LPC47M182 datasheet(110/223 Pages) SMSC

110 / 223 page

Advanced I/O Controller with Motherboard GLUE Logic

Datasheet

Revision 1.8 SMSC/Non-SMSC Register Sets (02-24-05)

110

SMSC LPC47M182

DATASHEET

Table 7.8 – Programming for Configuration Register B (Bits 2:0)

DMA SELECTED

CONFIG REG B

BITS 2:0

011

010

001

All Others

000

7.13

Operation

7.13.1 Mode Switching/Software Control

Software will execute P1284 negotiation and all operation prior to a data transfer phase under

programmed I/O control (mode 000 or 001). Hardware provides an automatic control line handshake,

moving data between the FIFO and the ECP port only in the data transfer phase (modes 011 or 010).

Setting the mode to 011 or 010 will cause the hardware to initiate data transfer.

If the port is in mode 000 or 001 it may switch to any other mode. If the port is not in mode 000 or 001 it

can only be switched into mode 000 or 001. The direction can only be changed in mode 001.

Once in an extended forward mode the software should wait for the FIFO to be empty before switching

back to mode 000 or 001. In this case all control signals will be deasserted before the mode switch. In an

ecp reverse mode the software waits for all the data to be read from the FIFO before changing back to

mode 000 or 001. Since the automatic hardware ecp reverse handshake only cares about the state of

the FIFO it may have acquired extra data which will be discarded. It may in fact be in the middle of a

transfer when the mode is changed back to 000 or 001. In this case the port will deassert nAutoFd

independent of the state of the transfer. The design shall not cause glitches on the handshake signals if

the software meets the constraints above.

7.14

ECP Operation

Prior to ECP operation the Host must negotiate on the parallel port to determine if the peripheral supports

the ECP protocol. This is a somewhat complex negotiation carried out under program control in mode

000.

After negotiation, it is necessary to initialize some of the port bits. The following are required:

Set Direction = 0, enabling the drivers.

Set strobe = 0, causing the nStrobe signal to default to the deasserted state.

Set autoFd = 0, causing the nAutoFd signal to default to the deasserted state.

Set mode = 011 (ECP Mode)

ECP address/RLE bytes or data bytes may be sent automatically by writing the ecpAFifo or ecpDFifo

respectively.

LPC47M182 Datasheet(PDF) 110 Page - SMSC Corporation

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