VR4102 datasheet(449/701 Pages) NEC

449 / 701 page

CHAPTER 22 DSIU (DEBUG SERIAL INTERFACE UNIT)

449

22.3.2 Transmission

After the DCTS# pin value is confirmed as “1”, writing data to a transmission shift register (TXS0REG or

TXS0LREG) activates transmission via the DDOUT pin. Use the transmit complete interrupt (Dsiu_Intst0) service

routine to write the next data to TXS0REG or TXS0LREG.

Transmission enable status

The DSIU unit is always set to transmission enable status. The DCTS# pin is used when it is necessary to

confirm that the remote side is ready to receive.

Activation of transmit operation

Writing data to a transmission shift register (TXS0REG or TXS0LREG) activates the transmit operation. The

transmit data is sent in LSB-first order, beginning with the start bit. The start bit, parity bit, and stop bit(s) are

added automatically.

Transmit complete interrupt request

Once one frame of data has been sent, a transmit complete interrupt request (Dsiu_Intst0) occurs. If the next

data to be transmitted is then not written to TXS0REG or TXS0LREG, the transmit operation is halted and the

transmission rate is lowered.

Cautions 1.

Normally, the transmit complete interrupt request (Dsiu_Intst0) occurs when the TXS0REG

or TXS0LREG register is empty. However, if a reset is input, the transmit complete interrupt

request (Dsiu_Intst0) will not occur even when the transmission shift register (TXS0REG or

TXS0LREG) is empty.

Writing to either TXS0REG or TXS0LREG is prohibited during a transmit operation until

Dsiu_Intst0 occurs.

VR4102 Datasheet(PDF) 449 Page - NEC