Forums

Your Favorite ARM?

Started by Martin Riddle December 26, 2011
On 12/26/2011 7:35 PM, jw@myplace.com wrote:
> On Mon, 26 Dec 2011 20:19:27 -0500, "Martin Riddle" > <martin_rid@verizon.net> wrote: > >> Which Mfg has the best options for their ARM processors? >> I've never worked with a ARM, and I was going to play with a Atmel >> AVR32, but the ARM seems to have more features for a buck or two more. >> Preferable package is LQFP. And not so pricey tools. >> 12 bit DAC and ADC a plus. >> >> Cheers >> >> > Waht is an ARM? (Dont say the thing attached to my shoulder :) ). >
Advanced Reduced instruction set Microcontroller.
On Mon, 26 Dec 2011 18:57:49 -0800, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

>On Mon, 26 Dec 2011 20:19:27 -0500, "Martin Riddle" ><martin_rid@verizon.net> wrote: > >>Which Mfg has the best options for their ARM processors? >>I've never worked with a ARM, and I was going to play with a Atmel >>AVR32, but the ARM seems to have more features for a buck or two more. >>Preferable package is LQFP. And not so pricey tools. >>12 bit DAC and ADC a plus. >> >>Cheers >> >> >> > >Depends on how much horespower you need. We have one board with a >dozen LPC1754s on board, and they work fine. It has a 12-bit ADC and a >10-bit DAC, on-chip flash and ram, 100 MHz. We pay about $3.50 each >for them, programmed by Arrow with our code. > >The 12-bit ADC is accurate to 9 bits maybe. We wound up doing a curve >fit to every one at cal time, to get it to 0.1%. uP ADCs tend to be >like that. > >We also use a bunch of LPC3250s, much more serious parts: BGA, vector >floating point, DRAM controller, 260 MHz or so, about $7.50. > >The NXP LPCs are OK, but the manuals are sort of pitiful. > >John >
Interesting ! We use NXP LPC176x and LPC2366 parts and I like them. I was going to do some kind of A/D calibration tables to help the 10 bit converters. Do you do a 1:1 (4096 point) table mapping or do you just do a limited amount of points and interpolate or something else ? How long does it take to calibrate one part in production and is it repeatable as far as drift etc out in the field ?? I would guess that maybe it is but how well does it really "stick" ?? How different is one part's A/D from another ? Are they all over the place ? boB K7IQ
[This followup was posted to sci.electronics.design and a copy was sent 
to the cited author.]

 article <5fcif792ljl9morgkae9kq27stpenoc5dj@4ax.com>, 
jjlarkin@highNOTlandTHIStechnologyPART.com says...
> > The 12-bit ADC is accurate to 9 bits maybe. We wound up doing a curve > fit to every one at cal time, to get it to 0.1%. uP ADCs tend to be > like that. >
Do you do that curve fit by piecewise linear interpolation? -- Michael Karas Carousel Design Solutions http://www.carousel-design.com
On 27 Dec 2011 02:07:00 -0600, boB wrote:

>On Mon, 26 Dec 2011 18:57:49 -0800, John Larkin ><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: > >>On Mon, 26 Dec 2011 20:19:27 -0500, "Martin Riddle" >><martin_rid@verizon.net> wrote: >> >>>Which Mfg has the best options for their ARM processors? >>>I've never worked with a ARM, and I was going to play with a Atmel >>>AVR32, but the ARM seems to have more features for a buck or two more. >>>Preferable package is LQFP. And not so pricey tools. >>>12 bit DAC and ADC a plus. >>> >>>Cheers >>> >>> >>> >> >>Depends on how much horespower you need. We have one board with a >>dozen LPC1754s on board, and they work fine. It has a 12-bit ADC and a >>10-bit DAC, on-chip flash and ram, 100 MHz. We pay about $3.50 each >>for them, programmed by Arrow with our code. >> >>The 12-bit ADC is accurate to 9 bits maybe. We wound up doing a curve >>fit to every one at cal time, to get it to 0.1%. uP ADCs tend to be >>like that. >> >>We also use a bunch of LPC3250s, much more serious parts: BGA, vector >>floating point, DRAM controller, 260 MHz or so, about $7.50. >> >>The NXP LPCs are OK, but the manuals are sort of pitiful. >> >>John >> > >Interesting ! > >We use NXP LPC176x and LPC2366 parts and I like them. >I was going to do some kind of A/D calibration tables to help the 10 >bit converters. > >Do you do a 1:1 (4096 point) table mapping or do you just do a >limited amount of points and interpolate or something else ?
On the board I mentioned, we did a 64-point lookup table with interpolation. The ADC transfer function had some jumps, so that was good. Sometimes we do polynomials for stuff like this, if the curves are softer.
> >How long does it take to calibrate one part in production
I recall times like 20 minutes to test/cal a board, all automated. This is it: http://www.highlandtechnology.com/DSS/V220DS.shtml The uPs are each electrically isolated and each one runs a local PID loop to do each 4-20 mA channel. Sort of a nuisance to design. and is it
>repeatable as far as drift etc out in the field ??
I sure hope so! Seems OK so far. But I guess asking a uP ADC to do 0.1% is pushing things. I would guess
>that maybe it is but how well does it really "stick" ?? How different >is one part's A/D from another ? Are they all over the place ?
Enough that we can't spec 0.1% without a lookup table for each one. The cal table also picks up all the resistor tolerances, opamp offsets, whatever, so it's all lumped together. In retrospect, we could have used a real ADC, ADS7866 maybe, and saved a lot of hassle. John
On Tue, 27 Dec 2011 06:28:05 -0800, Michael Karas
<mkaras@carousel-design.com> wrote:

>[This followup was posted to sci.electronics.design and a copy was sent >to the cited author.] > > article <5fcif792ljl9morgkae9kq27stpenoc5dj@4ax.com>, >jjlarkin@highNOTlandTHIStechnologyPART.com says... >> >> The 12-bit ADC is accurate to 9 bits maybe. We wound up doing a curve >> fit to every one at cal time, to get it to 0.1%. uP ADCs tend to be >> like that. >> > >Do you do that curve fit by piecewise linear interpolation?
Yes, 64-point lookup table. John
On 27/12/11 11:36, Martin Riddle wrote:
> "John Larkin"<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in > message news:5fcif792ljl9morgkae9kq27stpenoc5dj@4ax.com... >> On Mon, 26 Dec 2011 20:19:27 -0500, "Martin Riddle" >> <martin_rid@verizon.net> wrote: >> >>> Which Mfg has the best options for their ARM processors? >>> I've never worked with a ARM, and I was going to play with a Atmel >>> AVR32, but the ARM seems to have more features for a buck or two more. >>> Preferable package is LQFP. And not so pricey tools. >>> 12 bit DAC and ADC a plus. >>> >>> Cheers >>> >>> >>> >> >> Depends on how much horespower you need. We have one board with a >> dozen LPC1754s on board, and they work fine. It has a 12-bit ADC and a >> 10-bit DAC, on-chip flash and ram, 100 MHz. We pay about $3.50 each >> for them, programmed by Arrow with our code. >> >> The 12-bit ADC is accurate to 9 bits maybe. We wound up doing a curve >> fit to every one at cal time, to get it to 0.1%. uP ADCs tend to be >> like that. >> >> We also use a bunch of LPC3250s, much more serious parts: BGA, vector >> floating point, DRAM controller, 260 MHz or so, about $7.50. >> >> The NXP LPCs are OK, but the manuals are sort of pitiful. >> >> John >> >> > > Ok, I can live with that. I never seen really good performance from on > board ADC's anyway, always some errata associated with them. DAC's were > always external. > The LPC17xx looks like it would fit the bill. Even has a Ethernet which > I will need. > This must be ARMv7 = Cortex-M3... > > Ok, I'm off to find a demo board. > > Thanks! > > Cheers
Before you run off consider this one: http://search.digikey.com/hk/en/products/STM32F4DISCOVERY/497-11455-ND/2711743 The eval board costs roughly the same as a chip, about 20 USD. Cortex M4 with floating point (and potentially ethernet). Really sexy!
On Dec 27, 10:52=A0am, Werner <wd...@netfront.net> wrote:
> On 27/12/11 11:36, Martin Riddle wrote: > > > > > > > > > "John Larkin"<jjlar...@highNOTlandTHIStechnologyPART.com> =A0wrote in > > messagenews:5fcif792ljl9morgkae9kq27stpenoc5dj@4ax.com... > >> On Mon, 26 Dec 2011 20:19:27 -0500, "Martin Riddle" > >> <martin_...@verizon.net> =A0wrote: > > >>> Which Mfg has the best options for their ARM processors? > >>> I've never worked with a ARM, and I was going to play with a Atmel > >>> AVR32, but the ARM seems to have more features for a buck or two more=
.
> >>> Preferable package is LQFP. =A0And not so pricey tools. > >>> 12 bit DAC and ADC a plus. > > >>> Cheers > > >> Depends on how much horespower you need. We have one board with a > >> dozen LPC1754s on board, and they work fine. It has a 12-bit ADC and a > >> 10-bit DAC, on-chip flash and ram, 100 MHz. We pay about $3.50 each > >> for them, programmed by Arrow with our code. > > >> The 12-bit ADC is accurate to 9 bits maybe. We wound up doing a curve > >> fit to every one at cal time, to get it to 0.1%. uP ADCs tend to be > >> like that. > > >> We also use a bunch of LPC3250s, much more serious parts: BGA, vector > >> floating point, DRAM controller, 260 MHz or so, about $7.50. > > >> The NXP LPCs are OK, but the manuals are sort of pitiful. > > >> John > > > Ok, I can live with that. I never seen really good performance from on > > board ADC's anyway, always some errata associated with them. DAC's were > > always external. > > The LPC17xx looks like it would fit the bill. Even has a Ethernet which > > I will need. > > This must be ARMv7 =3D Cortex-M3... > > > Ok, I'm off to find a demo board. > > > Thanks! > > > Cheers > > Before you run off consider this one: > > http://search.digikey.com/hk/en/products/STM32F4DISCOVERY/497-11455-N... > > The eval board costs roughly the same as a chip, about 20 USD.
Really? I read $165.79 with your link. There are probably cheaper version.
On 28/12/11 03:05, linnix wrote:
> On Dec 27, 10:52 am, Werner<wd...@netfront.net> wrote: >> On 27/12/11 11:36, Martin Riddle wrote: >> >> >> >> >> >> >> >>> "John Larkin"<jjlar...@highNOTlandTHIStechnologyPART.com> wrote in >>> messagenews:5fcif792ljl9morgkae9kq27stpenoc5dj@4ax.com... >>>> On Mon, 26 Dec 2011 20:19:27 -0500, "Martin Riddle" >>>> <martin_...@verizon.net> wrote: >> >>>>> Which Mfg has the best options for their ARM processors? >>>>> I've never worked with a ARM, and I was going to play with a Atmel >>>>> AVR32, but the ARM seems to have more features for a buck or two more. >>>>> Preferable package is LQFP. And not so pricey tools. >>>>> 12 bit DAC and ADC a plus. >> >>>>> Cheers >> >>>> Depends on how much horespower you need. We have one board with a >>>> dozen LPC1754s on board, and they work fine. It has a 12-bit ADC and a >>>> 10-bit DAC, on-chip flash and ram, 100 MHz. We pay about $3.50 each >>>> for them, programmed by Arrow with our code. >> >>>> The 12-bit ADC is accurate to 9 bits maybe. We wound up doing a curve >>>> fit to every one at cal time, to get it to 0.1%. uP ADCs tend to be >>>> like that. >> >>>> We also use a bunch of LPC3250s, much more serious parts: BGA, vector >>>> floating point, DRAM controller, 260 MHz or so, about $7.50. >> >>>> The NXP LPCs are OK, but the manuals are sort of pitiful. >> >>>> John >> >>> Ok, I can live with that. I never seen really good performance from on >>> board ADC's anyway, always some errata associated with them. DAC's were >>> always external. >>> The LPC17xx looks like it would fit the bill. Even has a Ethernet which >>> I will need. >>> This must be ARMv7 = Cortex-M3... >> >>> Ok, I'm off to find a demo board. >> >>> Thanks! >> >>> Cheers >> >> Before you run off consider this one: >> >> http://search.digikey.com/hk/en/products/STM32F4DISCOVERY/497-11455-N... >> >> The eval board costs roughly the same as a chip, about 20 USD. > > Really? I read $165.79 with your link. There are probably cheaper > version.
What you see there is HK Dollars. It's roughly 8:1. The US page is here: http://search.digikey.com/us/en/products/STM32F4DISCOVERY/497-11455-ND/2711743 I just noticed they ran out of stock, Mouser still has them, at 16.25$: http://hk.mouser.com/ProductDetail/STMicroelectronics/STM32F4DISCOVERY/?qs=sGAEpiMZZMutVogd4PRSvEN8XDBeCtgD They gave these away for free as handouts at a seminar a couple of months ago. There is also a discovery board for STM32F1xx Cortex M3 for 12 US$. http://tinyurl.com/7gjolpo Regards Werner
On Tue, 27 Dec 2011 11:05:49 -0800 (PST), the renowned linnix
<me@linnix.info-for.us> wrote:

>On Dec 27, 10:52&#2013266080;am, Werner <wd...@netfront.net> wrote: >> On 27/12/11 11:36, Martin Riddle wrote: >> >> >> >> >> >> >> >> > "John Larkin"<jjlar...@highNOTlandTHIStechnologyPART.com> &#2013266080;wrote in >> > messagenews:5fcif792ljl9morgkae9kq27stpenoc5dj@4ax.com... >> >> On Mon, 26 Dec 2011 20:19:27 -0500, "Martin Riddle" >> >> <martin_...@verizon.net> &#2013266080;wrote: >> >> >>> Which Mfg has the best options for their ARM processors? >> >>> I've never worked with a ARM, and I was going to play with a Atmel >> >>> AVR32, but the ARM seems to have more features for a buck or two more. >> >>> Preferable package is LQFP. &#2013266080;And not so pricey tools. >> >>> 12 bit DAC and ADC a plus. >> >> >>> Cheers >> >> >> Depends on how much horespower you need. We have one board with a >> >> dozen LPC1754s on board, and they work fine. It has a 12-bit ADC and a >> >> 10-bit DAC, on-chip flash and ram, 100 MHz. We pay about $3.50 each >> >> for them, programmed by Arrow with our code. >> >> >> The 12-bit ADC is accurate to 9 bits maybe. We wound up doing a curve >> >> fit to every one at cal time, to get it to 0.1%. uP ADCs tend to be >> >> like that. >> >> >> We also use a bunch of LPC3250s, much more serious parts: BGA, vector >> >> floating point, DRAM controller, 260 MHz or so, about $7.50. >> >> >> The NXP LPCs are OK, but the manuals are sort of pitiful. >> >> >> John >> >> > Ok, I can live with that. I never seen really good performance from on >> > board ADC's anyway, always some errata associated with them. DAC's were >> > always external. >> > The LPC17xx looks like it would fit the bill. Even has a Ethernet which >> > I will need. >> > This must be ARMv7 = Cortex-M3... >> >> > Ok, I'm off to find a demo board. >> >> > Thanks! >> >> > Cheers >> >> Before you run off consider this one: >> >> http://search.digikey.com/hk/en/products/STM32F4DISCOVERY/497-11455-N... >> >> The eval board costs roughly the same as a chip, about 20 USD. > >Really? I read $165.79 with your link. There are probably cheaper >version.
<ahem> Do you know the difference between HKD and USD? (it's been pegged at about 7.8 to the USD for going on 30 years, though surely they will scrap the outdated USD peg and change to the CNY pretty soon). Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
On Dec 27, 12:01=A0pm, Spehro Pefhany
<speffS...@interlogDOTyou.knowwhat> wrote:
> On Tue, 27 Dec 2011 11:05:49 -0800 (PST), the renowned linnix > > > > > > > > > > <m...@linnix.info-for.us> wrote: > >On Dec 27, 10:52=A0am, Werner <wd...@netfront.net> wrote: > >> On 27/12/11 11:36, Martin Riddle wrote: > > >> > "John Larkin"<jjlar...@highNOTlandTHIStechnologyPART.com> =A0wrote i=
n
> >> > messagenews:5fcif792ljl9morgkae9kq27stpenoc5dj@4ax.com... > >> >> On Mon, 26 Dec 2011 20:19:27 -0500, "Martin Riddle" > >> >> <martin_...@verizon.net> =A0wrote: > > >> >>> Which Mfg has the best options for their ARM processors? > >> >>> I've never worked with a ARM, and I was going to play with a Atmel > >> >>> AVR32, but the ARM seems to have more features for a buck or two m=
ore.
> >> >>> Preferable package is LQFP. =A0And not so pricey tools. > >> >>> 12 bit DAC and ADC a plus. > > >> >>> Cheers > > >> >> Depends on how much horespower you need. We have one board with a > >> >> dozen LPC1754s on board, and they work fine. It has a 12-bit ADC an=
d a
> >> >> 10-bit DAC, on-chip flash and ram, 100 MHz. We pay about $3.50 each > >> >> for them, programmed by Arrow with our code. > > >> >> The 12-bit ADC is accurate to 9 bits maybe. We wound up doing a cur=
ve
> >> >> fit to every one at cal time, to get it to 0.1%. uP ADCs tend to be > >> >> like that. > > >> >> We also use a bunch of LPC3250s, much more serious parts: BGA, vect=
or
> >> >> floating point, DRAM controller, 260 MHz or so, about $7.50. > > >> >> The NXP LPCs are OK, but the manuals are sort of pitiful. > > >> >> John > > >> > Ok, I can live with that. I never seen really good performance from =
on
> >> > board ADC's anyway, always some errata associated with them. DAC's w=
ere
> >> > always external. > >> > The LPC17xx looks like it would fit the bill. Even has a Ethernet wh=
ich
> >> > I will need. > >> > This must be ARMv7 =3D Cortex-M3... > > >> > Ok, I'm off to find a demo board. > > >> > Thanks! > > >> > Cheers > > >> Before you run off consider this one: > > >>http://search.digikey.com/hk/en/products/STM32F4DISCOVERY/497-11455-N..=
.
> > >> The eval board costs roughly the same as a chip, about 20 USD. > > >Really? =A0I read $165.79 with your link. =A0There are probably cheaper > >version. > > <ahem> Do you know the difference between HKD and USD? =A0(it's been > pegged at about 7.8 to the USD for going on 30 years, though surely > they will scrap the outdated USD peg and change to the CNY pretty > soon).
Yes, of course. I just didn't see it. In fact, i still have a few hundred HKD and Yuen around somewhere.