6.9.2
Extended Capabilities Parallel Port
ECP provides a number of advantages, some of which are listed below. The individual features are explained in greater
detail in the remainder of this section.
High performance half-duplex forward and reverse channel Interlocked handshake, for fast reliable transfer Optional
single byte RLE compression for improved throughput (64:1) Channel addressing for low-cost peripherals Maintains link
and data layer separation Permits the use of active output drivers permits the use of adaptive signal timing Peer-to-peer
capability.
Vocabulary
The following terms are used in this document:
assert:
When a signal asserts it transitions to a "true" state, when a signal deasserts it transitions to a "false"
state.
forward: Host to Peripheral communication.
reverse: Peripheral to Host communication
Pword:
A port word; equal in size to the width of the LPC interface. For this implementation, PWord is always
8 bits.
1
0
A high level.
A low level.
These terms may be considered synonymous:
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
PeriphClk, nAck
HostAck, nAutoFd
PeriphAck, Busy
nPeriphRequest, nFault
nReverseRequest, nInit
nAckReverse, PError
Xflag, Select
ECPMode, nSelectln
HostClk, nStrobe
Reference Document: IEEE 1284 Extended Capabilities Port Protocol and ISA Interface Standard, Rev 1.14, July 14,
1993. This document is available from Microsoft.
The bit map of the Extended Parallel Port registers is:
D7
PD7
D6
PD6
D5
PD5
D4
PD4
D3
PD3
D2
PD2
D1
PD1
D0
PD0
NOTE
data
ecpAFifo
dsr
dcr
Addr/RLE
nBusy
0
Address or RLE field
Select nFault
Direction ackIntEn SelectI
n
2
1
1
nAck
0
PError
0
nInit
0
0
autofd strobe
cFifo
ecpDFifo
tFifo
Parallel Port Data FIFO
ECP Data FIFO
Test FIFO
2
2
2
cnfgA
cnfgB
ecr
0
0
0
1
0
0
0
0
compress
intrValue
MODE
Parallel Port IRQ
Parallel Port DMA
nErrIntrEn dmaEn serviceIntr
full
empty
Note 1: These registers are available in all modes.
Note 2: All FIFOs use one common 16 byte FIFO.
Note 3: The ECP Parallel Port Config Reg B reflects the IRQ and DMA channel selected by the Configuration
Registers.
SMSC DS – LPC47M14X
Page 84
Rev. 03/19/2001
SMSC [ SMSC CORPORATION ]
