W83627DHG-PT Nuvoton Technology Corporation of America, W83627DHG-PT Datasheet - Page 179

• Manufacturer Part Number: W83627DHG-PT
• Manufacturer: Nuvoton Technology Corporation of America

Specifications of W83627DHG-PT

• Pin Count: 128
• Lead Free Status / RoHS Status: Compliant

13.3.12 ECP Operation
The host must negotiate on the parallel port to determine if the peripheral supports the ECP protocol
before ECP operation. After negotiation, it is necessary to initialize some of the port bits.
ECP address/RLE bytes or data bytes may be sent automatically by writing the ecpAFifo or ecpDFifo,
respectively.
The software must handle P1284 negotiation and all operations prior to a data transfer in SPP or PS/2
modes (000 or 001). The hardware provides an automatic control line handshake, moving data
between the FIFO and the ECP port, only in the data transfer phase (mode 011 or 010).
If the port is in mode 000 or 001, it may switch to any other mode. If the port is not in mode 000 or 001,
it can only be switched into mode 000 or 001. The direction can only be changed in mode 001.
In extended forward mode, the software should wait for the FIFO to be empty before switching back to
mode 000 or 001. In ECP reverse mode, the software should wait for all the data to be read from the
FIFO before changing back to mode 000 or 001.
ECP mode allows the transfer of normal 8-bit data or 8-bit commands. In the forward direction, normal
data are transferred when HostAck is high, and an 8-bit command is transferred when HostAck is low.
The most significant bits of the command indicate whether it is a run-length count (for compression) or
a channel address.
In the reverse direction, normal data are transferred when PeriphAck is high, and an 8-bit command is
transferred when PeriphAck is low. The most significant bit of the command is always zero.
13.3.12.1. Mode Switching
13.3.12.2. Command/Data
Select (Xflag)
NautoFd (HostAck)
nFault
(nPeriphReuqest)
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)
NAME
TYPE
O
O
O
I
I
Indicates printer on-line.
Requests a byte of data from the peripheral when it is asserted. In
the forward direction, this signal indicates whether the data lines
contain ECP address or data. 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.
W83627DHG-P/W83627DHG-PT
-169-
DESCRIPTION
Publication Release Date: July 09, 2009
Version 1.94