Rainbow Electronics AT76C551 - Manual (Page 65)

65
AT76C551
1612D–08/01
10: No parity
11: Multi drop
• Bit 1 – RES: Parity Type
In normal parity mode this bit is used for the determination of parity. In force parity mode this
bit is forced to be the parity bit.
• Bit 0 – LSB: Reserved
Note: Default Value: 00 hex
US_MR: Mode Register
addr: 700010 hex R/W 8 bits
• Bits 7..6 – CHM[1:0] Channel Mode
00: Normal
01: Automatic echo
10: Local loop-back
11: Remote loop-back
• Bits 5..0 – Reserved
Note: Default Value: 00 hex
US_CSR: Control Status Register
addr: 700014 hex R/W 8 bits
• Bit 7 – TXE: Transmitter Empty
When set, this indicates that both the Transmit Holding Register US_THR and Transmit Shift
Register are empty.
• Bit 6 – RXTO: Receive Time-out
When set, this indicates that a receive time-out condition has occurred.
• Bit 5 – PE: Parity Error
When set, this indicates that a parity error has occurred.
• Bit 4 – FE: Framing Error
When set, this indicates that a framing error has occurred (start or stop bits has been received
with errors).
• Bit 3 – OE: Overrun Error
When set indicates that an overrun error has occurred. This means that the Receive Holding
Register is being written with a new value, while the previous one has not been read.
• Bit 2 – RBR: Receive Break
Receive Break. When set indicates that a break condition has occurred during reception
• Bit 1 – THR: Transmit Holding Register Ready
When set, this indicates that the contents of the Transmit Holding Register have been trans-
ferred to the Transmit Shift Register.