Post by thread:[PIC] or others... Are there any DIP microcontroll

On Wed, Feb 15, 2012 at 6:03 AM, Jacopo Monegato <spam_OUTjack.monegatoTakeThisOuThotmail.it>wrote: > > Hi there, I was looking for microcontrollers with analog outputs, to > reduce board size, instead of using 3-4 DACs. Google found for me some > interesting micros form analog devices, but all of them are in LFCSP > package, 5-6mm squares. Since I am a DIYer i wanted to use DIP packages, > also because i have never soldered anything smaller than DIP :( do you know > any DIP micro with analog outputs?? Some of the dsPIC33 series such as the dsPIC33FJ128GP802 has an internal DAC. There are many other PICs with analog outputs, but that one came to mind first

> I was looking for microcontrollers with analog outputs, to reduce board size, ... Analog outputs will almost invariably be digitally based anyway. ie PWM (analog when filtered) or DAC (digitally quantised steps) based. If you search eg Digikey for microcontrollers wityh DAC you should find something. BUT if you use PWM with a simple RC fulter it will suit many needs and then ANY digital pin can be an analog output. BUT if you want max DACs in minimum DIP package, this seems to be gard to beat. 4 x 9bit DAC in DIP8 !!! Cypress PSOC. CY8C27143-24PXI Datasheet http://www.cypress.com/?docID=31789 In stock Digikey $5.32/1. Weird by normal standards is the price you pay. Russell McMaho

yes, i think so... I need possibly more than 9 bit precision. What i am trying to do is digital control of an analog audio vco. I need veeeeery low noise ;) I know that some brands, like Dave smith instruments use 8 bit precision for vcf cutoff and even pitch wheel (in older instruments). I want more. I wanted to avoid PWM. In that case I would have used a third order butterworth vcvs to have about 0,5-1 mVpp noise, but i wanted to try something else. But, at this point, i guess i'll stay on pwm :/ Thank you all! > Date: Wed, 15 Feb 2012 12:25:30 +0100 > From: .....jan-erik.soderholmKILLspam@spam@telia.com > To: piclistKILLspammit.edu > Subject: Re: [PIC] or others... Are there any DIP microcontroller with analog outputs? > > Jacopo Monegato wrote 2012-02-15 12:03: > > > > Hi there, I was looking for microcontrollers with analog outputs, to > > reduce board size, instead of using 3-4 DACs. Google found for me some > > interesting micros form analog devices, but all of them are in LFCSP > > package, 5-6mm squares. Since I am a DIYer i wanted to use DIP packages, > > also because i have never soldered anything smaller than DIP :( do you > > know any DIP micro with analog outputs?? > > > > Jacopo Monegato > > Yes. Some newer (16F-) PICs has a 5 bit DAC. > And at the high end, I think the dsPIC's has "better" DACs. > -

> -----Original Message----- > From: .....piclist-bouncesKILLspam.....mit.edu [EraseMEpiclist-bouncesspam_OUTTakeThisOuTmit.edu] On Behalf > Of Jacopo Monegato > Sent: 15 February 2012 12:06 > To: piclistspam_OUTmit.edu > Subject: RE: [PIC] or others... Are there any DIP microcontroller with > analog outputs? > > > yes, i think so... I need possibly more than 9 bit precision. What i am > trying to do is digital control of an analog audio vco. I need veeeeery > low noise ;) I know that some brands, like Dave smith instruments use 8 > bit precision for vcf cutoff and even pitch wheel (in older instruments). > I want more. I wanted to avoid PWM. In that case I would have used a third > order butterworth vcvs to have about 0,5-1 mVpp noise, but i wanted to try > something else. But, at this point, i guess i'll stay on pwm :/ > Thank you all! > The ATXMega128A1 has four 12 bit DAC channels and is available in TQFP which really not very difficult to solder, as long as you soldering iron isn't designed for plumbing application! If DIP is preferable for bread-boarding you can get TQFP/DIP converter PCBs http://www.atmel.com/products/microcontrollers/avr/avr_xmega.aspx Cheers Mike ======================================================================= This e-mail is intended for the person it is addressed to only. The information contained in it may be confidential and/or protected by law. If you are not the intended recipient of this message, you must not make any use of this information, or copy or show it to any person. Please contact us immediately to tell us that you have received this e-mail, and return the original to us. Any use, forwarding, printing or copying of this message is strictly prohibited. No part of this message can be considered a request for goods or services. =======================================================================

> yes, i think so... I need possibly more than 9 bit precision. What i am trying to do > is digital control of an analog audio vco. I need veeeeery low noise ;) I know that > some brands, like Dave smith instruments use 8 bit precision for vcf cutoff and even > pitch wheel (in older instruments). I want more. I wanted to avoid PWM. In that case > I would have used a third order butterworth vcvs to have about 0,5-1 mVpp noise, but > i wanted to try something else. But, at this point, i guess i'll stay on pwm :/ > Thank you all! You might get 16 bit precision in a micro, but I doubt it will be low noise.. There is a reason that these extra bits of accuracy are not commonly available ... If you really need lots of precision then an external DAC will be the only way. It will also allow you to lay out grounding in a manner that will allow you to use the extra bits, and get the noise level you are after. -- Scanned by iCritical.

Jacopo Monegato wrote: > yes, i think so... I need possibly more than 9 bit precision. What i am > trying to do is digital control of an analog audio vco. I need veeeeery low > noise ;) I know that some brands, like Dave smith instruments use 8 bit > precision for vcf cutoff and even pitch wheel (in older instruments). I want > more. I wanted to avoid PWM. In that case I would have used a third order > butterworth vcvs to have about 0,5-1 mVpp noise, but i wanted to try > something else. But, at this point, i guess i'll stay on pwm :/ What kind of bandwidth (sample rate) do you need? If not more than 100 Hz or so, it sounds like you should consider doing delta-sigma in firmware, which is much cleaner (easier to filter) than PWM. Linearity is excellent, and resolution is really just a question of the width of the variables you use in the firmware. For example, here's some C-ish pseudocode that implements N_CHAN channels of 15-bit DAC. The dac_isr() should run as frequently as possible, at least 10x to 20x the bandwidth that you desire. If you do this in assembler, then you can squeeze out another bit of resolution, because then you can use the carry bit out of the addition operation instead of the MSB of the accumulator. You might also want to unroll the loop, which makes mapping channels to output pins trivial. ("u16" and "u8" denote unsigned 16- and 8-bit integer types.) struct { u16 value; /* sets the output level of this channel, 0 - 0x7FFF */ u16 acc; /* internal accumulator (integrator) */ } ch[N_CHAN]; /* Timer interrupt handler */ void dac_isr (void) { u8 i; for (i=0; i<N_CHAN; ++i) { ch[i].acc += ch[i].value; if (ch[i].acc & 0x8000) { ch[i].acc &= ~0x8000; /* set the output bit associated with channel i */ } else { /* clear the output bit associated with channel i */ } } } -- Dave Twee

I am currently using PWM with an active third or fourth order butterworth in another project... a little board with a 16f876a used as a replacement to the original pcb inside a 25 key laptop-size usb keyboard to convert it in a cv-gate keyboard.. I haven't finished it yet because i have to go buying a couple of other ICs first, in that case i would run at 18MHz, pwm at about 15kHz to have high speed and all the 10 bits.. and filter at about 200-300 Hz. With a simulator I obtained good results, in the next weeks i'll make and test the board. Anyway, I think 10 or 12 bits should be fine.. I think I I have a couple of mpc4822 but I didn't want to use them now... My idea is to continously acquire alle the knobs values, sum or subtract them via software, store them in a memory (so i can quick recall patches, configurations, ...) and use the dac to feed the result in the oscillator circuitery, so, basically they would be constant values {Quote hidden}> Date: Wed, 15 Feb 2012 07:59:57 -0500 > To: @spam@piclistKILLspammit.edu > From: KILLspampicKILLspamdtweed.com > Subject: Re: [PIC] or others... Are there any DIP microcontroller with analog outputs? > > Jacopo Monegato wrote: > > yes, i think so... I need possibly more than 9 bit precision. What i am > > trying to do is digital control of an analog audio vco. I need veeeeery low > > noise ;) I know that some brands, like Dave smith instruments use 8 bit > > precision for vcf cutoff and even pitch wheel (in older instruments). I want > > more. I wanted to avoid PWM. In that case I would have used a third order > > butterworth vcvs to have about 0,5-1 mVpp noise, but i wanted to try > > something else. But, at this point, i guess i'll stay on pwm :/ > > What kind of bandwidth (sample rate) do you need? > > If not more than 100 Hz or so, it sounds like you should consider doing > delta-sigma in firmware, which is much cleaner (easier to filter) than PWM. > Linearity is excellent, and resolution is really just a question of the > width of the variables you use in the firmware. > > For example, here's some C-ish pseudocode that implements N_CHAN channels of > 15-bit DAC. The dac_isr() should run as frequently as possible, at least 10x > to 20x the bandwidth that you desire. If you do this in assembler, then you > can squeeze out another bit of resolution, because then you can use the carry > bit out of the addition operation instead of the MSB of the accumulator. You > might also want to unroll the loop, which makes mapping channels to output > pins trivial. ("u16" and "u8" denote unsigned 16- and 8-bit integer types..) > > struct { > u16 value; /* sets the output level of this channel, 0 - 0x7FFF */ > u16 acc; /* internal accumulator (integrator) */ > } ch[N_CHAN]; > > /* Timer interrupt handler */ > void dac_isr (void) > { > u8 i; > for (i=0; i<N_CHAN; ++i) { > ch[i].acc += ch[i].value; > if (ch[i].acc & 0x8000) { > ch[i].acc &= ~0x8000; > /* set the output bit associated with channel i */ > } else { > /* clear the output bit associated with channel i */ > } > } > } > > -- Dave Tweed > -