Creative SB0350 Hardware Programming Guide - Page 51

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3-22 Digitized Sound I/O Programming 8. Set the DSP block transfer size. outp(wSBCBaseAddx+0xC, 0x48) outp(wSBCBaseAddx+0xC, wBlkSize.LowByte) outp(wSBCBaseAddx+0xC, wBlkSize.HighByte) wBlkSize is one less than the actual transfer size. 9. Send an I/O command to start high-speed single-cycle DMA mode transfer. outp(wSBCBaseAddx+0xC, bCommand) bCommand is one of the following: bCommand 99h 91h Description 8-bit PCM high-speed input 8-bit PCM high-speed output Upon receiving an interrupt from the DSP, the following steps should be done in the interrupt service routine: 1. 2. Program the DMA controller for subsequent block. Set the DSP block size and program the DSP for the next block. At the end of data transfer: 1. Restore the filter status. a. b. For stereo input: outp(wSBCBaseAddx+0x4, 0xC) outp(wSBCBaseAddx+0x5, bInputFilter) For stereo output: outp(wSBCBaseAddx+0x4, 0xE) outp(wSBCBaseAddx+0x5, bOutputFilter) 2. Set the hardware to mono mode. a. b. For stereo input: outp(wSBCBaseAddx+0xC, 0xA0) For stereo output: outp(wSBCBaseAddx+0x4, 0xE) bTmp = inp(wSBCBaseAddx+0x5) outp(wSBCBaseAddx+0x5, (bTmp & 0xFD)) 3. 4. 5. Turn off the DAC speaker. outp(wSBCBaseAddx+0xC, 0xD3) Disable the interrupt used. Restore the original interrupt service routine. During high-speed DMA mode data I/O, the DSP will not accept any commands. Hence, to stop data transfer before the end of a block, send the reset DSP command.

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3-22
Digitized Sound I/O Programming
8.
Set the DSP block transfer size.
outp(wSBCBaseAddx+0xC, 0x48)
outp(wSBCBaseAddx+0xC, wBlkSize.LowByte)
outp(wSBCBaseAddx+0xC, wBlkSize.HighByte)
wBlkSize
is one less than the actual transfer size.
9.
Send an I/O command to start high-speed single-cycle DMA mode
transfer.
outp(wSBCBaseAddx+0xC, bCommand)
bCommand
is one of the following:
bCommand
Description
99h
8-bit PCM high-speed input
91h
8-bit PCM high-speed output
Upon receiving an interrupt from the DSP, the following steps should be done in the
interrupt service routine:
1.
Program the DMA controller for subsequent block.
2.
Set the DSP block size and program the DSP for the next block.
At the end of data transfer:
1.
Restore the filter status.
a.
For stereo input:
outp(wSBCBaseAddx+0x4, 0xC)
outp(wSBCBaseAddx+0x5, bInputFilter)
b.
For stereo output:
outp(wSBCBaseAddx+0x4, 0xE)
outp(wSBCBaseAddx+0x5, bOutputFilter)
2.
Set the hardware to mono mode.
a.
For stereo input:
outp(wSBCBaseAddx+0xC, 0xA0)
b.
For stereo output:
outp(wSBCBaseAddx+0x4, 0xE)
bTmp = inp(wSBCBaseAddx+0x5)
outp(wSBCBaseAddx+0x5, (bTmp & 0xFD))
3.
Turn off the DAC speaker.
outp(wSBCBaseAddx+0xC, 0xD3)
4.
Disable the interrupt used.
5.
Restore the original interrupt service routine.
During high-speed DMA mode data I/O, the DSP will not accept any commands.
Hence, to stop data transfer before the end of a block, send the
reset DSP
command.