Negotiation phase: This signal is set high in order to authorize 1284 compatibility. In nibble mode, after the host sets HostBusy (nAutoFd) high, this signal is set low in order to indicate that the transmission data is ready.

Reverse data transfer phase: This signal is set low in order to indicate to a nibble mode host that the transmission data is ready. Afterwards, this signal serves as nibble data bit 0 and then 4.

Reverse idle phase: Indicates whether or not the data is valid.

ECP mode: This signal is set low to request communications with the host. Valid in both forward and reverse directions.

nSelectln/IEEE1284active

Compatibility mode: Always low

 

A

Negotiation phase: This signal is set high at the same time that

HostBusy is low in order to request 1284 mode.

 

Reverse data transfer phase: This signal is set high to indicate that

 

the bus direction is from the printer to the host. This signal is set

 

low to terminate 1284 mode, setting the bus direction from the

 

host to the printer.

 

Reverse idle phase: Same as reverse data transfer phase

 

ECP mode: Always high. This signal is set low to terminate ECP

 

mode and return to compatibility mode.

 

GND

 

Twisted pair return signal

 

CG

 

Connected to the printer chassis. This signal and GND are

 

connected.

 

Technical Specifications A-11