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Old 23rd January 2011, 09:25 PM   #11
glt is offline glt  United States
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I'm glad to see more interest in Arduino. The diyaudio people have been slow in adopting software in this mainly hardware oriented hobby. But all modern chips (DACs, receivers, sample rate converters) have a software interface just waiting to be tapped. Some of the chips like the Sabre 9018 almost always require a software setup.

If you look at my bog (thanks jkenny :-) ) you will find a lot of Arduino related resources and full source code for Wofson wm8741, ESS Sabre 9018, rotary encoders, LCD displays, sony remote and my favorite the apple aluminum remote.

Regarding the use of a graphical interface, my recommendation is not to do this for a first timer as you will spend most of your time trying to make the display work whereas the effort should be spend trying to communicate with the chips. I would say get the code working first with a character LCD and then port to code to a graphical LCD. If you are just using text. The real nice thing to have is to use a touch sensitive graphical LCD.

Regarding asking questions in the Arduino forum, as another poster indicated, you have to frame the question from a software point of view. If the question is too basic or too general, then you will probably get no response. They are very helpful and share everything. That is one place where copying is encouraged :-)

I also agree with another poster proposing a section in diyaudio for microcontrollers and code.

BTW, I have two blogs because I wanted to try both blogger and wordpress :-) blogspot is the old stuff, wordpress is the new stuff
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Old 24th January 2011, 03:43 AM   #12
ialpha is offline ialpha  Australia
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Thanks for all your help and advice. As always its very much appreciated I have taken your advice glt and just ordered a couple of different size LCD from a local supplier. will start off with that. I have been looking through your blog and looks very interesting

alexcp Thanks for the info on the spectrum analyzer, will attempt this once I have rest of system up and running.

Sorry if my original post was bit vague, I have the library for the KS0108 but couldn't figure out how to do the menu. I now realise this is bit tricky for a first timer. I got some pga 2310 volume controls and am going to try interfacing with them. Later if im feeling bit more conferment with coding Ill try a LDR Light speed attenuator controlled by arduino.

jkeny I agree with you completely about learning from each other. I will be starting a new thread soon outlining my project in detail.

Thanks again for all your help..

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Old 24th January 2011, 02:27 PM   #13
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Maybe one of the sub-forums could have "microcontroller" added to it's title to attract more interest.
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Old 27th January 2011, 05:34 PM   #14
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Do you take any special precautions with grounding and / or shielding when using a micro processor in a preamp? I have two nearly identical tube preamps, one with a micro one without. I get just touch of hum (60hz) and some other noise with the micro controlled version.

Thanks

john
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Old 27th January 2011, 05:42 PM   #15
guido is offline guido  Netherlands
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use a dedicated controller which goes to sleep when there is nothing to do instead of those generic boards which don't....

But if there's an lcd around, it still has a dedicated controller running...
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Old 27th January 2011, 06:48 PM   #16
benb is offline benb  United States
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Quote:
Originally Posted by johnmarkp View Post
Do you take any special precautions with grounding and / or shielding when using a micro processor in a preamp? I have two nearly identical tube preamps, one with a micro one without. I get just touch of hum (60hz) and some other noise with the micro controlled version.

Thanks

john
The microcontroller wouldn't cause 60Hz hum, but could be causing the "some other noise." There could be a wiring issue or something indirectly related to the controller being there that causes the hum.
Quote:
Originally Posted by guido View Post
use a dedicated controller which goes to sleep when there is nothing to do instead of those generic boards which don't....

But if there's an lcd around, it still has a dedicated controller running...
There are microcontrollers with direct interfacing to LCD displays (such as the AVR Butterfly), but regardless, if there's an LCD displaying something, there are active digital lines driving it and it must be well shielded from low-level audio.

If you use a non-multiplexed LED display you can have the processor go to sleep while the display stays lit. I'm all in favor of putting the controller and its oscillator to sleep while not adjusting volume or "changing channels" (thus it's all DC idle current, no moving lines to make noise) though this can be tricky if remote control is needed.
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Old 27th January 2011, 09:26 PM   #17
guido is offline guido  Netherlands
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Not tricky. Just use the first frame to wake up and then skip it. Decode the next frame. I have this with a pic (RC5 on int line); works like a charm.

But i could not resist to put a nice VFD in later.....
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Old 27th January 2011, 09:38 PM   #18
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Thanks for the input. I am actually using a BP40 Basic Stamp. I started out with Basic stamps as a first step in learning to program and stuck with it. I use a VFD which does not contribute to the noise since it is off most of the time. I am wondering if the controller is putting garbage into the ground lines. Is there any way to isolate the controller from the rest of the ground, beyond the usual things like star grounding?
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Old 27th January 2011, 11:59 PM   #19
guido is offline guido  Netherlands
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optocouplers. I actually have used them in i2c lines:

i added volume control with relays later and used one of the power supplies for the tubes (filament). As the powersupply was designed for an additional phono stage which i don't use, the supplies were designed for three tubes / channel. As i only have the line stage i put both tubes on the supply of one channel (doesn't harm).

So i had one supply left to power the relays. But i did not want to connect the audio gnd to the controller gnd. So i used some opto's in the i2c lines and powered the relays, i2c i/o expander and uln chip with the audio supply.

I do have to say this is one way only, gets bit more complicated when there is an electronic volume where you would need to read the registers or so. Obviously i did not care about the acknowledge bit (which is the other way around). With one busmaster you don't get failures unless you really screwed up the design.

Click the image to open in full size.
The yellow ones in the middle for the relays on the left. i/o expander and uln chip are just beneith. top blue connector is for the power of that part.

Can obviously also be applied to an arduino or basic stamp.

Edit: guess you need both way communication also if you use a controller with build in hardware i2c. The hardware then expects the acknowledge and i don't know if you can disable this. I'm using an old pic with the i2c protocol programmed in software. Well part of it, as i don't do collision detection etc etc. Just the basics to get it working. You need opto's with a transistor and not those ttl to ttl thingies. It's easy to do bothway with them, you just need four then.
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Last edited by guido; 28th January 2011 at 12:21 AM.
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Old 28th January 2011, 12:17 AM   #20
glt is offline glt  United States
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Quote:
Originally Posted by johnmarkp View Post
Thanks for the input. I am actually using a BP40 Basic Stamp. I started out with Basic stamps as a first step in learning to program and stuck with it. I use a VFD which does not contribute to the noise since it is off most of the time. I am wondering if the controller is putting garbage into the ground lines. Is there any way to isolate the controller from the rest of the ground, beyond the usual things like star grounding?
There is a line of ADUM devices specially for i2c isolation...Digital Isolators | Interface | Analog Devices

After setup/adjustment, turn off the microcontroller and see if the hum goes away
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Last edited by glt; 28th January 2011 at 12:20 AM.
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