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Hey. Received the Otto-II - thanks! In my application (eXD USB/DSD board with separate headers for PCM & DSD), I need to be able to toggle between DSD or PCM on the front panel. Being the raw newbie that I am, I'd really appreciate some concrete example of the sort of switch I need, and the wiring of such. Thanks!
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Here is a simple diagram for using an SPST switch. EDIT: In the diagram, I used a pull-down resistor and switched V+. You could just as easily use a pull-up resistor (between S and Vcc), then switch GND and S. Also, instead of a switch, you can just drive S directly from a micro-controller GPIO pin, though I would probably add a resistor (2K-10K) between the two. Edited by user Thursday, August 9, 2012 1:29:25 AM(UTC)
| Reason: Not specified Brian Donegan attached the following image(s):  OTTO_SIMPLE.jpg (188kb) downloaded 177 time(s).You cannot view/download attachments. Try to login or register.
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Thanks Brian - this is exactly what I needed.
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That's a very good diagram by Brian, but I would suggest using a pull up resistor for the "S" signal (4.7 - 10K is fine) and witching to ground instead of the other way around. Edited by user Thursday, August 9, 2012 3:24:01 AM(UTC)
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The reason is that the resistor limits any possible current to the gate - should catastrophe strike. If the gate is directly connected to to VD you don't get that protection.
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When using Arduino to switch between two sources it should not be a problem to use Brian's diagram, right? This seems like the easiest approach to me using Arduino.
When I set S high using one of Arduino's pinouts it will enable an internal 20K pullup resistor and therefore limiting any possible current to the gate. |
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You usually only use internal pullups for an input.
In the cause of the OTTO-II with a micro-controller you could either directly drive "S" with an output. If that output is a open drain type you would still use the pull up resistor on the OTTO-II.
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So I wired up Otto II with streams coming from the I2S and the DSD pinouts on the eXD board. The eXD board exposes a high/low pin that I'm using to switch between I2S and DSD. It works - but needs to warm up first. It's very strange. On cold start, no signal, no lock. After a couple of minutes, it begins to get lock very couple of seconds (I2S & DSD). This improves until both streams are stable. I have DPLL bandwidth set to highest (5,6,7 are on).
Otto simply has VDD/Ground & S wired. Any thoughts? If I bypass Otto, all's well (but of course I have to choose between streams).
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You do have OE pulled to GND right?
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Also make sure that your signals go no higher than VD. If you signal is 3.3V then VD should be at least 3.3V and 5V would be better.
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Thanks Russ - that was the problem. VD is ~5. It's rock solid now.
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I appreciate the diagram Brian! I installed the Otto in my Denon 3910 to switch between PCM/DSD tonight. I 'learnt' that while Otto works without a resistor between S and GND, it takes a while for it to switch back to B1 when I flipped the switch; in other words it stays locked on B2 for a bit. With the resistor in place, B1 and B2 switch instantly when I open and close the SPST switch. I also found the GND had continuity from the B1 to B2 side so I didn't jumper the ground over from B1 to B2. Otto works great! It saves a bunch of work versus making a multiple relay board for my CD/SACD player. In the Denon 3910, DSD and PCM share two inputs into the DAC chip which saves running extra wires (I just need 5 wires for PCM/DSD output, with one being the ground). But the left and right channels swap on those circuits in DSD. I just had to change the connection order for two wires jumping over from the B1 side. EDIT: Yeah, the terminals were not pushed in all the way in the connector on the B2 side until I was sure the DSD channels were not reversed.  Oh, I don't think they make 5 terminal connectors so I started at terminal 2 so the four terminal plug would connect to the GND pin on the B1 side and the output. Edited by user Monday, August 27, 2012 3:59:04 AM(UTC)
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Originally Posted by: Russ White  That's a very good diagram by Brian, but I would suggest using a pull up resistor for the "S" signal (4.7 - 10K is fine) and witching to ground instead of the other way around. Like the attached pic? felipe attached the following image(s): resource.jpg (167kb) downloaded 102 time(s).You cannot view/download attachments. Try to login or register.
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No, please look at page 20 of the latest guide.
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