Hitachi H8/3664 Hardware Manual page 270

Bit 6—Receive Interrupt Enable (RIE): Bit 6 selects enabling or disabling of the receive data
full interrupt request (RXI) and the receive error interrupt request (ERI) when receive data is
transferred from the receive shift register (RSR) to the receive data register (RDR), and bit RDRF
in the serial status register (SSR) is set to 1. There are three kinds of receive error: overrun,
framing, and parity.
RXI and ERI can be released by clearing bit RDRF or the FER, PER, or OER error flag to 0, or by
clearing bit RIE to 0.
Bit 6: RIE
0
1
Bit 5—Transmit Enable (TE): Bit 5 selects enabling or disabling of the start of transmit
operation.
Bit 5: TE
0
1
Notes: 1. Bit TDRE in SSR is fixed at 1.
2. When transmit data is written to TDR in this state, bit TDR in SSR is cleared to 0 and
serial data transmission is started. Be sure to carry out serial mode register (SMR)
settings to decide the transmission format before setting bit TE to 1.
3. When bit TXD in PMR7 is set to 1. When bit TXD is cleared to 0, the TXD pin functions
as an I/O port regardless of the TE bit setting.
Bit 4—Receive Enable (RE): Bit 4 selects enabling or disabling of the start of receive operation.
Bit 4: RE
0
1
Notes: 1. Note that the RDRF, FER, PER, and OER flags in SSR are not affected when bit RE is
cleared to 0, and retain their previous state.
2. In this state, serial data reception is started when a start bit is detected in asynchronous
mode or serial clock input is detected in synchronous mode. Be sure to carry out serial
mode register (SMR) settings to decide the reception format before setting bit RE to 1.
254
Description
Receive data full interrupt request (RXI) and receive error interrupt request
(ERI) disabled
Receive data full interrupt request (RXI) and receive error interrupt request
(ERI) enabled
Description
Transmit operation disabled
Transmit operation enabled
Description
Receive operation disabled
Receive operation enabled
(TXD pin is transmit data pin)*
1
*
(TXD pin is transmit data pin) *
2
*
(RXD pin is I/O port)
1
*
(RXD pin is receive data pin)
2
*
(Initial value)
3
(Initial value)
3
(Initial value)