Hi all
I have been working on a project just like this. I want to use the 3-wire audio output that the CD-ROM has for its internal DAC, and connect it to a better DAC chip. So I took my CD-ROM apart and checked it out.
This was a BTC 24x CD-ROM. The controller chip was a SAA7348 made by Philips. I found out that the feed to the onboard DAC is 4x oversampled using a digital filter built into the controller chip.
Does anyone have any thoughts on the quality of this digital filter? I think it might not be too good. I found out that the SAA7348 chip can be reprogrammed to disable the oversampling and output plain I2S data. This might not be too difficult as the chip is 8051 compatible and it seems to run off an external ROM chip.
The controller chip does have an S/PDIF output but I would rather not use it because of the dreaded jitter
Also does anyone know if other CD-ROMs use this Philips IC?
I have been working on a project just like this. I want to use the 3-wire audio output that the CD-ROM has for its internal DAC, and connect it to a better DAC chip. So I took my CD-ROM apart and checked it out.
This was a BTC 24x CD-ROM. The controller chip was a SAA7348 made by Philips. I found out that the feed to the onboard DAC is 4x oversampled using a digital filter built into the controller chip.
Does anyone have any thoughts on the quality of this digital filter? I think it might not be too good. I found out that the SAA7348 chip can be reprogrammed to disable the oversampling and output plain I2S data. This might not be too difficult as the chip is 8051 compatible and it seems to run off an external ROM chip.
The controller chip does have an S/PDIF output but I would rather not use it because of the dreaded jitter
Also does anyone know if other CD-ROMs use this Philips IC?
Watch out this link:
http://www.rockna-line.com/diy.htm
Very soon all the sections will be available, including cd-rom controller.
I'll send a note when ready...
http://www.rockna-line.com/diy.htm
Very soon all the sections will be available, including cd-rom controller.
I'll send a note when ready...
I don't know, since I've never used any of the free programmers with either flavour of 16F877. But I have noticed that the A parts burn faster on the MPLAB ICD 2 at work. So I suppose they do use different burning routines.
Anyway, Farnell also sell the non-A part. I just looked on www.farnell.com and it's listed as part # 324-5573.
Anyway, Farnell also sell the non-A part. I just looked on www.farnell.com and it's listed as part # 324-5573.
CurrentFeedback said:You can get them mail order from Farnell.
The PIC part numbers are quite confusing, I have seen chips labelled PIC16F877-04 that run happily at 20MHzThe part I buy now is the PIC16F877A-I/P, which is definitely 20Mhz, and cost about 7 GBP.
im might order some samples of these, as microchip stock them, but not the non-A version.
CurrentFeedback said:
i'll have a look at farnell then.
Anybody interested for finished Kit.
Hello,
From this thread inspire me to start this project from zero knowledge about micro controller. I start this since beginning of DEC 2003.
Right now nearly finished. My prototype can connect to CDROM
use structure from Mucop (Have some BUG but also thank him Mucop). I finished to display on LCD. I suppose this next 2 week
will finished Remote Control.
All of this is my hobby done after work.
I intend to sell this finished Kit 45 USD.(for finished Kit+remote+Lcd) but not include shipping charge, shipping will charge costly.
Approximately shipping charge to USA, Europe, Australia 30 USD.
Asian country 20 USD.
If anybody interest this kit mail me.
pradit@neonmagazine.com
next 2 week I will post finished one and also post in Trading Post.
Hello,
From this thread inspire me to start this project from zero knowledge about micro controller. I start this since beginning of DEC 2003.
Right now nearly finished. My prototype can connect to CDROM
use structure from Mucop (Have some BUG but also thank him Mucop). I finished to display on LCD. I suppose this next 2 week
will finished Remote Control.
All of this is my hobby done after work.
I intend to sell this finished Kit 45 USD.(for finished Kit+remote+Lcd) but not include shipping charge, shipping will charge costly.
Approximately shipping charge to USA, Europe, Australia 30 USD.
Asian country 20 USD.
If anybody interest this kit mail me.
pradit@neonmagazine.com
next 2 week I will post finished one and also post in Trading Post.
I love this thread and the awesome projects. I'm just not understanding something here, please help me out.
"Jitter" is what exactly? Does this cause the breakup of sound? I have been playing with a DIT4096 circuit, for converting 24 bit i2s audio into S/PDIF. It's used to give S/PDIF output to almost any XM receiver, because of the 3 clock lines and a data line from the XM service layer decoder. The service layer decoder also has S/PDIF output, on pin 78, but seems to be turned on by a register. To my knowledge, all receivers containing the metal enclosure have the register turned off, also the Sony DRN-XM01MK2. This circuit using the DIT4096 is usefull for these receivers. When testing it on a Pioneer GEX-FM903XM, I got noise, sounding like static, and break up of the audio. Does jitter cause this?
I have a pioneer DVR-A04 in my PC, connected to my sound blaster audigy via TTL S/PDIF, and It sounds fine. No breakup or anything really.
I have some older drives too. For this reason I'm just concerned about a project that will control the drive, and I'll use the S/PDIF output. With a clean power supply, how can the S/PDIF output be that bad? Now I'm sure crappy drives will sound worse, but i plan on using an old NEC drive I have if it has S/PDIF output.
"Jitter" is what exactly? Does this cause the breakup of sound? I have been playing with a DIT4096 circuit, for converting 24 bit i2s audio into S/PDIF. It's used to give S/PDIF output to almost any XM receiver, because of the 3 clock lines and a data line from the XM service layer decoder. The service layer decoder also has S/PDIF output, on pin 78, but seems to be turned on by a register. To my knowledge, all receivers containing the metal enclosure have the register turned off, also the Sony DRN-XM01MK2. This circuit using the DIT4096 is usefull for these receivers. When testing it on a Pioneer GEX-FM903XM, I got noise, sounding like static, and break up of the audio. Does jitter cause this?
I have a pioneer DVR-A04 in my PC, connected to my sound blaster audigy via TTL S/PDIF, and It sounds fine. No breakup or anything really.
I have some older drives too. For this reason I'm just concerned about a project that will control the drive, and I'll use the S/PDIF output. With a clean power supply, how can the S/PDIF output be that bad? Now I'm sure crappy drives will sound worse, but i plan on using an old NEC drive I have if it has S/PDIF output.
Jitter is not something that you just hear and say oh yeh thats jitter. You cant 'hear' the jitter. It affects the accuracy of the cd player at a base level. It primarily affects (in my experience) the imaging ability of a system. Jitter is not something you should worry about if you have an Audigy card which upsamples cd to 48khz before decoding.