VT82C686B

Manufacturer Part NumberVT82C686B
ManufacturerETC-unknow
VT82C686B datasheet
 


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Serial Port 2 Registers
These registers are located at I/O ports which are offsets from
“COM2Base” (index E8h of the Super-I/O configuration
registers). COM2Base is typically set to allow these ports to
be accessed at the standard serial port 2 address range of 2F8-
2FFh.
Port COM2Base+0 – Transmit / Receive Buffer ............ RW
7-0
Serial Data
Port COM2Base+1 – Interrupt Enable ........................... RW
7-4
Undefined ..........................................always read 0
3
Interrupt on Handshake Input State Change
2
Intr on Parity, Overrun, Framing Error or Break
1
Interrupt on Transmit Buffer Empty
0
Interrupt on Receive Data Ready
Port COM2Base+1-0 – Baud Rate Generator Divisor ... RW
15-0 Divisor Value for Baud Rate Generator
Baud Rate = 115,200 / Divisor
(e.g., setting this register to 1 selects 115.2 Kbaud)
Port COM2Base+2 – Interrupt Status ............................. RO
7-3
Undefined ..........................................always read 0
2-1
Interrupt ID (0=highest priority)
00 Priority 3 (Handshake Input Changed State)
01 Priority 2 (Transmit Buffer Empty)
10 Priority 1 (Data Received)
11 Priority 0 (Serialization Error or Break)
0
Interrupt Pending
0
Interrupt Pending
1
No Interrupt Pending
Port COM2Base+2 – FIFO Control ............................... WO
Port COM2Base+3 – UART Control ............................... RW
7
Divisor Latch Access
0
Access xmit / rcv & int enable regs at 0-1
1
Access baud rate generator divisor latch at 0-1
6
Break
0
Break condition off
1
Break condition on
5-3
Parity
000 None
001 Odd
011 Even
101 Mark
111 Space
2
Stop Bits
0
1
1
2
1-0
Data Bits
00 5
01 6
10 7
11 8
Revision 1.71 June 9, 2000
Port COM2Base+4 – Handshake Control ...................... RW
7-5
Undefined
......................................... always read 0
4
Loopback Check
0
Normal operation
1
Loopback enable
3
General Purpose Output 2 (unused in 82C686B)
2
General Purpose Output 1 (unused in 82C686B)
1
Request To Send
0
Disable
1
Enable
0
Data Terminal Ready
0
Disable
1
Enable
Port COM2Base+5 – UART Status ................................. RW
7
Undefined
......................................... always read 0
6
Transmitter Empty
0
1 byte in transmit hold or transmit shift register
1
0 bytes transmit hold and transmit shift regs
5
Transmit Buffer Empty
0
1 byte in transmit hold register
1
Transmit hold register empty
4
Break Detected
0
No break detected
1
Break detected
3
Framing Error Detected
0
No error
1
Error
2
Parity Error Detected
0
No error
1
Error
1
Overrun Error Detected
0
No error
1
Error
0
Received Data Ready
0
No received data available
1
Received data in receiver buffer register
Port COM2Base+6 – Handshake Status ......................... RW
7
DCD Status (1=Active, 0=Inactive)
6
RI Status (1=Active, 0=Inactive)
5
DSR Status (1=Active, 0=Inactive)
4
CTS Status (1=Active, 0=Inactive)
3
DCD Changed (1=Changed Since Last Read)
2
RI Changed (1=Changed Since Last Read)
1
DSR Changed (1=Changed Since Last Read)
0
CTS Changed (1=Changed Since Last Read)
Port COM2Base+7 – Scratchpad .................................... RW
7
Scratchpad Data
-51-
Register Descriptions - Super-I/O I/O Ports
VT82C686B