ECP Parallel (Technical)

This file is designed to give a basic overview of the port found in most newer PC computers called ECP Parallel port.

This file is not intended to be a thorough coverage of the standard. It is for informational purposes only, and is intended to give designers and hobbyists sufficient information to design their own ECP compatible devices.

Signal Descriptions:

nStrobe

This signal is registers data or address into the slave on the assering edge during .

data 0-7

Contains address, data or RLE data. Can be used in both directions.

nAck

Valid data driven by the peripheral when asserted. This signal handshakes with nAutoFd in reverse.

Busy

This signal deasserts to indicate that the peiheral can accept data. In forward direction this handshakes with nStrobe. In the reverse direction this signal indicates that the data is RLE compressed by being low.

PError

Used to acknowledge a change in the direction of transfer. High=Forward.

Select

Printer is online.

nAutoFd

Requests a byte of data from the peripheral when asserted, handshaking with nAck in the reverse direction. In the forward direction this signal indicates whether the data lines contain ECP address or data.

nFault

Generates an error interrupt when asserted.

nInit

Sets the transfer direction. High=Reverse, Low=Forward.

nSelectIn

Low in ECP mode.