W83977G Winbond Electronics Corp America, W83977G Datasheet - Page 101

• Manufacturer Part Number: W83977G
• Description: W83877TF plus KBC, CIR, RTC, Pb-free
• Manufacturer: Winbond Electronics Corp America

8.3.12
8.3.13
The host must negotiate on the parallel port to determine if the peripheral supports the ECP protocol
before ECP operation.
following are required:
ECP address/RLE bytes or data bytes may be sent automatically by writing the ecpAFifo or ecpDFifo,
respectively.
nStrobe (HostClk)
PD<7:0>
nAck (PeriphClk)
Busy (PeriphAck)
PError (nAckReverse)
Select (Xflag)
nAutoFd (HostAck)
nFault (nPeriphRequest)
nInit (nReverseRequest)
nSelectIn (ECPMode)
(a) Set direction = 0, enabling the drivers.
(b) Set strobe = 0, causing the nStrobe signal to default to the deasserted state.
(c) Set autoFd = 0, causing the nAutoFd signal to default to the deasserted state.
(d) Set mode = 011 (ECP Mode)
W83977F-A/ W83977G-A/ W83977AF-A/ W83977AG-A
ECP Pin Descriptions
ECP Operation
NAME
After negotiation, it is necessary to initialize some of the port bits. The
TYPE
I/O
O
O
O
O
I
I
I
I
I
The nStrobe registers data or address into the slave on the asserting
edge during write operations. This signal handshakes with Busy.
These signals contains address or data or RLE data.
This signal indicates valid data driven by the peripheral when asserted.
This signal handshakes with nAutoFd in reverse.
This signal deasserts to indicate that the peripheral can accept data. It
indicates whether the data lines contain ECP command information or
data in the reverse direction. When in reverse direction, normal data
are transferred when Busy (PeriphAck) is high and an 8-bit command
is transferred when it is low.
This signal is used to acknowledge a change in the direction of the
transfer (asserted = forward). The peripheral drives this signal low to
acknowledge nReverseRequest. The host relies upon nAckReverse to
determine when it is permitted to drive the data bus.
Indicates printer on line.
Requests a byte of data from the peripheral when it is asserted. This
signal indicates whether the data lines contain ECP address or data in
the forward direction. When in forward direction, normal data are
transferred when nAutoFd (HostAck) is high and an 8-bit command is
transferred when it is low.
Generates an error interrupt when it is asserted. This signal is valid
only in the forward direction. The peripheral is permitted (but not
required) to drive this pin low to request a reverse transfer during ECP
Mode.
This signal sets the transfer direction (asserted = reverse, deasserted
= forward). This pin is driven low to place the channel in the reverse
direction.
This signal is always deasserted in ECP mode.
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DESCRIPTION
Publication Release Date: May 2006
Revision 0.60