PC97307 datasheet(121/218 Pages) NSC

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Parallel Port (Logical Device 4)

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6.5.3

ECP Data Register (DATAR),

Bits 7-5 of ECR = 000 or 001, Offset 000h

The ECP Data Register (DATAR) register is the same as

the DTR register (see Section 6.2.2), except that a read al-

ways returns the values of the PD7-0 signals instead of the

FIGURE 6-17. DATAR Register Bitmap

6.5.4

ECP Address FIFO (AFIFO) Register,

Bits 7-5 of ECR = 011, Offset 000h

The ECP Address FIFO Register (AFIFO) is write only. In

the forward direction (when bit 5 of DCR is 0) a byte written

into this register is pushed into the FIFO and tagged as a

command.

Reading this register returns undefined contents. Writing to

this register in a backward direction (when bit 5 of DCR is 1)

has no effect and the data is ignored.

FIGURE 6-18. AFIFO Register Bitmap

76543210

Reset

Required

ECP Data Register

(DATAR)

Offset 000h

Bits 7-5 of ECR = 000 or 001

Data Bits

76543210

Reset

Required

ECP Address Register

(AFIFO)

Offset 000h

Bits 7-5 of ECR = 011

Address Bits

6.5.5

ECP Status Register (DSR), Offset 001h

This read-only register displays device status. Writes to this

DSR have no effect and the data is ignored.

This register should not be confused with the DSR register

of the Floppy Disk Controller (FDC).

FIGURE 6-19. ECP DSR Register Bitmap

Bits 0 - EPP Time-Out Status

In EPP modes only, this is the time-out status bit. In all

other modes this bit has no function and has the con-

stant value 1.

This bit is cleared when an EPP mode is enabled.

Thereafter, this bit is set to 1 when a time-out occurs in

an EPP cycle and is cleared when DSR is read.

In EPP modes:

0 - An EPP mode is set. No time-out occurred since

DSR was last read.

1 - Time-out occurred on EPP cycle (minimum of 10

µsec). (Default)

Bits 2,1 - Reserved

These bits are reserved and are always 1.

Bit 3 - ERR Status

This bit reflects the status of the ERR signal.

0 - Printer error.

1 - No printer error.

Bit 4 - SLCT Status

This bit reflects the status of the Select signal. The print-

er sets this signal high when it is online and selected

0 - Printer not selected. (Default)

1 - Printer selected and on-line.

Bit 5 - PE Status

This bit reflects the status of the Paper End (PE) signal.

0 - Paper not ended.

1 - No paper in printer.

Bit 6 - ACK Status

This bit reflects the status of the ACK signal. This signal

is pulsed low after a character is received.

0 - Character received.

1 - No character received. (Default)

76543210

Reset

Required

ECP Status Register

(DSR)

Offset 001h

Reserved

SLCT Status

PE Status

ACK Status

Printer Status

EPP Time-Out Status

Reserved

ERR Status

PC97307 Datasheet(PDF) 121 Page - National Semiconductor (TI)

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