A
Technical Specifications
A-9
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 k
Ω
.
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.
