av:dreamcastda
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+ | ==== Adding Digital Audio to the Sega Dreamcast ==== | ||
+ | And on the heels of the Saturn digital audio mod here's one for the dreamcast. | ||
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+ | The dreamcast generates digital audio internally and then passes it to a digital analog converter chip. As it uses an off the shelf d/a converter (PCM1725U) it's possible to interface the digital audio signals to an S/PDIF transmitter IC that will transform the digital audio into a form your amplifier will understand. | ||
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+ | Here are the hookups for the Cirrus CS8406 chip I used here. | ||
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+ | {{av: | ||
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+ | ^ Signal | ||
+ | | EMPH: emphasis - See Note!! | 3 | 12 | | ||
+ | | ILRCK: Word Clock | 12 | 1 | | ||
+ | | ISCLK: Bit Clock | 13 | 3 | | ||
+ | | SDIN: Audio Data | 14 | 2 | | ||
+ | | OMCK: Master Clock | 21 | 14 | | ||
+ | | GND | | 7 | | ||
+ | | +5v | | 8 | | ||
+ | | TXP: S/Pdif output | ||
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+ | You can hook up a toslink transmitter directly or wire up a coax connector with the same circuit as in the SNES mod. | ||
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+ | {{av: | ||
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+ | ===Note=== | ||
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+ | I looked at the data sheets again. The EMPH line on the cirrus chip is high for no pre-emphasis. Pin 12 on the PCM1725U is high for de-emphasis active. Therefore the signal should be inverted. | ||
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+ | === Construction === | ||
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+ | My first mod using the CS8406 was adding digital audio to the saturn. I wired everything directly to the chip. It worked but was a rather nerve wracking experience. | ||
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+ | {{av: | ||
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+ | This time I used a soic to dip adaptor board and the soldering was a lot easier. The board adds a bit to the cost but it's worth it. You can't see it in the pic, but there is a small capacitor between +5V and Ground. The chip works without it but it seemed a good idea. | ||
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+ | A few notes on installation: | ||
+ | I soldered the +5v and GND leads to CF302 rather than the chip as access is a bit easier. When placing the toslink optical transmitter or RCA jack make sure you do a dry run and put the board in the case with the top and bottom rf shields in place. For instance I put the RCA jack around the corner from the expansion port and found that I needed to put the top shield in place before I soldered the orange TXP wire to the RCA jack. | ||
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+ | == Where to find the parts == | ||
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+ | CS8406 soic package: [[http:// | ||
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+ | SOIC to DIP adaptor board: | ||
+ | [[http:// |