
Rev. 2.50
244
��ne 22� 20��
Rev. 2.50
245
��ne 22� 20��
HT66F20/HT66F30/HT66F40/HT66F50/HT66F60
HT66FU30/HT66FU40/HT66FU50/HT66FU60
A/D Flash MCU with EEPROM
HT66F20/HT66F30/HT66F40/HT66F50/HT66F60
HT66FU30/HT66FU40/HT66FU50/HT66FU60
A/D Flash MCU with EEPROM
Bit 2
TXBRK
: Transmit break character
0: No break character is transmitted
1: Break characters transmit
The TXBRK bit is the Transmit Break Character bit. When this bit is 0, there are
no break characters and the TX pin operates normally. When the bit is 1, there are
transmit break characters and the transmitter will send logic zeros. When this bit is
equal to 1, after the buffered data has been transmitted, the transmitter output is held
low for a minimum of a 13-bit length and until the TXBRK bit is reset.
Bit 1
RX8
: Receive data bit 8 for 9-bit data transfer format (read only)
This bit is only used if 9-bit data transfers are used, in which case this bit location will
store the 9th bit of the received data known as RX8. The BNO bit is used to determine
whether data transfers are in 8-bit or 9-bit format.
Bit 0
TX8
: Transmit data bit 8 for 9-bit data transfer format (write only)
This bit is only used if 9-bit data transfers are used, in which case this bit location
will store the 9th bit of the transmitted data known as TX8. The BNO bit is used to
determine whether data transfers are in 8-bit or 9-bit format.
UCR2 register
The UCR2 register is the second of the UART control registers and serves several purposes. One
of its main functions is to control the basic enable/disable operation if the UART Transmitter and
Receiver as well as enabling the various UART interrupt sources. The register also serves to control
the baud rate speed, receiver wake-up function enable and the address detect function enable.
Further explanation on each of the bits is given below:
Bit
7
6
5
4
3
2
1
0
Name
TXEN
RXEN
BRGH
ADDEN
WAKE
RIE
TIIE
TEIE
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R
W
POR
0
0
0
0
�
0
�
�
Bit 7
TXEN
: UART Transmitter enable control
0: UART transmitter is disabled
1: UART transmitter is enabled
The bit named TXEN is the Transmitter Enable Bit. When this bit is equal to 0, the
transmitter will be disabled with any pending data transmissions being aborted. In
addition the buffers will be reset. In this situation the TX pin will be in the state of
high impedance. If the TXEN bit is equal to 1 and the UARTEN bit is also equal to
1, the transmitter will be enabled and the TX pin will be controlled by the UART.
Clearing the TXEN bit during a transmission will cause the data transmission to be
aborted and will reset the transmitter. If this situation occurs, the TX pin will be in the
state of high impedance.
Bit 6
RXEN
: UART Receiver enable control
0: UART receiver is disabled
1: UART receiver is enabled
The bit named RXEN is the Receiver Enable Bit. When this bit is equal to 0, the
receiver will be disabled with any pending data receptions being aborted. In addition
the receive buffers will be reset. In this situation the RX pin will be in the state of high
impedance. If the RXEN bit is equal to 1 and the UARTEN bit is also equal to 1, the
receiver will be enabled and the RX pin will be controlled by the UART. Clearing the
RXEN bit during a reception will cause the data reception to be aborted and will reset
the receiver. If this situation occurs, the RX pin will be in the state of high impedance.