nACK/PtrClk/PeriphClk

All modes:

DATA 8 is the MSB, DATA 1 is the LSB.

Compatibility mode:

Acknowledgment low pulse in order to indicate

 

that data was transferred from the host.

negotiation phase:

Low signal indicates IEEE 1284 is supported; set

 

to high afterwards to indicate that theXflag and

 

“data available” flag are valid.

reverse data transfer phase: In nibble mode, a low signal indicates that the

 

nibble data is valid.

reverse idle phase:

When switched from low to high, generates an

 

interrupt that notifies the host that there is data

 

available.

ECP mode:

Used to transfer data from the printer to the

 

host with handshaking via HostAck (nAutoFd).

Busy/PtrBusy/PeriphClk

 

 

Compatibility mode:

High signal indicates that the printer is not

 

ready to receive data.

A

negotiation phase:

Reflects the BUSY status of the forward channel.

 

 

reverse data transfer phase: In nibble mode, this signal serves as nibble data

 

bit 3 and then 7.

reverse idle phase:

Reflects the BUSY status of the forward channel.

ECP mode:

Used for forward direction flow control. In

 

reverse direction, this signal is used as a ninth

data bit that indicates whether the data signals indicate a command or data.

Technical Specifications

A-7