H8SLASH3003 datasheet(489/715 Pages) RENESAS

489 / 715 page

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

recognizes that TDR contains new data, and loads this data from TDR into TSR.

•

After loading the data from TDR into TSR, the SCI sets the TDRE flag to 1 and starts

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).

•

The SCI checks the TDRE flag when it outputs the MSB (bit 7). If the TDRE flag is 0, the

SCI 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 in SCR is set to 1, a transmit-end

interrupt (TEI) is requested at this time.

•

After the end of serial transmission, the SCK pin is held in a constant state.

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H8/3003 Datasheet(PDF) 489 Page - Renesas Technology Corp