LPC47M192-NW Standard Microsystems (SMSC), LPC47M192-NW Datasheet - Page 98

• Manufacturer Part Number: LPC47M192-NW
• Manufacturer: Standard Microsystems (SMSC)

Specifications of LPC47M192-NW

• Lead Free Status / RoHS Status: Compliant

Note: A threshold of 16 is equivalent to a threshold of 15. These two cases are treated the same.
Programmed I/O - Transfers from the FIFO to the Host
In the reverse direction an interrupt occurs when serviceIntr is 0 and readIntrThreshold bytes are available in the
FIFO. If at this time the FIFO is full it can be emptied completely in a single burst, otherwise readIntrThreshold bytes
may be read from the FIFO in a single burst.
An interrupt is generated when serviceIntr is 0 and the number of bytes in the FIFO is greater than or equal to (16-
<threshold>). (If the threshold = 12, then the interrupt is set whenever there are 4-16 bytes in the FIFO). The host
must respond to the request by reading data from the FIFO. This process is repeated until the last byte is transferred
out of the FIFO. If at this time the FIFO is full, it can be completely emptied in a single burst, otherwise a minimum of
(16-<threshold>) bytes may be read from the FIFO in a single burst.
Programmed I/O - Transfers from the Host to the FIFO
In the forward direction an interrupt occurs when serviceIntr is 0 and there are writeIntrThreshold or more bytes free
in the FIFO. At this time if the FIFO is empty it can be filled with a single burst before the empty bit needs to be
re-read. Otherwise it may be filled with writeIntrThreshold bytes.
An interrupt is generated when serviceIntr is 0 and the number of bytes in the FIFO is less than or equal to
<threshold>. (If the threshold = 12, then the interrupt is set whenever there are 12 or less bytes of data in the FIFO.)
The host must respond to the request by writing data to the FIFO. If at this time the FIFO is empty, it can be
completely filled in a single burst, otherwise a minimum of (16-<threshold>) bytes may be written to the FIFO in a
single burst. This process is repeated until the last byte is transferred into the FIFO.
7.9
Power management capabilities are provided for the following logical devices: floppy disk, UART 1, UART 2 and the
parallel port. For each logical device, two types of power management are provided: direct powerdown and auto
powerdown.
FDC Power Management
Direct power management is controlled by CR22. Refer to CR22 for more information.
Auto Power Management is enabled by CR23-B0. When set, this bit allows FDC to enter powerdown when all of the
following conditions have been met:
An internal timer is initiated as soon as the auto powerdown command is enabled. The part is then powered down
when all the conditions are met.
Disabling the auto powerdown mode cancels the timer and holds the FDC block out of auto powerdown.
Note: At least 8us delay should be added when exiting FDC Auto Powerdown mode.
environment is such that this delay cannot be guaranteed, the auto powerdown mode should not be used
and Direct powerdown mode should be used instead. The Direct powerdown mode requires at least 8us
delay at 250K bits/sec configuration and 4us delay at 500K bits/sec. The delay should be added so that the
internal microcontroller can prepare itself to accept commands.
DSR From Powerdown
If DSR powerdown is used when the part is in auto powerdown, the DSR powerdown will override the auto
powerdown. However, when the part is awakened from DSR powerdown, the auto powerdown will once again
become effective.
SMSC DS – LPC47M192
1.
2.
3.
4.
POWER MANAGEMENT
The motor enable pins of register 3F2H are inactive (zero).
The part must be idle; MSR=80H and INT = 0 (INT may be high even if MSR = 80H due to polling interrupts).
The head unload timer must have expired.
The Auto powerdown timer (10msec) must have timed out.
writeIntrThreshold
readIntrThreshold =(16-<threshold>) data bytes in FIFO
DATASHEET
=
(16-<threshold>) free bytes in FIFO
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If the operating
Rev. 03/30/05