W83627DHG Datasheet, PDF (170/268 Pages) Winbond – WINBOND LPC I/O

W83627DHG
12.3.12.3. Data Compression
The W83627DHG hardware supports RLE decompression and can transfer compressed data to a
peripheral. Odd (RLE) compression is not supported in the hardware, however. In order to transfer data
in ECP mode, the compression count is written to ecpAFifo and the data byte is written to ecpDFifo.
12.3.13 FIFO Operation
The FIFO threshold is set in LD0 CRO0, bit 6 ~ 3. All data transferred to or from the parallel port can
proceed in DMA or Programmed I/O (non-DMA) mode, as indicated by the selected mode. The FIFO is
used in Parallel Port FIFO mode or ECP Parallel Port Mode. After a reset, the FIFO is disabled.
12.3.14 DMA Transfers
DMA transfers are always to or from the ecpDFifo, tFifo, or CFifo. DMA uses the standard PC DMA
services. The ECP requests DMA transfers from the host by activating the PDRQ pin. The DMA
empties or fills the FIFO using the appropriate direction and mode. When the terminal count in the DMA
controller is reached, an interrupt is generated, and serviceIntr is asserted, which will disable the DMA.
12.3.15 Programmed I/O (NON-DMA) Mode
The ECP and parallel port FIFOs can also be operated using interrupt-driven, programmed I/O.
Programmed I/O transfers are
1. To the ecpDFifo at 400h and ecpAFifo at 000h
2. From the ecpDFifo located at 400h
3. To / from the tFifo at 400h.
The host must set dmaEn and serviceIntr to 0 and also must set the direction and state accordingly in
the programmed I/O transfers.
The ECP requests programmed I/O transfers from the host by activating the IRQ pin. The programmed
I/O empties or fills the FIFO using the appropriate direction and mode.
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Publication Release Date: Aug, 22, 2007
Version 1.4