3803_03 Datasheet, PDF (60/136 Pages) Renesas Technology Corp – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

3803/3804 Group
[Serial I/O3 Control Register (SIO3CON)]
003216
The serial I/O3 control register consists of eight control bits for the
serial I/O3 function.
[UART3 Control Register (UART3CON)]
003316
The UART control register consists of four control bits (bits 0 to 3)
which are valid when asynchronous serial I/O is selected and set
the data format of an data transfer, and one bit (bit 4) which is al-
ways valid and sets the output structure of the P35/TXD3 pin.
[Serial I/O3 Status Register (SIO3STS)] 003116
The read-only serial I/O3 status register consists of seven flags
(bits 0 to 6) which indicate the operating status of the serial I/O3
function and various errors.
Three of the flags (bits 4 to 6) are valid only in UART mode.
The receive buffer full flag (bit 1) is cleared to “0” when the receive
buffer register is read.
If there is an error, it is detected at the same time that data is
transferred from the receive shift register to the receive buffer reg-
ister, and the receive buffer full flag is set. A write to the serial I/O3
status register clears all the error flags OE, PE, FE, and SE (bit 3
to bit 6, respectively). Writing “0” to the serial I/O3 enable bit SIOE
(bit 7 of the serial I/O3 control register) also clears all the status
flags, including the error flags.
Bits 0 to 6 of the serial I/O3 status register are initialized to “0” at
reset, but if the transmit enable bit (bit 4) of the serial I/O3 control
register has been set to “1”, the transmit shift completion flag (bit
2) and the transmit buffer empty flag (bit 0) become “1”.
[Transmit Buffer Register 3/Receive Buffer
Register 3 (TB3/RB3)] 003016
The transmit buffer register 3 and the receive buffer register 3 are
located at the same address. The transmit buffer is write-only and
the receive buffer is read-only. If a character bit length is 7 bits, the
MSB of data stored in the receive buffer is “0”.
[Baud Rate Generator 3 (BRG3)] 002F16
The baud rate generator determines the baud rate for serial trans-
fer.
The baud rate generator divides the frequency of the count source
by 1/(n + 1), where n is the value written to the baud rate genera-
tor.
Rev.4.01 Nov 14, 2003 page 60 of 136