Digital Pots in 5.1 System

[abid_rehan]

Reference my project of 5.1 system located at LM3886 in 5.1 system
I want to use digital pots with the system Chips like DS1802, DS1806,TDA7448 or DS1666 I find that except DS1802 and DS1666 I need a microcontroller with these chips, jus what are these microcontrollers like I2C bus, where can I get them and how can a build a volume control around a microcontroller.

Any help will be appreciated.

[Freddie]

If you want to program a microcontroller to controll a digital volume control. I suggest you use an Atmel AVR microcontroller, and use the Bascom AVR compiler. The Bascom AVR compiler is easy to work with.

I also suggest you to use something like PGA2310, WM8816 as I believe that these are better.

/Freddie

[daatkins]

I've recently completed a 5.1 system using three PGA2310 digital pots from Burr-Brown. These use the three wire SPI connection to adjust the volume - data, clock and chip select, where DATA is two 8-bit numbers to set the volume of the left and right outputs.

The following link shows an oscilloscope screen with the relationship of the three signals:
Problem controlling a PGA2310

Edit: for clarification, signal 1 is chip select, 2 is data and 3 is clock.

A microcontroller is a microprocessor with additional functions added which make it easier to use in embeded systems (as opposed to a computer). They usually have internal SPI, I2C drivers or general purpose IO pins that you can use for these functions. I used a CPLD to control the three PGA2310s but I wouldn't recommend this method to a beginner.

I2C is a two wire signal protocol. A web search should throw up plenty of links explaining more about this.

Nice one,
David.

[abid_rehan]

having seen your thread I would be very much interetsed in building one for myself except that in the poweramp section I would be using LM3886 rather than anything else could you plz post schematics of your 5.1 system, and PCB as well if u don't have any problems..
However for the microcontroller thingy I would need some more clarification..

[Hybrid fourdoor]

I plan on getting into the Microchip brand PIC's. The chips are only a ~$4 each and you can program them using Basic, which is pretty easy to understand. There are other languages too, but I like Basic, its easy to understand, and has plenty of capability for basic audio requirments.

You can even get the chips free with samples from Microchip, plus all the software is available for free. However the hardest part is getting the programer. Luckily I was able to get a DIY programmer from a local shop for $15, but I have yet to put it together. It uses a parrellel port on the computer.


This is one of the good sites for learning how to program in Basic on a PIC. MicroEngineering Labs. Here everything you need to get started.

[till]

I made my pic programmer for about 5€

http://www.sprut.de/electronic/pic/projekte/brenner5/

and use a 16F628 with internal clk for minimal parts with PGA2310 (11)

http://home.tu-clausthal.de/~tpa/PGA/index.html

[daatkins]

Abidr,
This is the schematic of the volume control section. It's fairly straight forward but a few notes on some of the other signals may help your understanding. The POWER_GOOD and RELAY_DRIVE signals sense the amp powering up and connect the speakers (via relays) after a two second delay. The up/down switch and a power-on LED are connected to J23 while J22 is used for programming the CPLD (U17). The CPLD is clocked at 4MHz by U18.

Email me if you would like the whole eight page set. Alternatively, if you prefer the schematic and layout files then I suggest you download a demo copy of the Proteus 6 software from...
Http://www.labcenter.co.uk

The demo isn't time-limited but the save and print functions have been disabled. It's a 15MB download. The schematics are 180K and the layout is 200K.

Nice one,
David.

[Mika]

Hi all!

I have also DIY 6-channel preamp controlled by PIC16F877A.

u can find microcontroller schematic here: http://ktwww.pspt.fi/w9042/uc_sch.jpg

and picture of my prototype: http://ktwww.pspt.fi/w9042/102_0263.jpg

Sorry, picture size is big (1MB and 0,6MB). I hope that u can get some ideas for your preamp. I think that it is very ambitious project to build DIY 6-channel preamp, and when its working u go in heaven (I hope u understand what i mean)

[abid_rehan]

Unlike other DIY forums I always feel comfortable in posting a thread at DIY Audio, quality of replies is very good, right now I am out of station and will give my complete feedback about your guys replies.
But thanks to u all..

[Bill Fitzpatrick]

Surely someone who is experienced and set up to do the controller chip programming could make many extras for sale to the DIY community.

I'd like to buy some pre-programmed chips.