Simple Audio DSP Module

[mhelin]

The DSP board works great except that I can't update the DSP RAM with pot values properly.  I'm able to load DSP programs over the DSP's serial bus but when I try to load data into it's RAM the values seem to get corrupted.  I'm writing to the area of memory that's considered the 16 user registers and not to the RAM that's used for sample memory.

I'm using hardware signal from the Atmel to the DSP (Atmel GPIO to DSP Input pin used as GPIO) to allow the DSP program to avoid accessing the memory when the MCU is writing to it (line is high while MCU is writing).  But this didn't solve the problem.  I don't think this is a collision or arbitration problem but rather an issue with how I'm using the serial I/O protocol.

I think the errata here has some instructions related to external serial memory access:

http://www.wavefrontsemi.com/DataSheetsFolder/WavefrontEC3101-01.pdf

[markseel]

Thanks for digging that up mhelin.  I'll give that a shot this weekend and let you all know how it turns out.  Hope it works!

[markseel]

A new revision/design of this board is about ready.  It's easier and cheaper to build but differs from the 10-pin board as follows ...

1) Two layer board with one component side (versus four layers with two component sides)
2) 16-pin DIP (600 mil wide at the pins) rather than a 10-pin SIP (board size is 0.8" x 0.7" rather than 1.0" x 0.6")
3) Uses the same AL3102 and ATtiny84 parts (minor changes to firmware though)
4) The WM8731 CODEC is gone (you hook up your own, up to four stereo DACs and four stereo ADC's)
5) The four ADC lines and four DAC lines of the AL3102's brought out to board pins
6) The I2S master clock, bit clock and left/right word clock are brought out to board pins
7) The board is the I2S master (provides all of the clocks in #6)
Uses the same Python script for compiling and downloading the DSP programs into FLASH memory
9) Allows writing to DSP RAM via serial line (board pin) for updating the DSP with pot values and such (same as previous board)
10) 3.3 volts @ 35 mA

Just like the previous board all you have to do is hook up a USB to serial adapter in order to download programs or update DSP memory with adjustment values.  But there's no low-speed ADC inputs.  But you could hook this up to another micro-controller that samples pots and write the values via the serial connection.

[DSV]

Wow, this has got me really interested!!!  

My project is to implement a FIR filter for cabinet and acoustic guitar emulation + some noise filtering for noise reduction.
I am fairly new to dsp: though I have some basic knowledge on how effects can be coded and some programming skills, it is the hardware part which I find pretty difficult to grasp. Therefore I am looking for boards with analog audio ins and outs, usb port for programming, and some cheap/free development tools to learn. What you presented seems to fit the bill, also considered that the 1024 instructions per cycle are probably much better than the 128 from the FV-1 for what I am planning to do!  

If I understood well, you are selling the boards, though I did not find any info on http://sites.google.com/site/nextaudiodsp/ . I would like to have some more info on the price and shipping (Europe) for the boards, and if you still have some "older" ones, those with the ADC - DAC. And one last question: does pretty much any USB to serial converter work for the programming of the chips?

Many thanks for your answer and this nice project,

Daniele

[markseel]

The nice thing about the FV-1 is that the audio DAC, ADC and pot interfaces are part of the chip.  Simple and compact.  But the Wavefront part is more powerful.  I've written some distortion algorithms that use nearly all 1024 words of instruction memory - there's no way I could use the FV-1 for this application (non-linear wave shaping with up/down sampling and tone filtering).

I've made a few of the 10-pin boards shown on the website so far.  I'm almost ready to ship five more.  Three people have emailed me about them.  I've agreed to send them out for free just to get them in peoples hands in order to get some feedback!  You can have the other one if you want it.  The only downside is that it's taken me a long time to get these done since I'm busy and I don't like soldering    If you want it then email me your address and I'll ship it out there.

I should have one more available after that - if someone wants it send me an email.

With the info on the website anyone should be able to build one of these boards but it obviously takes some work (order PCB's and parts, solder, burn firmware, etc).  The files are out there.  If I had more time I'd build a bunch and start selling them for $30 or so.  That was the plan but I haven't been able to scale up to that.

Yes, any USB to serial converter/adapter will work as long as the adapter has a driver that creates a virtual COM port.  All board's I've seen use one of three IC's as the USB/Serial converter.  Most are either based on an FTDI part (FT232 or similiar) or the CP2101/CP2102.  All of these have the appropriate drivers for Windows, Linux and MacOS.

This next rev of the board omits the CODEC so that people can choose their own CODEC and even use up to four CODEC's if desired.  It's easier to assemble too.  If there's enough demand then I'll build more 10-pin boards that have the WM8731 codec, otherwise I'm going to phase that board out in favor of this 16-PIN DIP board that omits the CODEC.  The long term goal is to build these this summer and sell for about $20.

[DSV]

Hi!

I've made a few of the 10-pin boards shown on the website so far.  I'm almost ready to ship five more.  Three people have emailed me about them.  I've agreed to send them out for free just to get them in peoples hands in order to get some feedback!  You can have the other one if you want it.  The only downside is that it's taken me a long time to get these done since I'm busy and I don't like soldering    If you want it then email me your address and I'll ship it out there.

That is a very kind and cool offer! I'll send you a PM!

BTW, I am checking the feasability of the project through software simulation. The acoustic guitar part is at a good point, and I should start the cab response next week ... progress is here:
http://www.diystompboxes.com/smfforum/index.php?topic=91062.0

[markseel]

Hi Everyone.  I've received some emails asking for some boards.  I'm having a hard time finding time to build these!  Does anyone have an interest in building some or having access to these boards only partially assembled?.  I could provide Atmel AtTiny84's programmed with firmware and soldered onto the board with the rest of the parts not soldered yet (WM8731 codec, AL3102 DSP, resistors and caps, 10-pin header) as a kit for cheap.  Any thoughts?

[Hides-His-Eyes]

I'd consider giving it a go.

[derevaun]

I'd go for a partially soldered kit form.