6.7.4 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.
6.7.5 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
D6
D5
D4
D3
D2
D1
D0
Note
data
PD7
PD6
PD5
PD4
PD3
PD2
PD1
PD0
ecpAFifo Addr/RLE
Address or RLE field
Select nFault
2
1
1
2
2
2
dsr
nBusy
0
nAck
0
PError
0
0
0
dcr
Direction ackIntEn SelectIn
Parallel Port Data FIFO
ECP Data FIFO
nInit
autofd
strobe
cFifo
ecpDFifo
tFifo
Test FIFO
cnfgA
cnfgB
ecr
0
0
0
1
0
0
0
0
compress intrValue
MODE
Parallel Port IRQ
Parallel Port DMA
full empty
nErrIntrEn dmaEn serviceIntr
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 DRQ selected by the Configuration Registers.
6.7.6 ECP IMPLEMENTATION STANDARD
This specification describes the standard interface to the Extended Capabilities Port (ECP). All LPC devices supporting
ECP must meet the requirements contained in this section or the port will not be supported by Microsoft. For a
description of the ECP Protocol, please refer to the IEEE 1284 Extended Capabilities Port Protocol and ISA Interface
Standard, Rev. 1.14, July 14, 1993. This document is available from Microsoft.
Description
SMSC DS – LPC47S45x
Page 83 of 259
Rev. 07/09/2001
DATASHEET
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