nAutoFd/HostBusy/HostAck

Compatibility mode:

Not used.

negotiation phase:

In order to request 1284 mode, this signal is set

 

low and IEEE 1284active (nSelectIn) is set high.

 

Afterwards, this signal is set high whenPtrClk

 

(nAck) is set low.

reverse data transfer phase: In nibble mode, setting this signal low indicates to the printer that the host is ready to receive data. When this signal is subsequently set high, it indicates that the host received the data.

reverse idle phase:

This signal is set high in response to a PtrClk

 

(nAck) low pulse in order to return to be reverse

 

data phase. If this signal is set high at the same

 

time that IEEE 1284active (nSelectIn) is set low,

 

the IEEE 1284 idle phase is aborted and the

 

interface returns to compatibility mode.

ECP mode:

Used for reverse direction flow control. Also

 

used for handshaking via PeriphClk (nAck).

NC

Not used.

PeripheralLogicHigh

Pull up to + 5 V with 3.9 kΩ .

A

nInit/nReverseRequest

Compatibility mode:

When a low signal is detected, the printer is

 

deemed to be BUSY until the low signal is

 

released.

negotiation phase:

Always high.

reverse data transfer phase: Always high.

ECP mode:

Low when switching to reverse direction. The

 

peripheral device has permission to drive the

 

data signal only when this signal is low and

 

1284active is high.

Technical Specifications

A-9