5.4.4.9
ecr (Extended Control Register)
ADDRESS OFFSET = 402H
Mode = all
This register controls the extended ECP parallel port functions (Table 20).
5.4.4.9.1
BITS 7,6,5
These bits are Read/Write and select the Mode.
BIT 4 nErrIntrEn
Read/Write (Valid only in ECP Mode)
1: Disables the interrupt generated on the asserting edge of nFault.
0: Enables an interrupt pulse on the high to low edge of nFault. Note that an interrupt will be generated if nFault is
asserted (interrupting) and this bit is written from a “1” to a “0”. This prevents interrupts from being lost in the time
between the read of the ecr and the write of the ecr.
5.4.4.9.2
BIT 3 dmaEn
Read/Write
1: Enables DMA (DMA starts when serviceIntr is “0”).
0: Disables DMA unconditionally.
5.4.4.9.3
BIT 2 serviceIntr
Read/Write
1: Disables DMA and all of the service interrupts.
0: Enables one of the following 3 cases of interrupts. Once one of the 3 service interrupts has occurred serviceIntr bit
shall be set to a “1” by hardware, it must be reset to “0” to re-enable the interrupts. Writing this bit to a “1” will not
cause an interrupt.
case dmaEn=1:
During DMA (this bit is set to a “1” when terminal count is reached).
case dmaEn=0 direction=0:
This bit shall be set to “1” whenever there are writeIntrThreshold or more bytes free in the FIFO.
case dmaEn=0 direction=1:
This bit shall be set to “1” whenever there are readIntrThreshold or more valid bytes to be read from the FIFO.
5.4.4.9.4
BIT 1 full
Read only
1: The FIFO cannot accept another byte or the FIFO is completely full.
0: The FIFO has at least 1 free byte.
5.4.4.9.5
BIT 0 empty
Read only
1: The FIFO is completely empty.
0: The FIFO contains at least 1 byte of data.
Table 20 - Extended Control Register
MODE
R/W
000: Standard Parallel Port mode . In this mode the FIFO is reset and common collector drivers are
used on the control lines (nStrobe, nAutoFd, nInit and nSelectIn). Setting the direction bit will
not tri-state the output drivers in this mode.
001: PS/2 Parallel Port mode. Same as above except that direction may be used to tri-state the
data lines and reading the data register returns the value on the data lines and not the value in
the data register. All drivers have active pull-ups (push-pull).
010: Parallel Port FIFO mode. This is the same as 000 except that bytes are written or DMAed to
the FIFO. FIFO data is automatically transmitted using the standard parallel port protocol. Note
that this mode is only useful when direction is 0. All drivers have active pull-ups (push-pull).
SMSC DS – SP37E760
Page 38
Rev. 04/13/2001
SMSC [ SMSC CORPORATION ]
