interrupt request is generated.
TXI interrupt
request generated
TDRE
TEND
Figure 16.9 Example of Operation in Transmission in Asynchronous Mode
Serial Data Transmission (Asynchronous Mode)
1
Start
bit
0
Data written to TDR and
TDRE flag cleared to 0 in
TXI interrupt service routine
D0
(Example with 8-Bit Data, Parity, One Stop Bit)
D1
1 frame
Data
Section 16 Serial Communication Interface (SCI, IrDA, and CRC)
D7
Parity
bit
0/1
TXI interrupt
request generated
Stop
bit
1
Start
bit
0
D0
Rev. 3.00 Jan 25, 2006 page 425 of 872
D1
Data
D7
Parity
bit
TEI interrupt
request generated
0/1
Stop
bit
REJ09B0286-0300
1
Idle state
(mark state)
1