[sdiy] PIC help

[thx1138]

On 6/7/09 6:28 PM, "Scott Juskiw" <scott at tellun.com> wrote:

> For the third time in as many years I'm making an attempt to venture
> into PIC development because all the new synth modules I want to build
> would benefit from a digital controller of some sort. I spent most of
> the weekend going over the sdiy archives and microchip website but
> sadly, am once again flummoxed by the options and am wondering if
> someone can answer a few newbie questions.
> 
> Maybe it would help if I explain my situation. My current project is a
> programmable filter bank with the following requirements:
> 
> a. 10 (at most) analogue inputs for reading pots, 10 bit ADC would be
> fine
> b. a few digital inputs for reading switches and pushbuttons
> c. 24 analogue outputs to control filter frequency, Q, gain etc, 12
> bit DAC would be fine
> d. EEPROM for storing presets
> e. ability to hook up an LCD display (2 line by 40 character or smaller)
> 
> 1. What programmer/debugger do you use or recommend? I don't want to
> build one, or get some third party box. I've narrowed the choices down
> to either the PICkit 3 ($70) or MPLAB ICD3 ($220) and am wondering if
> there's any significant advantage to the ICD3 that makes it worth
> being 3X as much as the PICkit 3.
> 
> 2. How do you decide which PIC chip to use? I know some of you are
> using the dsPIC33FJ128GPxxx series (Tom, Seb, Eric) and I'm more than
> happy to follow your lead, but it might be overkill for my needs. But
> they aren't too expensive, should I just go with the flow and use the
> latest and greatest chips?
> 
> 3. Some of the dsPIC chips have a built-in 16-bit DAC but it appears
> to be best suited for two channels of audio, not for 24 channels of
> control voltages. Would I be better off using an external DAC to get
> 24 analogue outs and avoid the internal DAC?
> 
> 4. If using an external DAC, is there any advantage to using one DAC
> with lots of multiplexing to get 24 outputs vs. using several 8-
> channel DACs (e.g. TLV5610)?
> 
> 5. It seems that dsPIC chips don't have enough built-in EEPROM to
> store all the info I want for the presets. Is it best to avoid trying
> to max out the internal EEPROM and use an external EEPROM? (I see that
> Seb has hooked up an EEPROM to his Digi-Mod.)
> 
> 6. What do you recommend for an LCD display (2x40 character or less)
> that would be simple to hook up to a PIC? Do these things have some
> kind of common interface (SPI)?
> 
> Thanks for your help and guidance.
> 
> 
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Hello Scott,

What about the Freescale MCU's for this application?

The Compiler tools CodeWarrior are free and all of the 9S08 based devices
have BDM (BackGround Debug Mode) built into the devices.

The DSP568xx have MUC and DSP funtionality as the dsPIC  devices as well.

The DSP56371 has a 24-bit FIR-IIR Filter co-processor built into the device.
Add a simple MCU for Flash and Display and a AKM Codec and you can build a
pretty powerful Filter bank. The DSPB56371 has a Graphic-EQ, Parametric EQ,
Compressor-Limiter, Digital volume control etc. built into the ROM for FREE.

Check out the http://www.freescale.com/symphony page and look up the
SoundBite board. All of the DSP tools are free as well.

Just my 2 Cents.

Terry Shultz
DSP and ARM Audio Technology
Freescale Inc.