Owner manual

68
AT76C551
1612D–08/01
• Bit 5 – CD: Carrier Detect
Active high. This bit is the compliment of the CD input pin.
• Bit 4 – CTS: Clear To Send
Active high. This bit is the compliment of the CTS input pin.
• Bit 3 – DSR Change
Active high
Logic 0: No DSR change
Logic 1: The DSR input pin has changed state since the last time it was read. An interrupt will
be generated.
• Bit 2 – RI: Ring Indicator Change
Active high
Logic 0: No RI change
Logic 1: The RI input pin has changed state since the last time it was read. An interrupt will be
generated.
• Bit 1 – CD: Change
Active high
Logic 0: No CD change
Logic 1: The CD input pin has changed state since the last time it was read. An interrupt will be
generated.
• Bit 0 – CTS Change
Active high
Logic 0: No CTS change
Logic 1: The CTS input pin has changed state since the last time it was read. An interrupt will
be generated.
Note: Default Value: 00 hex
US_MCO: Modem Control Outputs
addr: 70002C hex W 8 bits
• Bits 7..5 – Reserved
• Bit 1 – RTS
Control RTS output pin:
Logic 1: Force RTS output pin to a logic
Logic 0: Force RTS output pin to a logic 0
• Bit 0 – DTR
Control DTR output pin:
Logic 1: Force DTR output pin to a logic 1
Logic 0: Force DTR output pin to a logic 0
Note: Default Value: 00 hex