OXCF950 Datasheet, PDF (52/66 Pages) Oxford Semiconductor – Single full-duplex asynchronous channel 128-byte deep transmitter / receiver FIFO

OXFORD SEMICONDUCTOR LTD.
6.11.11 Readable FCR ‘RFC’
The RFC register is located at offset 0x0F of the ICR
This read-only register returns the current state of the FCR
register (Note that FCR is write-only). This register is
included for diagnostic purposes.
6.11.12 Good-data status register ‘GDS’
The GDS register is located at offset 0x10 of the ICR
Good data status is set when the following conditions are
true:
• ISR reads level0 (no interrupt), level2 or 2a
(receiver data) or level3 (THR empty) interrupt.
• LSR[7] is clear i.e. no parity error, framing error
or break in the FIFO.
• LSR[1] is clear i.e. no overrun error has occu rred.
GDS[0]: Good Data Status
GDS[7:1]: Reserved
6.11.13 DMA Status Register ‘DMS’
The DMS register is located at offset 0x11 of the ICR. This
register is unused in the OXCF950 except for test
purposes.
6.11.14 Port Index Register ‘PIX’
The PIX register is located at offset 0x12 of the ICR. This
read-only register gives the UART index. For a single
channel device such as the OXCF950 this reads ‘0’.
6.11.15 Clock Alteration Register ‘CKA’
The CKA register is located at offset 0x13 of the ICR. This
register adds additional clock control mainly for
isochronous and embedded applications. The register is
effectively an enhancement to the CKS register.
This register is cleared to 0x00 after a hardware reset to
maintain compatibility with 16C550, but is unaffected by
software reset. This allows the user to select a clock mode
and then reset the channel to work-around any timing
glitches.
CKA[0]: Invert internal RX Clock
OXCF950 rev B DATA SHEET V 1.0
This allows the sense of the receiver clock to be inverted.
The main use for this would be to invert an isochronous
input clock so the falling edge were used for sampling
rather than the rising edge.
CKA[1]: Invert internal TX clock
This allows the sense of the transmitter clock to be
inverted. The main use for this would be to invert an
isochronous input clock so the rising edge were used for
data output rather than the falling edge.
CKA[2]: Invert DTR
This allows the DTR output signal to be inverted, which is
most likely to be useful when DTR is selected as being the
transmitter clock for isochronous applications.
6.11.16 Misc Data Register
The Misc Data Register allows the user to select access to
either the local configuration registers or the local bus,
when the OXCF950 is operating in Local Bus Mode. When
the OXCF950 is operating in Generic mode (8 byte
address space), it causes the local configuration registers
to overlay the UART registers. It has no effect when the
OXCF950 is operating in Normal Mode. When exiting
generic mode access to configuration registers, b0 is
cleared automatically.
Table 40 describes the MDR register operation.
MDR Description
Bits
7:1
Reserved for future use : ‘0’ must be written to
these.
0
Active low Local Bus Enable (Local Bus
mode only).
Setting this bit to ‘0’ allows access to local bus.
Setting this bit to ‘1’ allows access to local
configuration registers.
Table 40: MDR operation
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