HD6413008F RENESAS [Renesas Technology Corp], HD6413008F Datasheet - Page 416

• Manufacturer Part Number: HD6413008F
• Description: Renesas 16-Bit Single-Chip Microcomputer H8 Family/H8/300H Series
• Manufacturer: RENESAS [Renesas Technology Corp]

12. Serial Communication Interface
In transmitting serial data, the SCI operates as follows.
• The SCI monitors the TDRE flag in SSR. When the TDRE flag is cleared to 0, the SCI
• After loading the data from TDR to TSR, the SCI sets the TDRE flag to 1 and starts
• The SCI checks the TDRE flag when it outputs the MSB (bit 7). If the TDRE flag is 0, the SCI
• After the end of serial transmission, the SCK pin is held in a constant state.
Figure 12.17 shows an example of SCI transmit operation.
Rev.4.00 Aug. 20, 2007 Page 372 of 638
REJ09B0395-0400
Serial clock
Serial data
TDRE
TEND
recognizes that TDR contains new data, and loads this data from TDR into TSR.
transmitting. If the TIE bit is set to 1 in SCR, the SCI requests a transmit-data-empty interrupt
(TXI) at this time.
If clock output is selected, the SCI outputs eight serial clock pulses. If an external clock source
is selected, the SCI outputs data in synchronization with the input clock. Data is output from
the TxD pin in order from LSB (bit 0) to MSB (bit 7).
loads data from TDR into TSR and begins serial transmission of the next frame. If the TDRE
flag is 1, the SCI sets the TEND flag to 1 in SSR, and after transmitting the MSB, holds the
TxD pin in the MSB state. If the TEIE bit is set to 1 in SCR, a transmit-end interrupt (TEI) is
requested at this time
TXI interrupt
request
Figure 12.17 Example of SCI Transmit Operation
TXI interrupt handler
writes data in TDR
and clears TDRE
flag to 0
Bit 0
Transmit direction
Bit 1
1 frame
TXI interrupt
request
Bit 7
Bit 0
Bit 1
Bit 6
TEI interrupt
request
Bit 7