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The PIC32 can toggle an output pin at 72 MHz, unlike the LPC2000, giving a
36 MHz output.

Leon



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--- In l...@yahoogroups.com, "Leon" wrote:
>
> The PIC32 can toggle an output pin at 72 MHz, unlike the LPC2000,
giving a
> 36 MHz output.
>

?? So can a 36MHz xtal oscillator. Why would you use a PIC32 to
generate a fixed-frequency square wave? Would not such a chip be
better used for, say, controlling a washing-machine or toaster oven?

Rgds,
Martin



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stevech11 wrote:
>
> --- In lpc2000@yahoogroups .com ,
> "Paul Curtis" wrote:
> >
> > Hi,
> >
> > > Leon ha scritto:
> > > >
> > > > The PIC32 can toggle an output pin at 72 MHz, unlike the LPC2000,
> > > > giving a 36 MHz output.
> > > Many embedded microprocessors can be configured to toggle an I/O pin
> whenever a timer overflows. Thus, the speed of the CPU is unimportant.
>
> I have to say, this discussion about 72MHz I/O bit toggling is silly.
>

Gee, if I take a PIC and bang an D/A fast enough, I wouldn't need an
oscillator to transmit WiFi ! Just follow it with a mixer and RF Amp!

heh

TomW
--
Tom Walsh - WN3L - Embedded Systems Consultant
http://openhardware.net http://cyberiansoftware.com http://openzipit.org
"Windows? No thanks, I have work to do..."
----------------------------------------------------



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Paul Curtis ha scritto:
>
> Hi,
>
>> Leon ha scritto:
>>>
>>> The PIC32 can toggle an output pin at 72 MHz, unlike the LPC2000,
>>> giving a 36 MHz output.
>>
>> Is it an useful information? Why? Do you need to toggle an output
>> pin several times? Is this a mesaure of computing power? May you
>> explaining why are you writing this sentence?
>
> The point is not that the square wave *needs* to be generated, the
> point of the argument is how fast it *can* be generated, i.e. the
> latency of the core from the initial write to the port register to
> the pin being changed.
>
> Programmed I/O usually needs to be fairly fast, why else would
> Philips add Fast I/O to the newer LPCs other than by recognizing and
> responding to customer demand? Just go back through the archives of
> this group and look at the postings that say the older LPCs without
> fast I/O can't do programmed I/O faster than a SiLabs 8051. Anybody
> upgrading from a SiLabs 8-bitter with fast I/O to an allegedly faster
> ARM would question why they can't change output pins quickly.
>
Upgrading is not only an i/o matter, I am also working with old 8051
(only for project maintenance)
and they are slow not only for i/o. When AVRs born their advantage was
that 80% of instructions were executed in 1 cpu cycle and 1 cycle
wasn't made by 12 clock cycles as 8051 or 4 clock cycles as others (also
others as Dallas made fast 8051 without 1/12 instruction/clock rate).
So the engineer may choose the best cpu for its application. Surely in
LPC family the i/o speed wasn't fast, for my point of view it is
important to know WHEN an i/o pin switches on or off, taking care of
interrupt latency and o.s. latency (if you use one) and to have one or
more timers to toggle pins without using cpu instructions; especially in
applications where we have to deal with EMI, it is more comfortable if
there are few high speed i/o (those strictly necessary).
About Philips/NXP decision it is a marketing decision, LPC family it is
in mass production from few years, before LPC born Philips guys sold
millions of ARM cpus very similar to LPC inside gate arrays (they were
used on automotive, compact disc drivers, set top boxes and so on) and
when they decide to make LPC2000 played with some bricks taken by their
gate arrays design (from proprietary designs) so the first steps were
fast. When they decide to be more market-ready they had a lot of things
to design and redesign, they start to make more errors (as seen with the
Errata Release, very good and honest piece of papers) and, to sell more
and to have every more happy customers, they hear to them, so you ask
they answer.
[Non-text portions of this message have been removed]



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----- Original Message -----
From: "lpc2100_fan"
To:
Sent: Tuesday, November 13, 2007 8:17 AM
Subject: [lpc2000] Re: PIC32 output speed
> --- In l...@yahoogroups.com, "Leon" wrote:
>>
>> The PIC32 can toggle an output pin at 72 MHz, unlike the LPC2000,
> giving a
>> 36 MHz output.
>>
>> Leon
>>
> Leon,
>
> just for the record, using fast I/O on a LPC23xx/24xx you can toggle
> at 72 MHz (fwiw)

Yes, they have done it properly by connecting them to the ARM local bus.
They should have done that on the LPC2000 chips.

Leon



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----- Original Message -----
From: "mjames_doveridge"
To:
Sent: Monday, November 12, 2007 1:27 PM
Subject: [lpc2000] Re: PIC32 output speed
> --- In l...@yahoogroups.com, "Leon" wrote:
>>
>> The PIC32 can toggle an output pin at 72 MHz, unlike the LPC2000,
> giving a
>> 36 MHz output.
>> ?? So can a 36MHz xtal oscillator. Why would you use a PIC32 to
> generate a fixed-frequency square wave? Would not such a chip be
> better used for, say, controlling a washing-machine or toaster oven?

A software DDS, for instance.

Leon



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Leon ha scritto:
>
> The PIC32 can toggle an output pin at 72 MHz, unlike the LPC2000,
> giving a 36 MHz output.

Is it an useful information? Why? Do you need to toggle an output pin
several times? Is this a mesaure of computing power?
May you explaining why are you writing this sentence?

[Non-text portions of this message have been removed]



(You need to be a member of lpc2000 -- send a blank email to lpc2000-subscribe@yahoogroups.com )

Hi,

> Leon ha scritto:
> >
> > The PIC32 can toggle an output pin at 72 MHz, unlike the LPC2000,
> > giving a 36 MHz output.
>
> Is it an useful information? Why? Do you need to toggle an output pin
> several times? Is this a mesaure of computing power?
> May you explaining why are you writing this sentence?

The point is not that the square wave *needs* to be generated, the point of
the argument is how fast it *can* be generated, i.e. the latency of the core
from the initial write to the port register to the pin being changed.

Programmed I/O usually needs to be fairly fast, why else would Philips add
Fast I/O to the newer LPCs other than by recognizing and responding to
customer demand? Just go back through the archives of this group and look
at the postings that say the older LPCs without fast I/O can't do programmed
I/O faster than a SiLabs 8051. Anybody upgrading from a SiLabs 8-bitter
with fast I/O to an allegedly faster ARM would question why they can't
change output pins quickly.

--
Paul Curtis, Rowley Associates Ltd http://www.rowley.co.uk
CrossWorks for ARM, MSP430, AVR, MAXQ, and now Cortex-M3 processors



(You need to be a member of lpc2000 -- send a blank email to lpc2000-subscribe@yahoogroups.com )

Hi, Stephen

> There are plenty of protocols which need fast bit-banged I/O if
> there isn't a suitable peripheral. A JTAG host is one such. I
> currently have a 24 core 800MHz chip (US$ 10 or so in volume) on
> my desk. This makes bit-banging RF feasible, which in turn
> considerably reduces hardware cost.

Dennis says that chip is "getting there" but isn't quite ready yet. And C
for it would be a bit of a b*stard and wouldn't really gain acceptance. Why
does Chuck like non-standard word sizes so much?

--
Paul Curtis, Rowley Associates Ltd http://www.rowley.co.uk
CrossWorks for ARM, MSP430, AVR, MAXQ, and now Cortex-M3 processors



(You need to be a member of lpc2000 -- send a blank email to lpc2000-subscribe@yahoogroups.com )

----- Original Message -----
From: "Stephen Pelc"
To:
Sent: Tuesday, November 13, 2007 11:23 AM
Subject: [lpc2000] Re: PIC32 output speed
>> Posted by: "stevech11" s...@san.rr.com stevech11
>> Date: Mon Nov 12, 2007 7:48 pm ((PST))
>
>> Many embedded microprocessors can be configured to toggle an I/O pin
>> whenever a timer overflows. Thus, the speed of the CPU is unimportant.
>>
>> I have to say, this discussion about 72MHz I/O bit toggling is silly.
>
> There are plenty of protocols which need fast bit-banged I/O if
> there isn't a suitable peripheral. A JTAG host is one such. I
> currently have a 24 core 800MHz chip (US$ 10 or so in volume) on
> my desk. This makes bit-banging RF feasible, which in turn
> considerably reduces hardware cost.

Steve, what chip is that?

The Parallax Propeller has eight 32-bit cores running at 20 MIPS. It can
generate RF into the VHF region, as well. Someone has developed a Forth for
it.

Leon



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> Many embedded microprocessors can be configured to toggle an I/O pin
> whenever a timer overflows. Thus, the speed of the CPU is unimportant.
>
> I have to say, this discussion about 72MHz I/O bit toggling is silly.
>

Some might say that the OP was t******g, but I couldn't possibly comment.

Rgds,
Martin



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> Posted by: "Paul Curtis" p...@rowley.co.uk paul_l_curtis

> Dennis says that chip is "getting there" but isn't quite
> ready yet.

NDAs apply, but ... a new large batch is currently going onto
evaluation boards. If you want one and can justify it, talk to
me off line.

> And C for it would be a bit of a b*stard and wouldn't
> really gain acceptance.

With the current ROM (not Flash) and RAM split, you've only got
a few hundred instruction slots for application use in each core
and the instruction set is not C-friendly. With this little
code space, you may as well program each core in assembler.

> Why does Chuck like non-standard word sizes so much?

Because
a) It's a single chip CPU with no external bus,
b) 16 bit audio plus a couple of guard bits
c) He's an extreme minimalist.

As an example of where extreme bit-banging performance works is
that on a SEAforth24, the SDRAM interface is run by a couple of
cores bit-banging the pins. Despite this, you can run the SDRAM
at speeds beyond 100MHz.

Leon, as Paul said, the chip details (SEAforth24A) can be found
at:
http://www.intellasys.net
and I'm Stephen not Steve, please.

Stephen
--
Stephen Pelc, s...@mpeforth.com
MicroProcessor Engineering Ltd - More Real, Less Time
133 Hill Lane, Southampton SO15 5AF, England
tel: +44 (0)23 8063 1441, fax: +44 (0)23 8033 9691
web: http://www.mpeforth.com - free VFX Forth downloads



(You need to be a member of lpc2000 -- send a blank email to lpc2000-subscribe@yahoogroups.com )

Stephen,

> > Dennis says that chip is "getting there" but isn't quite
> > ready yet.
>
> NDAs apply, but ... a new large batch is currently going onto
> evaluation boards. If you want one and can justify it, talk to
> me off line.

I'd rather not have another bizarre board. ;-)

This market segment is hotting up, that's undeniable. I didn't think
picoChip would go very far with what they had (hell, what do I know? We even
visited them)--but they focused on a specific market segment and actually
delivered. TILE64 looks interesting, but as always, it's hard to know what
to make of it.

--
Paul Curtis, Rowley Associates Ltd http://www.rowley.co.uk
CrossWorks for ARM, MSP430, AVR, MAXQ, and now Cortex-M3 processors



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--- In l...@yahoogroups.com, Micron Engineering wrote:
>
> Leon ha scritto:
> >
> > The PIC32 can toggle an output pin at 72 MHz, unlike the LPC2000,
> > giving a 36 MHz output.
>
> Is it an useful information?

Subjectively to me - YES, to a local baker probably NOT.

>Why?

It expresses the *rate* of pin state change from one voltage level to
the other under software control.

> Do you need to toggle an output pin several times?

Sometimes.

>Is this a mesaure of computing power?

No, it is a _measure_ (one of many) of a system responsiveness.

> May you explaining why are you writing this sentence?
----^^^^^^ ----------------^^^^^^
Why are you resorting to Ad hominem?

to toggle
intransitive verb : to switch between two options (especially of an
electronic device usually by pressing a single button or a simple key
combination).

w/ best regards
Roger

>
> [Non-text portions of this message have been removed]
>



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--- In l...@yahoogroups.com, "Leon" wrote:
>
> The PIC32 can toggle an output pin at 72 MHz, unlike the LPC2000,
giving a
> 36 MHz output.
>
> Leon
>
Leon,

just for the record, using fast I/O on a LPC23xx/24xx you can toggle
at 72 MHz (fwiw)

Bob



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