W83627DHG-PT Nuvoton Technology Corporation of America, W83627DHG-PT Datasheet - Page 173

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

Specifications of W83627DHG-PT

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

When EPP mode is selected, the PDx bus is in standard or bi-directional mode when no EPP read,
write, or address cycle is being executed. In this situation, all output signals are set by the SPP
Control Port and the direction is controlled by DIR of the Control Port.
A watchdog timer is required to prevent system lockup. The timer indicates that more than 10 μs have
elapsed from the start of the EPP cycle to the time WAIT# is deasserted. The current EPP cycle is
aborted when a time-out occurs. The time-out condition is indicated in status bit 0.
The EPP operates on a two-phase cycle. First, the host selects the register within the device for
subsequent operations. Second, the host performs a series of read and/or write byte operations to the
selected register. Four operations are supported on the EPP: Address Write, Data Write, Address
Read, and Data Read. All operations on the EPP device are performed asynchronously.
13.2.7.1. EPP Version 1.9 Operation
The EPP read/write operation can be completed under the following conditions:
a. If nWait is active low, the read cycle (nWrite inactive high, nDStrb/nAStrb active low) or write cycle
(nWrite active low, nDStrb/nAStrb active low) starts, proceeds normally, and is completed when nWait
goes inactive high.
b. If nWait is inactive high, the read/write cycle cannot start. It must wait until nWait changes to active
low, at which time it starts as described above.
13.2.7.2. EPP Version 1.7 Operation
The EPP read/write cycle can start without checking whether nWait is active or inactive. Once the
read/write cycle starts; however, it does not finish until nWait changes from active low to inactive high.
13.3 Extended Capabilities Parallel (ECP) Port
This port is software- and hardware-compatible with existing parallel ports, so the W83627DHG-P
parallel port may be used in standard printer mode if ECP is not required. It provides an automatic
high burst-bandwidth channel that supports DMA for ECP in both the forward (host-to-peripheral) and
reverse (peripheral-to-host) directions.
Small FIFOs are used in both forward and reverse directions to improve the maximum bandwidth
requirement. The size of the FIFO is 16 bytes. The ECP port supports an automatic handshake for the
standard parallel port to improve compatibility mode transfer speed.
The ECP port hardware supports run-length-encoded (RLE) decompression. Compression is
accomplished by counting identical bytes and transmitting an RLE byte that indicates how many times
the next byte is to be repeated. RLE compression is required; the hardware support is optional.
For more information about the ECP Protocol, please refer to the Extended Capabilities Port Protocol
and ISA Interface Standard.
The W83627DHG-P ECP supports the following modes.
MODE
000
001
010
Table 13-4 ECP Mode Description
Parallel Port Data FIFO mode
W83627DHG-P/W83627DHG-PT
PS/2 Parallel Port mode
-163-
DESCRIPTION
SPP mode
Publication Release Date: July 09, 2009
Version 1.94