SMSC DS – LPC47M14X
Page 84
Rev. 03/19/2001
6.9.2
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
8 bits.
1
A high level.
0
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
D6
D5
D4
Extended Capabilities Parallel Port
is always
D3
D2
D1
D0
NOTE
data
PD7
PD6
PD5
PD4
PD3
PD2
PD1
PD0
ecpAFifo
Addr/RLE
Address or RLE field
2
dsr
nBusy
nAck
PError
Select
nFault
0
0
0
1
dcr
0
0
Direction
ackIntEn
SelectI
n
nInit
autofd
strobe
1
cFifo
Parallel Port Data FIFO
2
ecpDFifo
ECP Data FIFO
2
tFifo
Test FIFO
2
cnfgA
0
0
0
1
0
0
0
0
cnfgB
compress
intrValue
Parallel Port IRQ
Parallel Port DMA
ecr
MODE
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.