TOPIC:

Doesn't that say i2c? is that the same as i2s?

pcpete, you're correct. This chip won't work since it is for I2C and not I2S.

You'll just need a simple high speed buffer (e.g. 74ac244) or a dedicated clock fanout buffer (e.g. CDCLVC11xx from TI). However it is important to take the propagation delay of the buffers into account if you use several ICs.

I'll check several things and will report! Might take some time though...

Best regards, Daniel

Another Update:

I have one of the new boards up and running and I am very pleased with the sound
Great dynamics and a wonderful timbre - another step ahead from the first version.

I'll probably make some boards available if there is interest, however this may take a little more time...

The stuffed board:


My listening setup with miniSTREAMER, DAC Board (ES9023 + MCLK Supply: 9V Battery, Analog output Buffer Supply: Salas Shunt ), HEAD acoustics HD IV.1 Headphone (selected Sennheiser HD600):



Cheers, Daniel

Good stuff curryman! Have you tried running more than 1 dac on a minisharc yet?

What I'm really looking for is a nice stackable or single board 8ch dac that would integrate nicely with the minisharc....anyway that 3 or 4 of your dacs could fit this bill?

[quote="curryman" post=8671
For the connection of the I2S signals from miniSHARC to my DAC I designed a passive interface board (see attached picture). @Devteam: do you see any problem with miniSHARC driving the paralleled I2S receiver. If anyone is interested please let me know.



I am also about to design an active interface board using high speed fan out buffers and the possibility to provide a precision MCLK Signal to all components (receiver, miniSHARC [24.576 MHz], ES9023 DACs [49.152 MHz]). The latter will of course only work with miniSHARC I2S slave firmware [/quote]

I think the website changes have meant that some of the old attachments are gone now unfortunately. I have a similar project in mind, though not using your DAC pcbs will still have ES9023 and JG filterbuffer and minisharc.

How did you go with the passive and active designs you mention above?

I started designing my own active adapter PCB before stumbling across this thread and I'm hoping to have design finished within the next week, still tossing up whether to put the MCLK XO on the adapter board, I already have another PCB that will do the job, but I don't want to create beast of a 100 PCBs either. So far what I'm targetting is:

- Isolators between minisharc and DAC output,
- reclocking in FF based on an external clock.
- Regardless of XO on board or off board I will use 49.xxx MHz master clock for DAC and as the CLK input on the reclocking flip flops.
- MCLK/2 will be available when minisharc slave mode firmware becomes available.
- minisharc mclk output (0603 jumper replacement required to to swap between minisharc slave/master mclk mode)


I need to check u.fl cable impedances and decide if the buffers in the FF will support driving 3 u.fl cables to 3 DACs for MCLK, BCLK and LRCLK. Might do two PCB designs, one with clock buffers and one with additional ufl socket in parallel.

I'm interested to see how things are progressing with your adapters! I'll throw up a pic of my layout later in the week.

Good to see that someone is working on that since I haven't had the time to proceed

Just today I finished setting up my miniSHARC with three of my DACs, which I connected point to point wiring first. However it does not work so I have to troubleshoot
Actually can't measure any signal on the I2S lines so there might be a bigger problem. I'll probably detach the DACs again and see what happens...

Your list sounds great and it's quite the same I had in mind. As you might have heard also miniDSP is working on an adapter board (originally for Buffalo III) featuring buffers. What FF are you going to use? What about differences in propagation delay between several flip flops? Do you have any idea if this may be a problem?

Best regards, Daniel

I'd remove one DAC at a time I think. Cable capacitance will be a problem if you've got 3x MCLK in parallel. I did some sums today thinking about parrallel vs buffers on the clock lines, with 3 x u.fl in parallel and some conservative estimates for output capacitance, input capacitance and PCB capacitance, you easily get to 80pF. I don't have numbers off the top of my head for point to point wiring, but that will be worse again I'd expect. This will mean that ringing and distortion on the clock signal won't be great.

Though maybe if you're saying there is no signal at all showing, that could be something different entirely.

I'm going to use the potatosemi flipflops and probably use a 1.4mm two layer PCB for impedance control since those FF have a tr of 0.8ns it gets a bit important to know that it's under control!

Well, the mistake was on my side

I am using an early Version of the miniSHARC which needs an additional adapter board (miniSHARC I/O card) on top to connect to Vol-FP etc (some connectors are missing on my miniSHARC that are available at actual boards). The I/O card stacks on top of the miniSHARC and has the same 30pin headers like it. However J2 on I/O card is NOT connecting to J2 of miniSHARC (just different naming). I was looking for the I2S signals at J2 of I/O card but couldn't find it. Now I know why

After connecting my DACs to J3 at the I/O card (which actually connects to J2 on the miniSHARC) everything works fine

I2S Signals look quite OK with three DACs connected (as far as I can analyze with my 50MHz scope):



As you can see I used ribbon cables to connect to miniSHARC. Unfortunately the pin headers at the miniDSP don't have GND - signal - GND - signal - ... arrangement and thus ground return is not very well organized . I agree that a buffer will be better in this case!

Though with ES9023 I don't use external MCLK and thus frequencies aren't that high (3MHz for BLCK). Now I will go to Frickelfest this weekend and afterwards I plan to install buffers...

Best regards, Daniel

Looks neat!!

I know what you mean about the pin layout of ground connection the minidsp header, I think the adapters will help reduce that problem at least I didn't know that minidsp were doing one for the BIII, I'd like something a bit more tailored to my needs than bending something else to suit me. I might two versions of my layout, one with reclocking sections removed.

Important to remember that the bandwidth is defined by rise time not the duty cycle of the square wave too, so even though 3MHz BCLK is all you're using you might still need a bandwidth of 90-100MHz to support a rise time of say 5ns (assumed conservative guess, no idea what the rise time is, need minidsp to tell us I suspect, or perhaps the DSP chip datasheet would shed some light on the issue).


What back panel connector are you using for optical? I spent some time a while ago looking for a D-size optical connector but the neutrik ones I found looked to be for dual fibre or something else, not optical spdif.

Chris

You're absolutely correct with the bandwith! 5ns might even be a bit high, could also be arround 2ns So it really helps to get things right

The Neutrik Toslink connectors are just simple feed through adapters from Switchcraft . Not perfect but works most of the time (you have to make sure both ends are sitting tight so that signal can transmit). I am only using it for TV sound

Best regards, Daniel

Hi Curryman.

Great project!
I'm curious if you or hochopeper made any progress on the I2S interface/buffer board. I'm currently integrating a MiniSHARC (as 2x8 XO) into a system with a PreXO board and a 8 channel digital poweramp (actually 4 2-channel amps), and will probably be needing some kind of buffering to. (I will post details of my project incl. pics in this section later this week).
I'm thinking in the line of reclocking with 74AUP1G79, but not sure which way to go with the fanout buffering. Just curious if one of you made some progress on the design already

Regards, Emiel

Hey Curryman!

I recd my DAC boards and Minishark.

looks good!

I want to simplify the I2S out connections from the Minisharc to the your DACs. looks like ribbon cable with IDC connections are the way to go.

are you only connecting DATA out and gnd to your DACs?

cheers

Hi Emiel,

I had an almost complete version of my isolator designed but got caught up with other things in 2nd half of last year.

I'm now changing it to a more generic interface card aimed at the miniSHARC, purpose is to provide input options for one or two i2s input ports as well as spdif and toslink inputs. It will also have a basic analogue input for those not keen on spending up on fancy ADCs for analogue sources or in my case I'll probably use that for input from a Home Theatre AVR.

For outputs I'll probably use isolated and fanout buffers for i2s outputs but later I was going to try out a circuit similar to what miniDSP use on the output of the nanoDIGI and create 4 x SPDIF outputs.

Cheers,
Chris

Builder wrote:

Hey Curryman!
I recd my DAC boards and Minishark.
looks good!
I want to simplify the I2S out connections from the Minisharc to the your DACs. looks like ribbon cable with IDC connections are the way to go.
are you only connecting DATA out and gnd to your DACs?
cheers

Besides DATA and GND you need to connect LRCK and BCK! The latter should be feed through the (stacked) DACs. The star type layout shown above also works but signal quality is better when a BUS is used.
@hochopeper: We should get in contact since I almost finished quite the same (also the same situation: no free time to finish)
regards, Daniel

curryman wrote:

@hochopeper: We should get in contact since I almost finished quite the same (also the same situation: no free time to finish)
regards, Daniel

Sent you a message just now, I think it will go through to your email?