SCD1284 INTEL [Intel Corporation], SCD1284 Datasheet - Page 133

• Manufacturer Part Number: SCD1284
• Description: IEEE 1284-Compatible Parallel Interface Controller with Two High-Speed Asynchronous Serial Ports
• Manufacturer: INTEL [Intel Corporation]

7.5.8
7.6
7.6.1
7.6.2
Datasheet
Register Name: RTPR
Register Description: Receive Timeout Period
Access: Read/Write
Register Name: SCHR1
Register Description: Special Character Register 1
Access: Read/Write
Register Name: SCHR2
Register Description: Special Character Register 2
Access: Read/Write
Bit 7
Bit 7
Bit 7
Receive Timeout Period Register
The RTPR determines the time period used for the NNDT (no new data timeout) and the ‘no new
data’ timeout. The timeout counter is loaded from this register whenever a new character is placed
in – or the last character is removed from – the receive FIFO. The counter decrements on each tick
of the prescaler counter (PPR). A service request is generated if the count reaches zero and:
In either case the timeout period has expired before the FIFO reaches the programmed threshold.
Special Character Registers
The four special character registers, SCHR1–SCHR4, contain the character patterns used for
various character matching and flow-control functions. Each 8-bit character is right justified, that
is, comparison occurs from right to left, and all bits are compared. Any unused bits must be ‘0’.
SCHR1 and SCHR2 serve the additional function of defining the XON and XOFF characters,
respectively, used for in-band flow control.
Special Character Register 1
SCHR1 defines the XON character.
Special Character Register 2
SCHR2 defines the XOFF character.
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Bit 6
Bit 6
Bit 6
Either an NNDT if the FIFO is empty and the NNDT is enabled, or
A Good Data service request is generated if there is data in the FIFO
Bit 5
Bit 5
Bit 5
IEEE 1284-Compatible Parallel Interface Controller — CD1284
Bit 4
Bit 4
Bit 4
Special Character 1
Special Character 2
Binary Count Value
Bit 3
Bit 3
Bit 3
Bit 2
Bit 2
Bit 2
Bit 1
Bit 1
Bit 1
8-Bit Hex Address: 1A
8-Bit Hex Address: 1B
8-Bit Hex Address: 21
Default Value: 00
Default Value: 00
Default Value: 00
Bit 0
Bit 0
Bit 0
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