microcontroller for simple audio project
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From: Buddy Smith on 2 Feb 2005 14:43 ethan <ethan(a)dspmusic.org> wrote: > hi, i'm looking for a uC for a simple portable audio project. the > basic specifications i'm looking for are: <snip> I think more useful information could be given if you said what this 'simple audio project' was. What exactly does your micro need to do with audio? ttyl, --buddy
From: Walter Banks on 2 Feb 2005 15:04 For audio outputs why not do it the way a cd does with a single digital output through a low pass filter. This is the same as the sigma part of a sigma delta codec. You can get a surprising amount of resolution with just a single resistor and capacitor. The code to drive such a D/A is a few lines of C w.. ethan wrote: > thanks for the reply! > > DAC resolution: basically just something that matches the native > datatype of the processor. since i'm pretty sure i'll be using an 8 > bitter, 8+ bits of precision should be fine. > > TI MSC: hmmm, this might be worth looking into. the MSC1202Y3 is > pretty similar to the SI Labs part i'm considering. that said, i'd > rather not pick a TI part since i work for analog devices. ;) > > ADUC841: speaking of analog devices, that one looks pretty good. lots > of memory for the price. if 8k FLASH won't cut it, this looks like a > viable option. > > ADUC702x: those look great, but i bet the price is going to be too > high. plus there's that whole not existing thing to contend with. > > atmel ARM7 uC: i like these, but i think they were going to be too > pricy. plus there's no integrated DAC and i'm trying to keep this as > simple as possible. > > as for whether an 8052 will have the power for an audio app, i suppose > that really remains to be seen. i have some synthesis code written for > an ADSP-218x DSP, need to try porting a bit of it to find out just much > i'll be able to get done.
From: Ulf Samuelsson on 2 Feb 2005 14:58 This message is intended to be my own personal view and it may or may not be shared by my employer Atmel Nordic AB "ethan" <ethan(a)dspmusic.org> skrev i meddelandet news:1107357766.818450.151450(a)o13g2000cwo.googlegroups.com... > hi, i'm looking for a uC for a simple portable audio project. the > basic specifications i'm looking for are: > > - 8/16 bit datapath > - hardware multiply (8x8 ok, more bits the merrier) > - 20+ MHZ instruction execution > - onboard flash/SRAM (8kbytes+ FLASH, 1kbyte+ SRAM) > - UART > - onboard DAC (mono ok, stereo better) > - free build tools > - cheap! > > right now i'm looking at the SI Labs C8051F330. it's right at the low > end of most of my criteria, but it's the only inexpensive uC ($4.27 > quantity 100) i've seen with an onboard DAC. does anyone out there > have experience with this part? also, is there something else i should > be looking at? SI Labs have some larger FLASH variants (for example > the C8051F017) but they sell for $12 in similar quantities, so that's > out. the atmel AVRs are appealing for a number of reasons, but they > don't have a DAC. anyone aware of a cheaper option than the C8051F330 > for a full uC/flash/DAC system? is there a good very cheap DAC one > could easily interface with an AVR? > > i'd love to use a DSP, but i believe they're just too pricy and don't > come with the level of integration i need. feel free to prove me wrong > on this assumption. > > thanks a lot for the help! > May not meet you price tharget but the AT89C51SND2 has both MP3 player decompression and a DAC. If you store lots of audio, then the compression may allow you to save on memory. You can use rsiastors or PWM to generate a DAC. The new AT90PWM parts (which are hard to get) have 12 bit Resolution enhanced PWM from a 64 MHz input source which could be useful to generate a DAC. The high frequency allows you to use small components.. The 5V ATmega88 should meet your requirements if you use an 8 bit port and an external resistor ladder. -- Best Regards, Ulf Samuelsson ulf(a)a-t-m-e-l.com > ethan >
From: ethan on 2 Feb 2005 15:27 sure no problem. basically i'm looking to create an extremely simple autonomous synthesizer. waveforms would be generated through wavetable synthesis (with linear interpolation if i can afford it) and others through simple bitshifting algorithms and reading noise buffers. there will also be some simple FX (FIR filters and other more novel but cheap functions), envelopes, and a basic sequencer. as for sampling rate, it's TBD. i just need to be able to generate enough channels of audio to make something interesting, then i'll set the sample rate as high as my MIPS with allow. no MIDI, at most some rudimentary interaction via knobs or pushbuttons. i've implemented all of this on a DSP (see www.dspmusic.org or www.dsperado.com/chiclet for some info), but the total manufacturing cost is going to be too high, so i need to move to a uC. i know i can make reasonably good music with a 33MHz ADSP-2181; i'm hoping that if i cut some corners i can make something passable with a 20MHz 8052. ideally the processor would have a DAC and flash onchip for lower system cost. the DAC is proving to be the tough request; only a couple manufacturers include them in low cost processors. once i start looking at things like a standard product ARM7 the price difference between them and a DSP is pretty small, so there's little advantage to port. however getting a whole system on chip (like the C8051F330) for ~$4 is quite enticing.
From: ethan on 2 Feb 2005 15:32
i've thought about this, but am concerned about MIPS and power consumption. any idea on the processor overhead to implement this? is this something that could be implemented with PWM or a typical uC timer allowing for very low overhead? i want as many cycles as possible to calculate new outputs, so i'd rather not be stuck shifting bits. an onboard parallel DAC seems like the easy choice, but since i'm trying to be very cheap, i might not have the luxury of going the easy route! |