H8SX1663 datasheet(793/1158 Pages) RENESAS

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Section 15 Serial Communication Interface (SCI, IrDA, CRC)

Rev.1.00 Jun. 07, 2006 Page 741 of 1102

REJ09B0294-0100

15.10.7

SCI Operations during Power-Down State

Transmission: Before specifying the module stop state or making a transition to software standby

mode, stop the transmit operations (TE = TIE = TEIE = 0). TSR, TDR, and SSR are reset. The

states of the output pins in the module stop state or in software standby mode depend on the port

settings, and the pins output a high-level signal after cancellation. If the transition is made during

data transmission, the data being transmitted will be undefined.

To transmit data in the same transmission mode after cancellation of the power-down state, set the

TE bit to 1, read SSR, write to TDR, clear TDRE in this order, and then start transmission. To

transmit data in a different transmission mode, initialize the SCI first.

Figure 15.39 shows a sample flowchart for transition to software standby mode during

transmission. Figures 15.40 and 15.41 show the port pin states during transition to software

standby mode.

Before specifying the module stop state or making a transition to software standby mode from the

transmission mode using DTC transfer, stop all transmit operations (TE = TIE = TEIE = 0).

Setting the TE and TIE bits to 1 after cancellation sets the TXI flag to start transmission using the

DTC.

Reception: Before specifying the module stop state or making a transition to software standby

mode, stop the receive operations (RE = 0). RSR, RDR, and SSR are reset. If transition is made

during data reception, the data being received will be invalid.

To receive data in the same reception mode after cancellation of the power-down state, set the RE

bit to 1, and then start reception. To receive data in a different reception mode, initialize the SCI

first.

For using the IrDA function, set the IrE bit in addition to setting the RE bit.

Figure 15.42 shows a sample flowchart for mode transition during reception.

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