Hitachi H8/3937 Series Hardware Manual page 276

Bit 7: Transmit interrupt enable (TIE)
Bit 7 selects enabling or disabling of the transmit data empty interrupt request (TXI) when
transmit data is transferred from the transmit data register (TDR) to the transmit shift register
(TSR), and bit TDRE in the serial status register (SSR) is set to 1.
TXI can be released by clearing bit TDRE or bit TIE to 0.
Bit 7
TIE Description
0 Transmit data empty interrupt request (TXI) disabled
1 Transmit data empty interrupt request (TXI) enabled
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 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 Description
0 Receive data full interrupt request (RXI) and receive error interrupt
request (ERI) disabled
1 Receive data full interrupt request (RXI) and receive error interrupt
request (ERI) enabled
Bit 5: Transmit enable (TE)
Bit 5 selects enabling or disabling of the start of transmit operation.
Bit 5
TE Description
0 Transmit operation disabled*
1 Transmit operation enabled*
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, and setting of bit SPC31 or SPC32 in SPCR, to decide the transmission format
before setting bit TE to 1.
264
1
(TXD pin is I/O port)
2
(TXD pin is transmit data pin)
(initial value)
(initial value)
(initial value)