SP37E760 Datasheet, PDF (33/78 Pages) SMSC Corporation – 3.3 V I/O CONTROLLER FOR EMBEDDED APPLICATIONS

5.4 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
5.4.1 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 ISA interface. For this implementation, PWord is always 8
bits.
1
A high level
0
A low level
These terms may be considered synonymous:
ƒ PeriphClk, nAck
ƒ HostAck, nAutoFd
ƒ PeriphAck, Busy
ƒ nPeriphRequest, nFault
ƒ nReverseRequest, nInit
ƒ nAckReverse, PError
ƒ Xflag, Select
ƒ ECPMode, nSelectln
ƒ HostClk, nStrobe
Reference Document:
IEEE 1284 Extended Capabilities Port Protocol and ISA Interface Standard, Rev 1.09, Jan 7, 1993. This document is
available from Microsoft. The bit map of the Extended Parallel Port registers is shown in Table 16.
Note¹
Note²
data
ecpAFifo²
dsr¹
dcr¹
cFifo²
ecpDFifo²
tFifo²
cnfgA
cnfgB
ecr
D7
PD7
Addr/RLE
nBusy
0
Table 16 - ECP Registers
D6
D5
D4
D3
D2
PD6
PD5
PD4
PD3
PD2
Address or RLE field
nAck
PError
Select
nFault
0
0
Direction ackIntEn SelectIn
nInit
0
compress
0
intrValue
MODE
Parallel Port Data FIFO
ECP Data FIFO
Test FIFO
0
1
0
0
0
0
nErrIntrEn dmaEn
0
0
serviceIntr
These registers are available in all modes.
All FIFOs use one common 16 byte FIFO.
D1
PD1
0
autofd
0
0
full
D0
PD0
0
strob
e
0
0
empt
y
SMSC DS – SP37E760
Rev. 04/13/2001