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Jambo DAC - Page 2

post #16 of 219
I'm learing verilog at the moment... finding it slightly dificult to get my head around.. any recomended reading? (my board is an Altera cyclone 2 one). So far all I have manged to code have been replacements for MSI logic chips which use about 0.1% of the FPGA :P
post #17 of 219
Thread Starter 
aamefford and cgrums, thanks for the interest - I'll keep you posted.

Currently, I have the FPGA and my board connected up but the WM8805 doesn't want to do what I'm telling it!

Kipman - there are plenty of books on it, but I always find the best way is just to get stuck in. I still have plenty of learning to do myself, but I'm pretty good on the basics. Something to bear in mind when getting your head round it is that you are coding up hardware, it isn't programming. So the next person to tell you that "Verilog is just like C" should be shot on the spot!
post #18 of 219
Thread Starter 
Hi guys,

I thought a block diagram would be more useful than the multiple schematics, hopefully everyone can get a better idea of what is going on from this.




Oh, and the software control is still not going well! It simulates great but reality, not so much. Will keep trying though!
post #19 of 219
If you really run into trouble with the FPGA (you're right, it doesn't really seem the tool for the job), I've had good success with Peter Fleury's I2C routines for AVR.

Grab a $2.50 ATtiny2313, avr-gcc, build a cheap parallel port programmer (or a kit) and you should be able to knock something together in a couple hours (assuming you know C). It's really quite fun

Looks like a nice idea. Not many DACs actually use the source multiplexers - in fact I was designing one myself the other day (not done yet). Good luck.
post #20 of 219
Thread Starter 
I have messed about in C a fair bit, but my Verilog is much better (or so I thought...). But you're right, from the point of view of cost and board space if nothing else the micro is a much better approach. I guess since I have to respin the board I might as well see how I get on with C, thanks for the links to those routines, will save me a LOT of work!

Cheers.
post #21 of 219
I have used pleanty of PIC microcontrollers and find that programing them in asyembler is far faster and easier than C If you need a high performance micro consider the SX micros (never used on but they are very fast):
Parallax SX - Wikipedia, the free encyclopedia

I dunno I have a rather low level mind and think in terms of the bits in registers so asyember is good for me (although the erata and finer points of the data sheets can bite). I managed to get A pic16F84A fast enough to record a PWM bitstream for audio recoding using 18instruction cycles per bit R/W which definatly wouldn't be posible with C (still not fast enough for high fidelity but heh).
post #22 of 219
Quote:
Originally Posted by kipman725 View Post
I have used pleanty of PIC microcontrollers and find that programing them in asyembler is far faster and easier than C If you need a high performance micro consider the SX micros (never used on but they are very fast):
Parallax SX - Wikipedia, the free encyclopedia

I dunno I have a rather low level mind and think in terms of the bits in registers so asyember is good for me (although the erata and finer points of the data sheets can bite). I managed to get A pic16F84A fast enough to record a PWM bitstream for audio recoding using 18instruction cycles per bit R/W which definatly wouldn't be posible with C (still not fast enough for high fidelity but heh).
You can easily use inline assembly for critical sections or routines in C. The compiler doesn't do a bad job either, it's smart enough to distill your bitwise statements into single bit set/bit clear instructions if it makes sense.

PIC assembly is especially strange, I never could wrap my head around it. AVR's more like architectures I used before I got into embedded, so I prefer it - and there aren't wonky memory banks. Plus the C dev tools are a lot more refined and easier to use, and I like C :P.

You're right though, for something simple like this it doesn't really matter what you use. I just assumed the OP might be more familiar with, or have less trouble learning C

Jambo, if you decide to go with AVR instead of your FPGA, drop me a line if you need any help.
post #23 of 219
Thread Starter 
Error401 - your assumption is correct, I'm quite familiar with C,though I've never used it in a microprocessor sense, so small syntax things such as allocation of output pins are confusing me a bit, I think this may be done in the inline assembly that you speak of. Thanks for the offer of help, I will send you a PM if I don't sort it out soon, my Atmel chip should be with me tomorrow and I'll see how I get on.
post #24 of 219
Thread Starter 
Allllright! The micro is setting the WM8805 up in software mode with no problems, just need to get the switches sorted out, watch this space!
post #25 of 219
Quote:
Originally Posted by Jambo View Post
Allllright! The micro is setting the WM8805 up in software mode with no problems, just need to get the switches sorted out, watch this space!
That was quick! Nice work
post #26 of 219
Thread Starter 
Hehe, thanks. Got my head around the i/o pins thing so the switches to mux the sources are working now I'm getting a slight bit of noise when changing sources, I think this must be the WM8805 locking back onto the clocks as it doesn't happen when there is no music... Then again it doesn't happen at startup so I don't really get it. The next board rev will allow me to use the micro to mute the DACs while switching sources, for the best methinks.

Also need to sort out the USB, think my PCM2707 might be fried.
post #27 of 219
Thread Starter 
Ahhaa... all working! Tomorrow I'm going to add the micro to the schematic/pcb layout and sort out the various PCB issues that I've mentioned so far, and then I'll get some new PCBs.

I've got 3 bare boards here that can be easily made to work in an optical>WM8805>dual WM8740/WM8741s>filters> RCA configuration, give me a PM if you want one cheap or hold out for the fully working one.

Error401 - thanks again for pointing me in the direction of that I2C stuff!
post #28 of 219
wow i'm interested in this - i'm interested in a group buy for parts too. I'm the uk.
post #29 of 219
Looks like you are making good progress
post #30 of 219
hey there! I'm definitely interested in ~2 boards of the next/new charge... as I've seen on the wolfson website, you can order samples online. So probably this could become a decent and (relatively) low-priced DAC!

How do you power it up at this time? Don't know how important the power supply on DACs is...

best regards and keep up that good work!
bearmann
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