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
Take a look at Cypress' PSoC5. Looks pretty nice to me.
Cheers to you, too. John S
Forgot to mention that "PSoC Creator" is what you will use with it. It essentially allows you to draw a schematic and provides you with code to manage it.
John S
Waht is an ARM? (Dont say the thing attached to my shoulder :) ).
first ones that comes to mind is LPC and stm32f
there's gcc for ARM and they can be programmed with a serial port, usb and more so tools can be free
-Lasse
The one in your phone, most likely.
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
ST, TI, NXP all have various flavors of ARM and reasonable priced development boards. I have development boards from all three. I just finished a Cortex M3 design with a LPC1768 LQFP. Ethernet, CAN, SPI and a bunch of GPIO. You can get a LPCXpresso board from Mouser for 32 bucks and download the free (but limited) Code Red compiler suite. I switched to Eclipse and GNU cross compiler and OpenOCD for JTAG programming/debug.
Like I mentioned, TI and ST have similar offerings. Really depends on what you need. Ethernet? USB? A bunch of UARTS? How many channels for ADC?
-- Chisolm Republic of Texas
The erstwhile Luminary, now a part of Texas Instruments, Stellaris Cortex M3 parts are pretty nice too, esp. for their built-in ethernet PHY.
If you are serious about on-chip analog peripherals, you can look at relevant AD parts which contain pretty decent ADC/DAC converters and an ARM7TDMI (32 and 16 bit modes) as sort of a peripheral.
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
"John Larkin" wrote in message news: snipped-for-privacy@4ax.com...
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
Advanced Reduced instruction set Microcontroller.
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
Do you do that curve fit by piecewise linear interpolation?
-- Michael Karas Carousel Design Solutions http://www.carousel-design.com
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.
I recall times like 20 minutes to test/cal a board, all automated. This is it:
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
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
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
Yes, 64-point lookup table.
John
Before you run off consider this one:
The eval board costs roughly the same as a chip, about 20 USD. Cortex M4 with floating point (and potentially ethernet).
Really sexy!
.
Really? I read $165.79 with your link. There are probably cheaper version.
What you see there is HK Dollars. It's roughly 8:1. The US page is here:
They gave these away for free as handouts at a seminar a couple of months ago.
There is also a discovery board for STM32F1xx Cortex M3 for 12 US$.
Regards Werner
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
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.Yes, of course. I just didn't see it. In fact, i still have a few hundred HKD and Yuen around somewhere.
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