Playstation SPDIF output

[Hojo_Norem]

Long story short, I've decided to try the mod linked to in this post .

Lets just say that so far I have had zero success, but at least I haven't killed my target machine yet ^_^

Essentially, the chip called for in the original mod (TC9231N, a Toshiba part) is pretty much impossible for me to get hold of, so I have been attempting to get it to work with the much more easily available Cirrus Logic CS8406.  After much fumbling with Google and various datasheets* I discover that the CS8406 can't do the required clock divider mode for the PSX's audio data.... while in hardware control mode (IE, the easy way to use the chip).  In software control mode there is the ability to set the correct divider but requires the use of a microcontroller communicating to the CS8406 via SPI or I2C, which is far beyond my current abilities.

So back to Farnell I went cause Toshiba and Cirrus Logic can't be the only ones making these chips, and I was correct as Texas Instruments also make a chip which, wait for it, has  the ability to set the correct mode by hardware.  The only down side is that Farnell have a £30 minimum order for 'normal people' and its a TSSOP part meaning harder to solder.

So onto eBay I go... One seller in the US was selling the chip for nearly £9 shipped while somebody a little more local was selling a TSSOP to dip converter PCB for little under a fiver.  When these arrive I'll give them a go and I'll let you folks know the result.


*Funnily enough the sheet for the TC9231N would have probably saved me a full night's wasted effort, but couldn't be found anywhere...

[viletim]

So back to Farnell I went cause Toshiba and Cirrus Logic can't be the only ones making these chips, and I was correct as Texas Instruments also make a chip which, wait for it, has  the ability to set the correct mode by hardware.  The only down side is that Farnell have a £30 minimum order for 'normal people' and its a TSSOP part meaning harder to solder.

This is Farnell UK? Compare this to Farnell Australia who have a minumun order of £6 (equivalent) and that comes with free delivery by courier.

[Hojo_Norem]

This is Farnell UK? Compare this to Farnell Australia who have a minumun order of £6 (equivalent) and that comes with free delivery by courier.

Odd.  I can remember my first order with Farnell and when I tried to pay with my credit card it threw a fit at me and complained that I handn't met the minimum order.  Not I just went over the site again and again and couldn't find any mention of a minimum order amount for non trade account holders (IE, normal people).

But, the part is ~£4.20 on Farnell.co.uk and there's about the same in the handling charge, which brings the total very close to what I paid on eBay.

[Hojo_Norem]

Good news, the chip arrived today.  I got it soldered onto the DIP adapter pcb and then wired into my Playstaiton.  It worked first time!  And even better, I was able to recude the chip count down to just the encoder IC, which I think will also work for the Gamecube SPDIF mod.

I'm going to take a crash course in wiki editing and I'l have a go at adding the into to the wiki.

[Shou]

I've done the mod using the Toshiba chip but I am hearing some interference on some games (crackles/pops). Anyone have any ideas on what could be causing this?

[Hojo_Norem]

I got the same at first after I had closed everything back up.  Thinking it was a short I undid everything again and it worked spot on.  Couldn't see a short so I put it back together and it worked without problem.  Now I haven't used my PSX for a few months and when I turned it on, I got the same cracking and popping.  A quick tap of reset and its clear again.

Anyway, here's a pic of the mod and its wiring.  Sorry for the slightly blurry shot ^_^

EDIT:  Heres a little more detailed info for those who have asked for it. (Wall o' text warning!)

The IC I used was the Texas Instruments  DIT4096.  I did a search on eBay for "TSSOP adapter" and I found a local seller selling the needed 28 pin TSSOP to DIP adapter PCB.  The PCB I used has a big ground pad underneath the IC so I cut the trace to make it into 2 pads and used them as convenient places to solder GND and VCC to.

The solder points on the PSX pcb were derived from looking at the specs for the original mod and tracing the relevant IC pins back to the closest VIAs (for slightly easier soldering).  I did solder one extra wire and that was for the DIT4096's reset line and that was soldered to the AK4309's reset line (thats the DAC in the PSX).

Now the hard part.  Like I mentioned in an earlier post, (for me) finding information on the Toshiba part was impossible and my exploits with the Cirrus Logic part were not bearing anything audible.  Luckily I was able to find the datasheet for the DAC (the aforementioned AK4309).  Now this is where the detective's hat went on...


First of all the Gamecube mod uses the same chip as the PSX one (even a similar arrangement for the supporting IC) and the instructions for that mod (unlike the ones for the PSX) had labelled the pins on the main IC so deciphering where to solder the pins on the TI part was relatively easy (watch out, some pins on the Toshiba are active high while they are active low on the CL and TI parts).  The hard part however was how to configure the TI chip as there was no info on the Toshiba chip I couldn't work out the correct settings.  Then it hit me... the DAC!  A quick google for the part revealed the datasheet and in that was the info I needed.  The DAC has few configuration pins and out of sheer luck the one value I couldn't work out (the MCLK frequency) was one of those settings and a quick probe about with the multimeter soon gave the answer (384 • fS by the way, which can't be selected on the CS part in hardware config mode, but can on the TI part).

I don't know why (I'm no electronics expert) but the TI chip (and I guess the CL chip too) don't need the extra glue logic IC that the toshiba part requires.

After that it was just a simple case of soldering it all in and powering it on... it worked first time!

[psyko_chewbacca]

What revision is your PSX? I have a SCPH-7501 and I don't have AK4309A(or B depending on the PSX) chip... I think that the whole audio data decoding is done internally by the DSP (part number CXD2938D) as it seems to be taking data on the main databus as the service manual suggest(http://psxdev.narod.ru/download/sony_playstation_scph-7500_service_manual_202.pdf).

I did probe LRC0, BCK0 and DTI0 lines and found in order 43KHz clock, 2.81MHz clock and a 3.3V average with a slight jitter but nothing to indicate activity on DTI0. This would make sense because this is an input signal from the Parallel port. The two others (LRC0 and BCK0) are bi-directionnal with the parallel port.

Does anyone know a place on the SCPH-7501 (PU-22) motherboard that does have the audio data stream traveling?

[Hojo_Norem]

My unit is aSCPH-5552.  I also have a 9000 series that is in the same boat as yours.

[psyko_chewbacca]

My unit is aSCPH-5552.  I also have a 9000 series that is in the same boat as yours.

Is the 5552 modable?