Holtek BS83B24C Manual page 125

BS83B24C/BS83C40C
Touch Flash MCU
• UUCR1 Register
The UUCR1 register together with the UUCR2 register are the two UART control registers that are
used to set the various options for the UART function, such as overall on/off control, parity control,
data transfer bit length etc. Further explanation on each of the bits is given below:
Bit 7
Name UREN
R/W R/W
POR 0
UREN: UART function enable control
Bit 7
0: Disable UART. TX and RX pins are in a floating state
1: Enable UART. TX and RX pins function as UART pins
The UREN bit is the UART enable bit. When this bit is equal to "0", the UART will be
disabled and the RX pin as well as the TX pin will be set in a floating state. When the
bit is equal to "1", the UART will be enabled if the UMD bit is set and the TX and RX
pins will function as defined by the UTXEN and URXEN enable control bits.
When the UART is disabled, it will empty the buffer so any character remaining in the
buffer will be discarded. In addition, the value of the baud rate counter will be reset.
If the UART is disabled, all error and status flags will be reset. Also the UTXEN,
URXEN, UTXBRK, URXIF, UOERR, UFERR, UPERR and UNF bits will be cleared
to 0, while the UTIDLE, UTXIF and URIDLE bits will be set. Other control bits in
UUCR1, UUCR2 and UBRG registers will remain unaffected. If the UART is active
and the UREN bit is cleared to 0, all pending transmissions and receptions will be
terminated and the module will be reset as defined above. When the UART is re-
enabled, it will restart in the same configuration.
Bit 6 UBNO: Number of data transfer bits selection
0: 8-bit data transfer
1: 9-bit data transfer
This bit is used to select the data length format, which can have a choice of either
8-bit or 9-bit format. When this bit is equal to "1", a 9-bit data length format will be
selected. If the bit is equal to "0", then an 8-bit data length format will be selected. If
9-bit data length format is selected, then bits URX8 and UTX8 will be used to store
the 9th bit of the received and transmitted data respectively.
UPREN: Parity function enable control
Bit 5
0: Parity function is disabled
1: Parity function is enabled
This is the parity enable bit. When this bit is equal to "1", the parity function will be
enabled. If the bit is equal to "0", then the parity function will be disabled.
Bit 4 UPRT: Parity type selection bit
0: Even parity for parity generator
1: Odd parity for parity generator
This bit is the parity type selection bit. When this bit is equal to "1", odd parity type
will be selected. If the bit is equal to "0", then even parity type will be selected.
Bit 3 USTOPS: Number of Stop bits selection
0: One stop bit format is used
1: Two stop bits format is used
This bit determines if one or two stop bits are to be used. When this bit is equal to "1",
two stop bits are used. If this bit is equal to "0", then only one stop bit is used.
Bit 2 UTXBRK: Transmit break character
0: No break character is transmitted
1: Break characters transmit
The UTXBRK 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 UTXBRK bit is reset.
Rev. 1.00
6 5 4
UBNO UPREN UPRT
R/W R/W R/W
0 0 0
1�5
3 2 1
USTOPS UTXBRK URX�
R/W R/W R
0 0 x
"x": Unknown
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0
UTX�
W
0