Creative SB0350 Hardware Programming Guide - Page 43
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3-14 Digitized Sound I/O Programming When the DSP sends an interrupt, the following steps should be done in the interrupt service routine: 1. 2. Program the DMA controller for the next block. Program the DSP for the next block. outp(wSBCBaseAddx+0xC, bCommand) outp(wSBCBaseAddx+0xC, wLength.LowByte) outp(wSBCBaseAddx+0xC, wLength.HighByte) bCommand is one of the following: bCommand 24h 14h 74h 76h 16h Description 8-bit PCM input 8-bit PCM output 8 bit to 4 bit ADPCM output without reference byte 8 bit to 3 bit ADPCM output without reference byte 8 bit to 2 bit ADPCM output without reference byte Please note that for ADPCM output, subsequent data block transfers must be programmed using different commands; specifically those that do not take a reference byte. At the end of data transfer: 1. 2. 3. Turn off the DAC speaker. outp(wSBCBaseAddx+0xC, 0xD3) Disable the interrupt used. Restore the original interrupt service routine.