HT45B0F

Rev. 1.00

10

June 7, 2011

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.

The UCR2 register is the second of the UART control registers and serves several purposes. One of its main func-

tions 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

76543210

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

00001011

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

²0², 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

²1² and the UARTEN bit is also equal to ²1², 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

²0², 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

²1² and the UARTEN bit is also equal to ²1², 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.

Bit 5

BRGH: Baud Rate speed selection

0: low speed baud rate

1: high speed baud rate

The bit named BRGH selects the high or low speed mode of the Baud Rate Generator. This bit,

together with the value placed in the baud rate register BRG, controls the Baud Rate of the

UART. If this bit is equal to

²1², the high speed mode is selected. If the bit is equal to ²0²,

the low speed mode is selected.

Bit 4

ADDEN: Address detect function enable control

0: address detect function is disabled

1: address detect function is enabled

The bit named ADDEN is the address detect function enable control bit. When this bit is equal to

²1², the address detect function is enabled. When it occurs, if the 8th bit, which corresponds to

RX7 if BNO=0 or the 9th bit, which corresponds to RX8 if BNO=1, has a value of

²1²,

then the received word will be identified as an address, rather than data. If the corresponding

interrupt is enabled, an interrupt request will be generated each time the received word has the

address bit set, which is the 8th or 9th bit depending on the value of BNO. If the address bit

known as the 8th or 9th bit of the received word is

²0² with the address detect function being

enabled, an interrupt will not be generated and the received data will be discarded.