
Rev. 1.20
140
November 20, 2019
Rev. 1.20
141
November 20, 2019
HT66F2740
12V High Current Flash MCU
HT66F2740
12V High Current Flash MCU
Bit 4
UOERR
: Overrun error flag
0: No overrun error is detected
1: Overrun error is detected
The UOERR flag is the overrun error flag which indicates when the receiver buffer has
overflowed. When this read only flag is “0”, it indicates that there is no overrun error.
When the flag is “1”, it indicates that an overrun error occurs which will inhibit further
transfers to the UTXR_RXR receive data register. The flag is cleared by a software
sequence, which is a read to the status register UUSR followed by an access to the
UTXR_RXR data register.
Bit 3
URIDLE
: Receiver status
0: Data reception is in progress (Data being received)
1: No data reception is in progress (Receiver is idle)
The URIDLE flag is the receiver status flag. When this read only flag is “0”, it
indicates that the receiver is between the initial detection of the start bit and the
completion of the stop bit. When the flag is “1”, it indicates that the receiver is idle.
Between the completion of the stop bit and the detection of the next start bit, the
URIDLE bit is “1” indicating that the UART receiver is idle and the RX pin stays in
logic high condition.
Bit 2
URXIF
: Receive UTXR_RXR data register status
0: UTXR_RXR data register is empty
1: UTXR_RXR data register has available data
The URXIF flag is the receive data register status flag. When this read only flag is
“0”, it indicates that the UTXR_RXR read data register is empty. When the flag is
“1”, it indicates that the UTXR_RXR read data register contains new data. When the
contents of the shift register are transferred to the UTXR_RXR register, an interrupt
is generated if URIE=1 in the UUCR2 register. If one or more errors are detected in
the received word, the appropriate receive-related flags UNF, UFERR, and/or UPERR
are set within the same clock cycle. The URXIF flag will eventually be cleared when
the UUSR register is read with URXIF set, followed by a read from the UTXR_RXR
register, and if the UTXR_RXR register has no more new data available.
Bit 1
UTIDLE
: Transmission idle
0: Data transmission is in progress (Data being transmitted)
1: No data transmission is in progress (Transmitter is idle)
The UTIDLE flag is known as the transmission complete flag. When this read only
flag is “0”, it indicates that a transmission is in progress. This flag will be set high
when the UTXIF flag is “1” and when there is no transmit data or break character
being transmitted. When UTIDLE is equal to “1”, the TX pin becomes idle with the
pin state in logic high condition. The UTIDLE flag is cleared by reading the UUSR
register with UTIDLE set and then writing to the UTXR_RXR register. The flag is not
generated when a data character or a break is queued and ready to be sent.
Bit 0
UTXIF
: Transmit UTXR_RXR data register status
0: Character is not transferred to the transmit shift register
1: Character has transferred to the transmit shift register (UTXR_RXR data register
is empty)
The UTXIF flag is the transmit data register empty flag. When this read only flag is “0”,
it indicates that the character is not transferred to the transmitter shift register. When
the flag is “1”, it indicates that the transmitter shift register has received a character
from the UTXR_RXR data register. The UTXIF flag is cleared by reading the UART
status register (UUSR) with UTXIF set and then writing to the UTXR_RXR data
register. Note that when the UTXEN bit is set, the UTXIF flag bit will also be set since
the transmit data register is not yet full.