On Feb 12, 9:46=A0am, Jon Kirwan <j...@infinitefactors.org> wrote:> On Wed, 11 Feb 2009 23:20:12 -0800 (PST), -jg > > <Jim.Granvi...@gmail.com> wrote: > >> I'm seeing towards $4. =A0But then I won't really know until an order =is> >> placed. =A0Can you say anything about the tool chains you've experienc=ed> >> for this device? =A0Cost, support reponsiveness, etc. =A0Alternative > >> development tools you looked at but didn't actually wind up trying > >> out? > > >Not on this family yet, but I did like the look of the Peripheral mix, > >so it is on our radar for future use... > >. > >Very fast ADC, and high resolution timers. > > Yeah. =A0I'm impressed. > > >TI are pushing some low-cost stuff > >Experimenter Kit w/ControlCARD I see in stock at Newark for ~$82, > >Piccolo controlSTICK is a USB stick, for $40.50 > > >so that would be an easy way to quickly try the latest tools ?. > > I suppose so. =A0I'm a little disappointed looking at Eclipse > development tool costs for active development (not trial stuff.) > That's kind of off my radar range, if I decide to go that way. =A0Which > means I need to dig a little deeper about tools. =A0But yes, the device > appears attractive to me and I definitely appreciate the pointer. =A0I > think I'd heard the name dropped here once or twice, but never took > notice before. =A0But my head is turned now. =A0So I'll put a little > effort into looking further. > > JonBe vary, that F28xx (including the picolo family) internal ADC does not deliver the promised 12 bits. Event the TI acknowledge this and state thet the ENOB is around 10 bits (that was for the first members of the family the F2812). For more info on this take a look at comp.dsp and comp.arch.embedded archives and TI forum https://community.ti.com/forums/t/3165.aspx The TI improves the ADC module each generation, but I can not tell you how the picolo series ADC behaves Regards, Mitja
arm7 core with fast monolithic 12-bit ADC
Started by ●February 11, 2009
Reply by ●February 12, 20092009-02-12
Reply by ●February 12, 20092009-02-12
On Thu, 12 Feb 2009 02:30:25 -0800 (PST), korenje <korenje@yahoo.co.uk> wrote:><snip of my interest in the piccolo>>Be vary, that F28xx (including the picolo family) internal ADC does >not deliver the promised 12 bits. Event the TI acknowledge this and >state thet the ENOB is around 10 bits (that was for the first members >of the family the F2812). For more info on this take a look at >comp.dsp and comp.arch.embedded archives and TI forum >https://community.ti.com/forums/t/3165.aspx > >The TI improves the ADC module each generation, but I can not tell you >how the picolo series ADC behavesThis doesn't surprise me that much. It's hard for me to imagine getting 12 bits on something monolithic with a micro. I mentioned in my original post (perhaps you didn't see it) that 10.5 bits would be enough. I use integration, so if the noise is essentially gaussian I may be able to deal with this, satisfactorily. If not, could be an issue. I'll read up and thanks for the pointers! Jon
Reply by ●February 12, 20092009-02-12
On Feb 12, 7:05=A0pm, Jon Kirwan <j...@infinitefactors.org> wrote:> On Thu, 12 Feb 2009 02:30:25 -0800 (PST), korenje > ..... > >Be vary, that F28xx (including the picolo family) internal ADC does > >not deliver the promised 12 bits. Event the TI acknowledge this and > >state thet the ENOB is around 10 bits (that was for the first members > >of the family the F2812). > .... that 10.5 bits would be > enough. I use integration, so if the noise is essentially gaussian I > may be able to deal with this, satisfactorily. =A0If not, could be an > issue. =A0I'll read up and thanks for the pointers!Gaussian noise is the least likely issue they have. Most if not all of the 12 bit ADCs I have seen on MCUs are in reality more like 10 bits, INL is just that bad (DNL is 12-bittish, they have no missing codes after all). Please keep us posted if you find a true 12bit/1MSPS ADC on MCU, this would be something worth seeing. Dimiter ------------------------------------------------------ Dimiter Popoff Transgalactic Instruments http://www.tgi-sci.com ------------------------------------------------------ http://www.flickr.com/photos/didi_tgi/sets/72157600228621276/ Original message: http://groups.google.com/group/comp.arch.embedded/msg/25a= 210fc78417310?dmode=3Dsource
Reply by ●February 12, 20092009-02-12
On Thu, 12 Feb 2009 02:30:25 -0800 (PST), korenje <korenje@yahoo.co.uk> wrote:><snip> >The TI improves the ADC module each generation, but I can not tell you >how the picolo series ADC behavesI took a quick look. The gain error is +- 10 bits. But in this application, the algorithms are intentionally designed to perform compuations that remove gain as a factor. So long as the signal is in the conversion window, the gain is pretty much irrelevant (cancels out as a factor in the equations); so long as it doesn't vary over time during the snapshot, I'm fine. And I'm not looking at sine waves. I don't find a specification of internal noise -- magnitude, shape, etc. Nothing. There is some talk in the manual about SINAD and ENOB, but no data on input referred noise at various source voltages or S-N or distortion (the SINAD figure.) I've been using converters with about 11.3 ENOB in the past (about 70dB SINAD), but could live with 10.5 (about 65dB SINAD), I think. Do you know of any discussions that attempt to bound this figure for the Piccolo 2802x? Jon
Reply by ●February 12, 20092009-02-12
-jg wrote:> Jon Kirwan wrote: > >> I'm just getting into a project which "prefers" the ARM7 for business >> reasons, not technical ones. I do _not_ have experience writing for >> the ARM7 beyond some modest playing around, but will muddle through >> that part when the time comes. >> >> I'm looking for an ARM7TDMI core (or upward compatible) that includes >> a monolithic (unless someone goes through all the trouble of >> wire-bonding in packaging for reasonable prices) 12-bit minimum width, >> 1.5MHz minimum rate ADC (10.5-bit or so realizable at 2MHz with 1-2V >> signals is fine.) >> Right now I'm just trying to compile a list for examination. So even >> things that are close (1MHz, for example) would be okay to include. >> I'll talk it over, later, to see what we may have to accept. > > 12 bits and Multi MHz is a stretch, > Analog devices have 12 bits and 1MHz, in ARM7. > > NXP have Cortex cores at 1MHz / 12 bits, and Atmel AT91SAM3 > seems to have slipped - I think that was 12 bits/ 1MSPS too > .. > Documents suggesting Q3/Q4 08 SAM3 samples, have not been correct, > and their newest ARM family guide, skips the SAM3 entirelyYou can also take a look at ST's STM32 family. It it CM3 with very interesting mix of peripherals. It also has multichannel 12-bit ADC @ 1MHz. (No 1.5MHz or more sampling rate tough, for what you are looking for.) ~ Ale�
Reply by ●February 12, 20092009-02-12
On Thu, 12 Feb 2009 09:31:46 -0800 (PST), Didi <dp@tgi-sci.com> wrote:>On Feb 12, 7:05�pm, Jon Kirwan <j...@infinitefactors.org> wrote: >> On Thu, 12 Feb 2009 02:30:25 -0800 (PST), korenje >> ..... >> >Be vary, that F28xx (including the picolo family) internal ADC does >> >not deliver the promised 12 bits. Event the TI acknowledge this and >> >state thet the ENOB is around 10 bits (that was for the first members >> >of the family the F2812). >> .... that 10.5 bits would be >> enough. I use integration, so if the noise is essentially gaussian I >> may be able to deal with this, satisfactorily. �If not, could be an >> issue. �I'll read up and thanks for the pointers! > >Gaussian noise is the least likely issue they have. Most if not all >of the 12 bit ADCs I have seen on MCUs are in reality more like 10 >bits, INL is just that bad (DNL is 12-bittish, they have no missing >codes after all).I see a specification on the data sheet (one of the very few things they actually talk about regarding the ADC) of DNL +- 1 bit, INL +- 2 bits. Did you look at the datasheet? (Not that it should be believed, but I'm just wondering where you came up with the "12-bittish" for this device.)>Please keep us posted if you find a true 12bit/1MSPS ADC on MCU, this >would be something worth seeing.If I'm lucky enough to find something interesting, I will. The XMEGA specification is entirely TBD. So there is absolutely no information on it, btw. Jon
Reply by ●February 12, 20092009-02-12
On Feb 12, 5:30 am, korenje <kore...@yahoo.co.uk> wrote:> On Feb 12, 9:46 am, Jon Kirwan <j...@infinitefactors.org> wrote: > > > > > On Wed, 11 Feb 2009 23:20:12 -0800 (PST), -jg > > > <Jim.Granvi...@gmail.com> wrote: > > >> I'm seeing towards $4. But then I won't really know until an order is > > >> placed. Can you say anything about the tool chains you've experienced > > >> for this device? Cost, support reponsiveness, etc. Alternative > > >> development tools you looked at but didn't actually wind up trying > > >> out? > > > >Not on this family yet, but I did like the look of the Peripheral mix, > > >so it is on our radar for future use... > > >. > > >Very fast ADC, and high resolution timers. > > > Yeah. I'm impressed. > > > >TI are pushing some low-cost stuff > > >Experimenter Kit w/ControlCARD I see in stock at Newark for ~$82, > > >Piccolo controlSTICK is a USB stick, for $40.50 > > > >so that would be an easy way to quickly try the latest tools ?. > > > I suppose so. I'm a little disappointed looking at Eclipse > > development tool costs for active development (not trial stuff.) > > That's kind of off my radar range, if I decide to go that way. Which > > means I need to dig a little deeper about tools. But yes, the device > > appears attractive to me and I definitely appreciate the pointer. I > > think I'd heard the name dropped here once or twice, but never took > > notice before. But my head is turned now. So I'll put a little > > effort into looking further. > > > Jon > > Be vary, that F28xx (including the picolo family) internal ADC does > not deliver the promised 12 bits. Event the TI acknowledge this and > state thet the ENOB is around 10 bits (that was for the first members > of the family the F2812). For more info on this take a look at > comp.dsp and comp.arch.embedded archives and TI forumhttps://community.ti.com/forums/t/3165.aspx > > The TI improves the ADC module each generation, but I can not tell you > how the picolo series ADC behavesThere are actually few ADC that give you the same number of effective bits as resolution. Any noise at all causes a loss of effective bits and every part has noise, even separate ADC chips. It is just a question of how many bit survive the journey through the chip. 10 ENoB is not at all bad for a low cost 12 bit ADC, especially in an MCU. If you need much better than that, you are unlikely to find it without using a higher bit resolution device. But as others have said, uncorrelated noise can be averaged out... *if* it is uncorrelated. It is common for the noise to be related to the clock. After all, the same master clock is driving the MCU and the ADC. Rick
Reply by ●February 12, 20092009-02-12
Jon Kirwan <jonk@infinitefactors.org> writes:> I'm just getting into a project which "prefers" the ARM7 for business > reasons, not technical ones. I do _not_ have experience writing for > the ARM7 beyond some modest playing around, but will muddle through > that part when the time comes. > > I'm looking for an ARM7TDMI core (or upward compatible) that includes > a monolithic (unless someone goes through all the trouble of > wire-bonding in packaging for reasonable prices) 12-bit minimum width, > 1.5MHz minimum rate ADC (10.5-bit or so realizable at 2MHz with 1-2V > signals is fine.) Pipelined sampling and conversion stages is okay to > get the speed, as only one signal needs to be measured. Flash > programming of code, 1000-5000 pc qtys. Other features are far less > important, but RAM should be at least 2k (4k would be safer) and flash > should be at least 32k-64k (128k would probably be massive overkill.) > I/O required is probably less then 20 I/O pins (12, I'm counting right > now, outside the ADC input.) So a 44-pin package is well more than I > need. > > There is a core algorithm involved that processes the data, but to be > honest I don't need a blazingly fast cpu here -- the core parts that > require very fast speed will be written in assembly. I won't be using > floating point, except for a few custom routines I'll write. A fully > combinatorial barrel shifter with the ability to find the leading bit > and record the number of shifts required is a plus, though. I already > know that division is an issue for the ARM7 (software), but that is > okay as I keep division to a minimum, using wider 'registers' and > multiplicative sums and tracking divisors, holding the division parts > till the very end. > > I've seen a few cases with fancy debug trace buffers available over > JTAG and that would be "high cotton" if I could find that, together > with the ADC. But it really isn't necessary. > > The main thing I'm looking for a fast, decent 12-bit or better ADC > inside an ARM7TDMI (or upward compatible) cpu. The 1.5MHz minimum > requirement is a bit of a stretch, perhaps. But it is important and > I'm currently using an external ADC for this (which easily reach much > higher than this and with decent bits.) Pushing towards 2-3MHz would > be pure ecstasy. > > Right now I'm just trying to compile a list for examination. So even > things that are close (1MHz, for example) would be okay to include. > I'll talk it over, later, to see what we may have to accept.The ADUC7k family has a 12 bit, 1MHz ADC (as you probably know). It seems pretty good for an "embedded" ADC. As one might expect from an ADC manufacturer. It does in fact work at 2MHz if you set the clock divider bits appropriately, but to what extent that violates the spec I don't know. (I tried it just for fun once, and seemed to work fine!).> The other option is to use a non-ARM7TDMI compatible cpu, if that is > the only way to get there (for example, Atmel's XMEGA.) I'm hoping > there are some options in the ARM7 field, though. > > Thanks very much in advance for any suggestions to add to the list. > > Jon-- John Devereux
Reply by ●February 12, 20092009-02-12
On Thu, 12 Feb 2009 10:19:14 -0800 (PST), rickman <gnuarm@gmail.com> wrote:>On Feb 12, 5:30 am, korenje <kore...@yahoo.co.uk> wrote: >> On Feb 12, 9:46 am, Jon Kirwan <j...@infinitefactors.org> wrote: >> >> >> >> > On Wed, 11 Feb 2009 23:20:12 -0800 (PST), -jg >> >> > <Jim.Granvi...@gmail.com> wrote: >> > >> I'm seeing towards $4. But then I won't really know until an order is >> > >> placed. Can you say anything about the tool chains you've experienced >> > >> for this device? Cost, support reponsiveness, etc. Alternative >> > >> development tools you looked at but didn't actually wind up trying >> > >> out? >> >> > >Not on this family yet, but I did like the look of the Peripheral mix, >> > >so it is on our radar for future use... >> > >. >> > >Very fast ADC, and high resolution timers. >> >> > Yeah. I'm impressed. >> >> > >TI are pushing some low-cost stuff >> > >Experimenter Kit w/ControlCARD I see in stock at Newark for ~$82, >> > >Piccolo controlSTICK is a USB stick, for $40.50 >> >> > >so that would be an easy way to quickly try the latest tools ?. >> >> > I suppose so. I'm a little disappointed looking at Eclipse >> > development tool costs for active development (not trial stuff.) >> > That's kind of off my radar range, if I decide to go that way. Which >> > means I need to dig a little deeper about tools. But yes, the device >> > appears attractive to me and I definitely appreciate the pointer. I >> > think I'd heard the name dropped here once or twice, but never took >> > notice before. But my head is turned now. So I'll put a little >> > effort into looking further. >> >> > Jon >> >> Be vary, that F28xx (including the picolo family) internal ADC does >> not deliver the promised 12 bits. Event the TI acknowledge this and >> state thet the ENOB is around 10 bits (that was for the first members >> of the family the F2812). For more info on this take a look at >> comp.dsp and comp.arch.embedded archives and TI forumhttps://community.ti.com/forums/t/3165.aspx >> >> The TI improves the ADC module each generation, but I can not tell you >> how the picolo series ADC behaves > >There are actually few ADC that give you the same number of effective >bits as resolution.I never imagined differently. Resolution is almost a waste to care about. The only thing it does is provide a __suggestion__ about the care they took in designing it.>Any noise at all causes a loss of effective bits >and every part has noise, even separate ADC chips.I know.>It is just a >question of how many bit survive the journey through the chip. 10 >ENoB is not at all bad for a low cost 12 bit ADC, especially in an >MCU.I know that isn't bad. In fact, as I mentioned earlier, my expectations are only for about 10.5 bits ENOB, 65dB SINAD. I'm not expecting the impossible here. Just something that isn't garbage.>If you need much better than that, you are unlikely to find it >without using a higher bit resolution device.Which, obviously, would mean "slower" when talking about monolithic designs with the microcontroller. It's the combination of speed and ENOB that I'm looking for in a monolithic design and frankly I think it isn't entirely out of the ballpark. It's a doable, not unreasoned goal I'm looking for.>But as others have said, uncorrelated noise can be averaged out...Obviously. Gaussian distribution (integral of Poisson) is the assumption that goes into the very idea.>*if* it is uncorrelated.Of course. Correlated noise violates the assumption.>It is common for the noise to be related to the clock.Indeed.>After all, the same master clock is driving the MCU and the ADC.I know. I might expect this kind of lecture had I asked for something crazy. I didn't. Perhaps someone else learned something, though. Jon
Reply by ●February 12, 20092009-02-12
On Feb 12, 8:19=A0pm, Jon Kirwan <j...@infinitefactors.org> wrote:> On Thu, 12 Feb 2009 09:31:46 -0800 (PST), Didi <d...@tgi-sci.com> wrote: > >On Feb 12, 7:05=A0pm, Jon Kirwan <j...@infinitefactors.org> wrote: > >> On Thu, 12 Feb 2009 02:30:25 -0800 (PST), korenje > >> ..... > >> >Be vary, that F28xx (including the picolo family) internal ADC does > >> >not deliver the promised 12 bits. Event the TI acknowledge this and > >> >state thet the ENOB is around 10 bits (that was for the first members > >> >of the family the F2812). > >> .... that 10.5 bits would be > >> enough. I use integration, so if the noise is essentially gaussian I > >> may be able to deal with this, satisfactorily. =A0If not, could be an > >> issue. =A0I'll read up and thanks for the pointers! > > >Gaussian noise is the least likely issue they have. =A0Most if not all > >of the 12 bit ADCs I have seen on MCUs are in reality more like 10 > >bits, INL is just that bad (DNL is 12-bittish, they have no missing > >codes after all). > > I see a specification on the data sheet (one of the very few things > they actually talk about regarding the ADC) of DNL +- 1 bit, INL +- 2 > bits. =A0Did you look at the datasheet? =A0(Not that it should be > believed, but I'm just wondering where you came up with the > "12-bittish" for this device.)No, this is just my general experience with ADCs speaking. I have looked through a fair number of MCU ADCs, and I do not remember having seen one like the one you describe, that's all. If they specify INL as +/- 2 *bits*, not LSBs, this might be reason to raise some suspicion. It may mean the 2 lowest bits are meaningless, which will match my observation on MCU ADCs lately. IIRC I saw one - I think on some Microchip part I was reviewing for someone - which was true 12 bit or sort of, but was much much slower (double integrating IIRC). I have been spoilt by ADI when it comes to ADCs, I guess, but I know only their standalone ones (their specs are really trustworthy). Dimiter ------------------------------------------------------ Dimiter Popoff Transgalactic Instruments http://www.tgi-sci.com ------------------------------------------------------ http://www.flickr.com/photos/didi_tgi/sets/72157600228621276/ Original message: http://groups.google.com/group/comp.arch.embedded/msg/d46= c90be2743ff2b?dmode=3Dsource
