[ujamerstand]

Quote:

Originally Posted by ShaneP /img/forum/go_quote.gif i2s is only used for audio afaik. i2c is a separate bus and is used for commands and other i/o.

I see. Thanks for telling me! Now you see what a newb I am, and how much more research I must do...

 

[GeWa]

Is this still going anywhere?

Regards

 

[amb]

Yes, in fact. While the thread had been quiet, linuxworks and I have worked on this quite a bit. He is focused on the firmware while I have been working on the schematic for the relay attenuator and relay input/output selector modules. We hope to show more in this thread soon.

 

[GeWa]

Thanks for the update Ti.

Regards

 

[linuxworks]

yes, as amb has said, stuff has been going on, just mostly r/d stuff. I took a detour to try out a digital pot and see if it was usable directly in the audio path. turns out it wasn't. oh well. but wouldn't know that until I tried. also got some experience which will pay back later, I hope.

on the attenuator front, just yesterday I finally got the first version of code working. latching relays are tricky and it took some thinking to find a successful strategy on how to 'click them', not consume huge amounts of current at once and also to minimize audible clicks in the path. it was only about 100 lines of code but still, it was all brand new code that I had to develop from scratch, along with the strategy.

good news is that the proto IS working, we have a schematic and are working toward pcb layouts. I always like to have at least 1 working proto before moving forward and now we can really do this.

 

[MASantos]

This is great news. While there are good relay att and source selectors out there, the way AMB (and you linuxworks) documents and supports his projects is much better.

Looking forward to this!

Manuel



Quote:

Originally Posted by linuxworks /img/forum/go_quote.gif yes, as amb has said, stuff has been going on, just mostly r/d stuff. I took a detour to try out a digital pot and see if it was usable directly in the audio path. turns out it wasn't. oh well. but wouldn't know that until I tried. also got some experience which will pay back later, I hope. on the attenuator front, just yesterday I finally got the first version of code working. latching relays are tricky and it took some thinking to find a successful strategy on how to 'click them', not consume huge amounts of current at once and also to minimize audible clicks in the path. it was only about 100 lines of code but still, it was all brand new code that I had to develop from scratch, along with the strategy. good news is that the proto IS working, we have a schematic and are working toward pcb layouts. I always like to have at least 1 working proto before moving forward and now we can really do this.

 

[ujamerstand]

Very Nice. Which relays will the pcb support? Are we going to see a dedicated supply of latching relays at Ti's audio shop? Both Mouser and Digikey are a little low in supply for these things...

 

[Olli1324]

Oo-er, posted in the wrong thread :/

As I am here, though, I may as well say I'm particularly excited about this new project.

 

[vixr]

this is going to be fabulous...I cant wait to play with this stuff...

 

[jtostenr]

ok, I have a noob question...

I know the LCDuino requires it's own 5V power source, but what about the input selector and speaker/headphone switch? Will they draw power from the LCDuino, or do they require their own power source?

Jeff

 

[linuxworks]

the lcduino does not draw that much power on its own. I have a sigma25 (7805) powering one of mine with about 7vac going into it and it barely gets warm to the touch.

it would depend on what the downstream things need. the relay module is designed NOT to eat current (we took extra pains to do this). the relays are 'strobed' a few at a time (configurable) and are only clicked for a few ms before they are 'relaxed'. this keeps the peak current down, as well. the relay board needs only 5v and so far, with my proto, its drawing off the same s25 as the lcduino1.

other 'client' boards may need special power. the PGA chip proto I built needed dual 12v or possibly dual5 (if the DIP version was used). it also needed a logic 5v and that could come from the lcd1 but for isolation reasons, I would give it its own clean 5v.

input selector follows the same latching relay scheme as the attenuator, so that can very easily use the same s25 supply as the lcduino1.

output selector MIGHT be different as it would benefit from a higher current (contact) relay. if we can find a 5v dc latching relay that 'carries current' that would be great. else, that relay may have to be driven by a transistor or equiv and most 'heavy duty' relays I've seen are 12v for cars (nice heavy duty ones easily found) or 24v. some even higher voltage. so the output selector might be the only non-latcher here and that means it takes current when its in its 'down' position. when I made my output relay module, I picked the normally-open contacts to be for the phones and NC contacts for spkrs since I tend to use my b22 (which has the relay in it) for spkrs more than phones. if you use it the other way, you may want to define the NC contacts for phones.

 

[jtostenr]

Thanks Linuxworks, that helps alot. Do you know what the approximate sizes of the attenuator, input and output selector pcbs are going to be yet? Just looking for an estimate so I can work on my layout.

Jeff

 

[amb]

I am working on the PCB layouts but I don't have a firm size to report yet. Sorry.

 

[Listen2this1]

Is it going to fit in an Altoids tin?

 

[amb]

Not likely.