[dvw]

It is not my intention to discredit any manufacturer. But here's a little known fact. Semiconductor companies in their quest for faster time to market has produced reference designs that include PC board, software and sometimes even FCC certification. The intention is for the customers to have a cookie cutter design block that manufacturers can add value to and I'm sure some of them do add their value.
 
Here's an example. http://www.xmos.com/products/reference-designs 
 
This is an USB DAC design. It has all the hardware and test points needed. It can also perform USB to SPDIF conversion in addition to being a functional DAC. As with all reference design, performance is published. The jitter performance is 4.6ps. This board can be purchased from Digikey for $149. Ah, it is also in two layer board in the size of a credit card. XMOS target customer are industrial application like Pro audio. So their chip is embedded with a 500MIPs 6 core processor. In most consumer application this is an overkill. In theory, you can purchase this, put in your enclosure and sell it as an audiophile product and charge $300.
 
I do not recommend anyone buying this product because it is not consumer friendly and it may or may not even come with an enclosure. In addition, you have to load the firmware before it works. None the less, the point I'm trying to make is it seems like USB audio is complex but it is not. And there are many way to add value but there is very little value to add at the media (USB) side. Even at the play clock, how much can you improve with 4.6ps. Maybe at $1,000, the jitter should be 0.5ps?

 

[proton007]

Quote:

It is not my intention to discredit any manufacturer. But here's a little known fact. Semiconductor companies in their quest for faster time to market has produced reference designs that include PC board, software and sometimes even FCC certification. The intention is for the customers to have a cookie cutter design block that manufacturers can add value to and I'm sure some of them do add their value.
 
Here's an example. http://www.xmos.com/products/reference-designs
 
This is an USB DAC design. It has all the hardware and test points needed. It can also perform USB to SPDIF conversion in addition to being a functional DAC. As with all reference design, performance is published. The jitter performance is 4.6ps. This board can be purchased from Digikey for $149. Ah, it is also in two layer board in the size of a credit card. XMOS target customer are industrial application like Pro audio. So their chip is embedded with a 500MIPs 6 core processor. In most consumer application this is an overkill. In theory, you can purchase this, put in your enclosure and sell it as an audiophile product and charge $300.
 
I do not recommend anyone buying this product because it is not consumer friendly and it may or may not even come with an enclosure. In addition, you have to load the firmware before it works. None the less, the point I'm trying to make is it seems like USB audio is complex but it is not. And there are many way to add value but there is very little value to add at the media (USB) side. Even at the play clock, how much can you improve with 4.6ps. Maybe at $1,000, the jitter should be 0.5ps?

 
Thanks for the reference. According to their website some of their products already have USB Audio Class implementations, so they're plug and play as far as I can tell. No driver required.

 

[dvw]

You will need drivers if you use it in a PC. They're providing the Windows drivers. But if you use it as a stand alone you don't need driver only the firmware. The firmware do some house keeping chores and help synchronizing the clocks. From what I see it's not difficult to get. Looks like all you need is to register and maybe sign a software liceence agreement. But you will need to know how to load the firmware. From your post, looks like you might be able to do it by yourself. This would be an interesting DIY project.

 

[dvw]

Here's a pseudo-review.
 
http://www.fetaudio.com/archives/1440

 

[ab initio]

Quote:

Here's an example. http://www.xmos.com/products/reference-designs

Thanks for the great link. These are exactly the kind of gadgets I love getting my hands on.

 
Cheers

 

[dvw]

If you want to get one, make sure you get the right one. the manual that I have is XS1-L1. And here's the block diagram.
 

 
As you can see this board included CS4270 DAC and it's pretty much self contained. The only tweak you might want to do is to get a higher voltage supply for CS4270 to get a little more performance.

 

[proton007]

Quote:

You will need drivers if you use it in a PC. They're providing the Windows drivers. But if you use it as a stand alone you don't need driver only the firmware. The firmware do some house keeping chores and help synchronizing the clocks. From what I see it's not difficult to get. Looks like all you need is to register and maybe sign a software liceence agreement. But you will need to know how to load the firmware. From your post, looks like you might be able to do it by yourself. This would be an interesting DIY project.

 
Yes, unless using PCI, there's no need for a driver as long as the device has the USB implementation. On the Firmware side, a JTAG programmer is required. They provide the source code.

 

[dvw]

Quote:

 
Yes, unless using PCI, there's no need for a driver as long as the device has the USB implementation. Otherwise, I think a JTAG programmer is required. Most people who work on embedded systems will have one.

Yes you are right. However, this chip has a 500MIPS 6 core processor. It can do many more tasks than a simple USB DAC. It is really intended for embedded application. Most other USB DAC chips used 8051 only. Some examples; this chip will support up to 40 channels. You can use it in a PA system and use the processor to compensate for all the delay. Another application that someone over at Harmon told me is sound effect on some of the roller coaster ride (in Disneyland). They used thousands of them. In our little USB-DAC application, this is an obvious overkill unless you want to add things like equalizer, an Android app. But hey, it is comparatively cheap if you don't mind building your own enclosure. A nice wood enclosure would be very cool. Heck you might even be able to sell it for big buck.
 
BTW, all programming, debug, flash loading are done through JTAG as you said. That's why I said this is not a consumer ready product.

 

[proton007]

Quote:

Yes you are right. However, this chip has a 500MIPS 6 core processor. It can do many more tasks than a simple USB DAC. It is really intended for embedded application. Most other USB DAC chips used 8051 only. Some examples; this chip will support up to 40 channels. You can use it in a PA system and use the processor to compensate for all the delay. Another application that someone over at Harmon told me is sound effect on some of the roller coaster ride (in Disneyland). They used thousands of them. In our little USB-DAC application, this is an obvious overkill unless you want to add things like equalizer, an Android app. But hey, it is comparatively cheap if you don't mind building your own enclosure. A nice wood enclosure would be very cool. Heck you might even be able to sell it for big buck.
 
BTW, all programming, debug, flash loading are done through JTAG as you said. That's why I said this is not a consumer ready product.

 
Are you sure its a multicore? From the datasheet, it says its an event driven multithreaded single core processor, which will implement some sort of a state machine that transfers data to the audio codec. Also, it only has an OTP (One time programmable) for storing the firmware.
Hence, I doubt it can run an OS like android. Perhaps you're talking about some other Xmos offering?

 

[dvw]

Quote:

 
Are you sure its a multicore? From the datasheet, it says its an event driven multithreaded single core processor, which will implement some sort of a state machine that transfers data to the audio codec. Also, it only has an OTP (One time programmable) for storing the firmware.
Hence, I doubt it can run an OS like android. Perhaps you're talking about some other Xmos offering?

 
This is the page I am reading from. http://www.xmos.com/products/reference-designs/usb-audio 
Actually, it said 8 cores. Hmmm.. the manual I have said what you said. Then I went and look at their L-family product. Look like they have any where from 4 to 32 core. They might have different reference design boards. Or there might be a typo.

 

[dvw]

Man, the XMOS site is difficult to navigate. Any way, the part number goes by XS-Ln. n is the number of core. The part number in the manual is XS1-L1. However, if you go to the buy page, there is no XS1-L!. The smallest is a L4. But L4 does not come in 128PQFP. You need to get to L6 and L8 before you see 128PQFP. My speculation is the reference design was originally a L8. Because of popularity in this type of application, they reduce the price by downgrading it to a single core. It might also be possible that the firmware is already loaded since their only distributor is Digikey. Of course all these are just speculation, mumble jumbo.

 

[proton007]

Quote:

Man, the XMOS site is difficult to navigate. Any way, the part number goes by XS-Ln. n is the number of core. The part number in the manual is XS1-L1. However, if you go to the buy page, there is no XS1-L!. The smallest is a L4. But L4 does not come in 128PQFP. You need to get to L6 and L8 before you see 128PQFP. My speculation is the reference design was originally a L8. Because of popularity in this type of application, they reduce the price by downgrading it to a single core. It might also be possible that the firmware is already loaded since their only distributor is Digikey. Of course all these are just speculation, mumble jumbo.

 
Add to this the fact that they have a One Time Programmable memory. Unless there's a ROM somewhere (the schematics don't have any) you can't erase and re-flash the chip, so the firmware is most probably loaded in.

 

[dvw]

We're way off topic. But I don't think AB would mind. Any way I spent sometime researching this and seems like this is a very popular DIY. Many manufacturers used this chip including Arcam. Price ranged from $500 (barebone design, HRT) to $4,000 (tube).  Most swap the DAC replacing Cirrus with TI. DIYers also used it in conjunction with a TI PCM5102 evaluation module ($199).
 
At the Digikey site, there are 3 different SKUs and documentation does not really match the product. The quick start guide showed a board with enclosure.
 
Back to the Xmos site, I looked at their quick start guide. I think I have a better understanding now. The host Windows OS does not support USB2.0 audio, therefore the driver needed to be install. For MAC, the OS already support USB2.0 audio so there is no need for driver. The start up guide also said after the driver is installed, just plug in the headphone and it will play. So I think the firmware is already installed. The kit also comes with an addition board for programming the USB board. So there is no need for a programmer. The only problem I have is trying to download their software. I registered but still have not received any password. So the software driver better be in the kit or you'll need a MAC to play it.