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Re: Micro with 4-independent PWM channels

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Is it just me, or is this getting to sound like a vendor forum?

--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer:  Electronics; Informatics; Photonics.
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Re: Micro with 4-independent PWM channels

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I'd be happy if MORE vendors frequented the group.

I don't see anything wrong, and much right, for a knowledgeable
manufacturer's rep to post an on-topic reply to an open question like
this.

--
Rich Webb   Norfolk, VA

Re: Micro with 4-independent PWM channels
Hi Rich,

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Exactly! I think it is great that Ulf is here for Atmel and I'd hope
Texas Instruments, Microchip, Philips and others would also see the
benefits of a close-up contact with their customer base. Or with
potential customers. After all, we are the folks who are rendering
pretty final decisions about which products are being released and which
ones are not. Fact is, once a part is released it is next to impossible
for another manufacturer to get a foot in the door unless they have a
100% compatible device. Except for the 8051 world that isn't generally
possible for micro controllers.

Ulf, you can quote me on that if it helps with your bosses.

Regards, Joerg

http://www.analogconsultants.com

Re: Micro with 4-independent PWM channels
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Atmel sells the 8051 as well, but that does not mean I have to like it
privately.
I do this mostly on  my free time and had to fight to even get access to
the newsgroups at Atmel. I doubt that anyone in my management is
even aware that the Newsgroups exist.

Just happen to like the AVR, and think that most other people willl, if they
try it!

Even when I worked at National Semiconductor in 1995-6, I recommended them
to license the AVR
(and to start building general purpose micros based on the ARM7).

They licensed the ARM7TDMI (actually ARM designed
the synthesizable ARMTDMI-S on Nationals request) and the University
of Michigan designed a CPU very similar to the AVR for National
but the microcontroller group there is dysfunctional and decided to
continure
with the COP8 and went ahead with the CR16 (even of the 32 bit CR32
would have been better)

The CR16/32  is not to bad, but totally wrong focus from the wrong company
has more or less killed the part.

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Re: Micro with 4-independent PWM channels
Hi,

a significantly better device than the AT91SAM.. would be the Philips
LPC2131.
It is fast, gives you much more I/O pins and a growth path if needed up
to 512K flash.
Boards are already available from Keil or LPCtools.com.  The 32k IAR
compiler applies as it does with the Atmel device.

An Schwob

Ulf Samuelsson wrote:
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of
interrupts,C-Compiler
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of


Re: Micro with 4-independent PWM channels
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LPC2131.
512K flash.

The LPC2xxx parts are interesting devices, and compared to the SAM7 parts
they have both strengths and weaknesses.

The speed of the part is depending on the mode.
The SAM7 uses a 32 bit bus running at 30 MHz
the LPC part uses a 128 bit bus running at 20 MHz

This makes the LPC the best part for fetching 32 bit ARM code (3 + 1 + 1 + 1
= 6 clocks).
I ghuess it will satrt to prefetch, so for additional accesses it is 1+1+1+1
= 4 clocks.
The SAM7 will use (2+2+2+2 = 8 clocks) in ARM mode.
Whenever there is a datafetch from flash,
the SAM7 will use 2 clocks and the LPC will use 3 clocks and
It is not clear to me, if that flushes the instruction buffer.
There is a mode to buffer dataaccesses as well so sequential accesses are
fast.


For 16 bit Thumb mode, the SAM7 has an advantage
since it can fetch the first access in 2 clocks where the LPC will need 3
clocks
The SAM7 will then fetch 2 instructions at the time so
it will use (2+1+1+1+...) úntil a jump,. while the LPC uses 3+1+1+1
and for datafetches, the 2 clcok cycle accesse makes the SAM7 faster
unless sequential datareads are performed.

ARM mode is about 12 % faster than Thumb mode, but use 30 % more code.

If you use the ARM mode, then I think the LPC should be faster
but if you run in Thumb mode, as many do, then the SAM7 is slightly faster.

If you have a small critical loop in ARM mode, then you can copy that into
SRAM
and run 32 bit zero waitstate.

The big disadvantage of the 128 bit memory access is that the LPC
has 2 x  the core power consumption of the SAM7 series.

The DMA of the SAM7 serial peripherals are pretty useful if you
want to run at high speed and if you compare the throughput of the
two parts then peripherals have to be taken into account.
At least the earliest LPC devices .had problem toggling I/O.
I heard 1 Mhz or so, but users may be able to provide more detailed info
The SAM/ can toggle I/O at 5 - 6 MHz, and the SPI runs at 55 Mhz.
allowing about 5-6 MByte per second download from dataflash.


As for I/O,  Atmel is more conservative on power pads having 14 instead
of the Philips 9. There is also a 1.8V regulator output which could be
useful
for other parts of the system.
You lose the JTAG on some of the parts, and the SAM7 has a special interface
for speeding up production programming. Have not seen any ciomparision of
programming time for the different devices, so I have no clue whether
this makes sense or not.

The biggest selling point at the moment is probably the onchip USB.

In the end, I think that both companies will be in strong competion and
emulate the successful features of the other party, making the 32 bit ARM
micros a very attractive proposition over some competing 8/16 bitters.

/Ulf

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Re: Micro with 4-independent PWM channels
Hi Ulf,

guess you forgot something about the clocks. While Philips seems top be
more conservative about the flash access time, specofying it with
approx 50 ns access time over temperature, Atmel claims 33 ns quite
good.
Now about the cycles.  While Philips might need a clock cycle more at
60 MHz compared to a SAM7 at 30 MHZ to execute the first instruction
after a branch that leaves it still a lot faster. SAM7 has the max
throughput @ 30 MHz, LPC2000 @ 60 MHz. The cycles you mentioned are
clock cycles not bus cycles ;-)

We tested the port switching and because the ports are connected to the
peripheral bus the limit is 4 MHz while Atmel can do a little more than
5 MHz connected to the AHB.  Point taken and accepted. Unfortunately
you have to run the SAM7 with wait states when doing that. Running at
30 MHz which provides max. performance and best power / performance
ratio gives you even less than 4 MHz switch frequency.

According to a Philips presentation on the ARM developers conference
there is a Data Bypass Buffer for data fetched from flash, it does not
interfere with the instruction pipeline.

The presentations I have seem from Atmel state a power consumption of
approximately 50 mA @ 50 MHz, the measurement we did with the LPC2131
showed 43 mA @ 60 MHz, giving twice the performance at less power, I
have no idea where you got your power numbers from.  To be fair, we did
not measure the SAM7 yet because the performance is just not enough for
what we are doing.

USB is a good point for the Atmel devices, but the SAM7S32 does not
have one or did I miss something?  The S64 pricing announced at the ARM
devcon was 50% higher than that of the S32! USB comes at a price and
with some delay.  Looking forward to the Philips USB devices as well.

May be Philips uses a lower power process? because I would have
expected the SAM7 to be lower power given the performance difference.

In the end we totally agree that both companies will be strong
competitors and the ARM micros are highly competitive against high end
8-bit and the full range of 16-bit micros.

btw. although we might somewhat disagree which devices to use I really
appreciate your postings because you try very hard and successfully to
stay on a technical level.


Re: Micro with 4-independent PWM channels
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At room temp, the SAM7 runs zero waitstate at 48 MHz.


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In Thumb mode, your highest throughput is when you run it in max frequency
or 55 MHz.

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55 MHz from SRAM is faster and if you really need toggle speed, then there
is the SPI and SSCs.
Don't think the SSC is present on the LPC.

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Datasheet says 29-30 mA on the VccCore when the CPU runs at 50 Mhz.
Philips datasheet states this a little higher than 43 mA IIRC.

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The S64 of course adds an additional 32 kB flash and 8 KB SRAM.

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I think that the presentation you have is wrong.

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--
Best Regards
Ulf at atmel dot com
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Re: Micro with 4-independent PWM channels

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The peripherals on the Philips devices are not even remotely as well
sorted out as they should be. Doing things such as : Cannot read the
state of an input pin if it has been defined as a capture input.
Ditto for defining a pin as an external interrrupt, and then of course
putting a PC compatable UART in the thing.

Regards
   Anton Erasmus




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Re: Micro with 4-independent PWM channels

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You could take a look at the Atmel ATmega128 which features two 16 bit
timers with each 3 PWM channels and a 8 bit timer with 2 PWM channels; 10
bit ADC, 128Mb of flash, 4K int RAM, runs at 16MHz max. and is C compiler
friendly.

Jeroen



Re: Micro with 4-independent PWM channels
On Sat, 22 Jan 2005 01:58:25 -0600, the renowned

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18F6520 is roughly within your price range, and has 5 independent
PWMs. You really need to search through the data sheets yourself to
optimize this sort of thing. I also suggest looking at the MSP430
series from TI.


Best regards,
Spehro Pefhany
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"it's the network..."                          "The Journey is the reward"
snipped-for-privacy@interlog.com             Info for manufacturers: http://www.trexon.com
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Re: Micro with 4-independent PWM channels
On Sat, 22 Jan 2005 11:24:24 -0500, Spehro Pefhany

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And at 10 bits.  Looks like it may be a fit.

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This one has particularly effective timers, with associated capture compares
that can be used for PWM.  It would be worth considering for the application,
too, I'd imagine.

Both good recommendations to start.

Jon

Re: Micro with 4-independent PWM channels

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The Philips LPC2131 (ARM7, 32KB Flash, 8KB RAM, 6 PWM, 8ch 10bit A/D etc.,
GCC C compiler) should fit.  Or LPC2132 if you need more flash and RAM and a
10bit DAC.

Regards,
Karl Olsen




Re: Micro with 4-independent PWM channels
Mike escreveu:
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You may add to the other suggestions the TI TMS320LF2401, but yuo'll
have a startup cost somewhat high (no free tools).

Ricardo

Re: Micro with 4-independent PWM channels

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..and another option, at the high end, would be the new
TMS470 ARM Flash uC from TI.
  From the info posted so far, it seems they have a
timer-control-engine, somewhat similar to the Motorola TPU, on their
timer channels.
  Has anyone used this ?

  Probably a tad overkill for 4 x 1KHz PWMs :)
-jg


Re: Micro with 4-independent PWM channels
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  Following up, I see a press release today
http://www.eeproductcenter.com/micro/review/showArticle.jhtml?articleID57%702943

that claims these are TMS470R1A64 @ $4.95/1K, and are available now, (so
that was a faster release ramp than some) ....
-jg


Re: Micro with 4-independent PWM channels
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Rabbit 3000A has 4 independent 10bit PWM, interrupts, and has C
support. You'll need an external A/D (it has hardware SPI) and
it's more than $6.00.

    http://rabbitsemiconductor.com/products/rab3000 /

See ya, -ingo
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