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S/PDIF Output on Asus K8S-LA “Salmon”

fwaggle — Sun, 07 Mar 2010 19:46:09 +0000

Ever since I got a PlayStation 2 and found the joy of games that support Pro Logic II, I’ve had a thing for surround sound. It’s like this perverse fixation that gives me a boner every time – you haven’t played games like Need for Speed: Underground 2 or Ace Combat 5 until you’ve played them with Pro Logic II. Seriously, the effect is that dramatic.

The PS3 is even better because most games support Dolby Digital 5.1 native – the PS2 lacked the processing power to generate this signal dynamically, only pre-rendered cut-scenes had Dolby Digital.

I started out modest – an old “Paramount” Pro Logic decoder, which I eventually traded in for a Yamaha 5.1 receiver. This thing is great – it’ll fill up a huge room with modest speakers no trouble at all, and it’s been in our “great room” since we moved out here. Unfortunately, our “nice TV” broke permanently, and we shut off our satellite TV in favor of streaming NetFlix… meaning my beautiful receiver was relegated to my younger brothers in law playing PS2 on it.

This morning I decided enough of that, I’d bring it up here and use it in our bedroom. Story time over: I decided to see if I could hack digital output from my HP Pavilion a1213w desktop. I checked the motherboard, it’s an Asus K8S-LA “Salmon” board… bit of a piece of shit really, but it does the job.

It sports a RealTek (ugh!) on-board audio with 5.1 output. Awesome – but no digital output in sight. Searching for the manual, I found an S/PDIF output on the board which requires a daughter-board to give you a coaxial/ToSLink output. Check eBay – ~$20… fffffuuuuuu that.

A quick Google search shows plenty of other folks hacking their own so I decided to give it a shot. Ratting through my box of parts, I came up with a 4-pin CD-ROM-Audio cable from years gone past and cut it apart. I also dug out an RCA cable (I went with Coaxial for the PC since my PS3 will be using the only available ToSLink socket on the receiver) and cut it up too.

A simple hack really. Pins 1+2 are ground and digital-out respectively, with the third pin being +5vdc for powering the bits for ToSLink communication… irrelevant for my purposes. I carefully cut the connector to a little larger than the three-pin connector, then used a Dremel with a sanding wheel to smooth it to a perfect three-pin shape. I pulled the unused extra wire out, since I didn’t want to accidentally short my mobo’s +5vdc. I had the black wire on the GND pin and the white on the S/PDIF pin (see diagram at left) and it was a simple matter of soldering colors to colors to connect the RCA. Route it out the back of my PC and into my receiver.

Digging through the RealTek control panel’s “Multi-Channel Sound Manager”, the instant I clicked “Enable Digital Output” the PCM light came on my receiver and I’m good to go. Turn off all the DSP shit the kids had turned on, and my iTunes output is so manly I need chest hair supplements to keep up.

Update: Okay so apparently my RealTek card can’t output Dolby Pro Logic II (or even anything remotely close to surround sound) over S/PDIF – PCM is it (and PCM is limited to two channels). According to a thread on Overclockers, most sound cards are limited like this… if you want surround sound in games, you’re stuck using the analog outputs and the 6ch input on my receiver.

So I scrounged up some 3.5mm to RCA cables, and hooked it up… and low and behold I have full surround on games like Left4Dead. I press the 6ch button on my remote, and I’m switching back to digital output, so I can take advantage of my receiver’s vastly superior DAC for music. Not optimal, but the best I can probably do without a heinously expensive Pro Logic II capable sound card.

Howto: JTAG interface on a Dish 3700 Receiver

fwaggle — Sun, 05 Aug 2007 17:55:17 +0000

I picked up this receiver in a box of stuff at a yard sale for $2. We have DirecTV service here, so I was left wondering what the hell I could do with such an archaic device. A quick search shows up that apparently I can’t get the card activated any more. From dabbling with various embedded environments, I was familiar with a JTAG interface and I learned that this box indeed has one.

So what can we do with this? I’m led to believe that Dish hackers use this interface to take a snapshot of the firmware on the dish and replace parts of it as they need to. We’ll go into no such nonsense – under fear of the DMCA – however I don’t believe that discussion of or probing the JTAG interface falls under such legislation, unless I receive a letter from a company involved. So here we go:

You will need:

5 100ohm resistors, at least 1/4 watt.
Category 5, or some other kind of signal cable
A female DB-25 connector
Some software to read the JTAG interface on the parallel port

You will also obviously need a soldering iron and some proficiency in using it. We’re not dealing with any SMT devices or anything here, the pin holes are quite large and should pose little difficulty for anyone that’s ever soldered anything before in their life. You will want your cable long enough to reach from the box to the back of your PC. In my case, I simply chickened out and cut up a printer cable, but OrganizedChaos used Cat5 with success.

It became obvious that I would have been able to access the JTAG port from outside the case, without even opening it – I assume this is so that Dish can test and possibly program the boxes before they leave the factory. The JTAG pins are pins 184-190 on the CPU (as can be referenced from the datasheet found at Datasheet Archive). The traces are absolutely tiny, so it takes some serious time to follow them to the correct pads – an ohmeter with tiny probes speeds things up considerably.

In our case, we won’t be powering the JTAG interface – we’ll simply plug the unit in, leave it off, and let the standby power supply the juice necessary for our probing. I imagine this would be much more reliable than trying to supply 3.3v from our parallel port.

The first thing I did was source 5 100ohm resistors. I managed to find two in an ATX power supply, and another four off the board of a television set. I needed the extra one because I broke one swinging it around on the PCB. I straightened the legs out, and soldered one resistor into each of the pads that require them.

In the diagram below, I’m labeling each of the pins going down in two pairs from what I’m assuming is the “#1 pin” (the one closest to the angle that’s been chopped off the box on the PBC). This pin layout is not the standard 20-pin JTAG! I was probably pretty lucky I traced the tracks and didn’t just assume it was standard, because I’m sure I’d either have killed my printer port or the dish box (the former being the bigger deal) if I’d just blindly hooked it up. By the way, if you check out the full-size photo to the right, the pins are highlighted in mouseover notes for your information.

N/C DB25 N/C DB24 N/C DB23 N/C DB22 DB02 DB21 DB03 DB20 DB04 DB19 DB13 N/C N/C N/C DB05 N/C

You will notice that pins 19-25 are connected to the grounded pins on the JTAG interface – this probably isn’t necessary, one would probably suffice (I’m pretty sure pins 18-25 are all connected at your PC’s parallel port), I just got frisky with the soldering iron. Pins 2, 3, 4, 5 and 13 are where the action is, so you’ll want to make sure the connections through the resistors are pretty good. OC put his resistors on the DB25 connector, I put mine on the board, either way… doesn’t matter.

Once everything’s soldered up, plug the DB25 cable into your PC, then plug the box in but don’t turn it on. You’ll need some software – after googling around I found some software called jKeys which seems to work pretty good. I should point out that it’s often used for theft of service and I’d really rather steer clear of that on this website – do not email me about trying to steal Dish Network TV.

Once you point your software at the parallel port, you should be able to find out all kinds of nifty information about the device. I’m led to believe JTAG supports in-circuit debugging… we’re actually toying with the idea of playing around with a Dish x700 “hello world” application, because looking at the datasheets for the STi5500 CPU the OSD modules seem pretty trivial to operate.

But for now, we can experiment with all kinds of neat functions that JTAG allows. Happy hacking!

Update: 2007-08-11

I’ve gone ahead and hosted Jkeys anyway, but I want to make it clear that I don’t support theft of service. The reason I’ve included it is because I haven’t yet found another (free) way of programming the flash after you build something using the STi5500 toolkit. So far I’ve not yet managed to even so much as get the LED to flash, but I did manage to resurrect the box after I thought I’d bricked it.

I’m also including a nifty program called JTango. It’s a JTAG program again, but it’s used for in-circuit debugging. At least, that’s what I gather, I couldn’t make it work with Windows XP. I’ve included the driver that’s allegedly supposed to fix the “Privileged Instruction” error, but it didn’t work for me. If you figure it out, please do let me know.

Now it’s time to hit up more documentation and see if I can at least make the freakin’ box flash it’s LED or something… at least something to tell me it’s working.

Fixing a broken USB Graphics Tablet

fwaggle — Wed, 04 Jul 2007 11:01:29 +0000

I picked up my Jam Studio graphics tablet a good few years back for the price of $10. Make no mistake about it, these are a low-priced budget tablet, and they perform about that too. Anyway, a while ago our pet rats got a hold of the cord, and chewed it in two pieces. I threw away the end, but I tossed the tablet into a box and kept it for a few years and I finally dug it out yesterday.

I tore it apart, and soon realized that there was way too many wires, and none of them were standard color codes. This is because it has a weird dongle that you can attach a DB-9 serial plug onto instead of a USB. Next I noticed the Cypress Semiconductor USB controller sitting on the board. I managed to track down the data sheet to it, and enumerate which pins were which. Tracing these back to the cable I get:

Pin	USB Wire	Original Wire	Function
E13	Black	Black	Ground
E16	Green	Orange	Data +
E18	White	Green	Data -
E21	Red	Lt Grey	+5VDC

If you want, you can tie E17 to the shield – or E17 to USB black, and E13 to the shield of the USB cable (the original cable is unshielded however).

Installing the Drivers on Windows XP

This part sucks – it’s not very intuitive at all. I’ve found it easiest to install the driver prior to plugging in the tablet, otherwise you have to do some juggling to get it to ever function. Instructions:

Download jamstudio-tablet-win95-98-me-2000-xp.zip and extract it to a folder someplace. This mightn’t be necessary, but I did it anyway so I could burn the driver to a CD just in case.
Run setup.exe from inside the driver folder, and follow the instructions. This will install the driver (but not attach it to the hardware in Windows XP) and the control panel applet.
Plug your tablet in. Windows XP will detect the tablet, but it won’t function yet.
Under Device Manager (Right-click on My Computer, choose properties, Hardware tab, then choose Device Manager), look for the two devices that represent the tablet. They should be something like USB Human Interface Device and HID-compliant device. Open up HID-compliant device.
Under the Driver tab, choose Update Driver. Tell it you want to select the driver yourself, and eventually you’ll convince Windows you really do want to select the driver yourself. By this time, it should pop up the list of similar devices, one of which should be KBGear Jam Studio Digitizer. Select it, then dismiss all dialogs.
On both my computers, the digitizer now worked for positioning but didn’t reckognize mouse clicks from the pen touch. If your’s does this too, simply open the control panel applet and toggle the settings to heavier then back to light. Experiment with these settings.

So there you have it. A cheap ass tablet, salvaged thanks to the fact that the semiconductor company who made it’s controller saw fit to put the information on the Internet for all to see.