Technical Specifications
A-9
Egret
Ref. Guide
paper.bk
Rev. D
A5 size
APSPEC.FM
3/18/99
Pass 0
R
Proof Sign-off:
M.Hida
_______
K.Nishi
_______
K.Norum
_______
nACK/PtrClk/PeriphClk
Busy/PtrBusy/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 the Xflag 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).
Compatibility mode
High signal indicates that the printer is not
ready to receive data.
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.