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Discussion Groups | LPC2000 | LPC214x or AT91SAM7Sxx?
Discussion group dedicated to the Philips LPC2000 family of ARM MCUs
LPC214x or AT91SAM7Sxx? - seangra - Sep 14 17:15:00 2005
Ok, I've been mulling over this for weeks now and I can't really
come to a decision as to which chip I want to use. They both seem
like pretty good chips, with some slight benefits and detriments.
I'm looking at making just a small generic basic system with 128x64
LCD, RS232, USB, MMC and possibly MP3 support.
(Please correct me if I cam wrong on any of the following points)
The AT91SAM7S has DMA for all of it's peripherals, which is nice,
but I'm not sure if it's really necessary for me. The LPC2148 has
an 8KB DMA'd buffer for USB, vs 384byte on AT91. The LPC has a DAC,
but it's only 10-bit so that's really not any use for MP3 output (or
is it?). The LPC also has 128-bit memory access, vs 32-bit for SAM,
and I've heard that can be quite a nice little bonus for execution
speed. The LPC can go up to 512KB flash, vs 256KB for the AT91SAM7S
series, but the AT91 goes up to 64KB RAM, vs only 40KB for LPC. The
LPC can run it's com port at almost any baud rate regardless of
source clock, but the AT91 has a pretty good fractional divider
which gives all usual baud rates anyway, and most of the unusual
ones. The AT91 doesn't require an external OSC, but I can't find
out much info on the capabilities of the RTC (does it even have one?)
Or should I be considering a different set of chips altogether? I
like these SOC's because they're simple and low external component
count. I don't need massive code memory, or fast massive RAM memory
(I can always hook up the RAM chips manually on the GPIO lines and
page the data into RAM). The USB is a great plus, so I think that
these are the chips to go with...
As you can see there are a lot of factors. Does anyone have any
information or suggestions that can help me choose between the two?
Thanks a lot!
(You need to be a member of lpc2000 -- send a blank email to lpc2000-subscribe@yahoogroups.com )
come to a decision as to which chip I want to use. They both seem
like pretty good chips, with some slight benefits and detriments.
I'm looking at making just a small generic basic system with 128x64
LCD, RS232, USB, MMC and possibly MP3 support.
(Please correct me if I cam wrong on any of the following points)
The AT91SAM7S has DMA for all of it's peripherals, which is nice,
but I'm not sure if it's really necessary for me. The LPC2148 has
an 8KB DMA'd buffer for USB, vs 384byte on AT91. The LPC has a DAC,
but it's only 10-bit so that's really not any use for MP3 output (or
is it?). The LPC also has 128-bit memory access, vs 32-bit for SAM,
and I've heard that can be quite a nice little bonus for execution
speed. The LPC can go up to 512KB flash, vs 256KB for the AT91SAM7S
series, but the AT91 goes up to 64KB RAM, vs only 40KB for LPC. The
LPC can run it's com port at almost any baud rate regardless of
source clock, but the AT91 has a pretty good fractional divider
which gives all usual baud rates anyway, and most of the unusual
ones. The AT91 doesn't require an external OSC, but I can't find
out much info on the capabilities of the RTC (does it even have one?)
Or should I be considering a different set of chips altogether? I
like these SOC's because they're simple and low external component
count. I don't need massive code memory, or fast massive RAM memory
(I can always hook up the RAM chips manually on the GPIO lines and
page the data into RAM). The USB is a great plus, so I think that
these are the chips to go with...
As you can see there are a lot of factors. Does anyone have any
information or suggestions that can help me choose between the two?
Thanks a lot!
(You need to be a member of lpc2000 -- send a blank email to lpc2000-subscribe@yahoogroups.com )
Re: LPC214x or AT91SAM7Sxx? - Eric Engler - Sep 14 22:51:00 2005
This is the best comparison I've seen of these popular families. I
didn't see you mention Ethernet but maybe that's not a concern for you.
The AT91SAM7X256 should be out by now and that looks great - you might
want to look at it.
One issue that concerns me: there's an open source downloader to
program flash on Philips devices, but nothing like that exists for the
Atmel devices yet. As I understand it (someone correct me if I'm
wrong), there's no linux downloader (of any kind) for SAM-BA, and
there's no commandline downloader for Windows.
Commandline downloaders are convenient to use with various IDEs that
don't have built-in JTAG support. An open source downloader gives us
IDE authors a good example of how to integrate support for it into
IDEs.
I didn't check to see if Atmel fully documented the SAM-BA API, but it
seems like its closed. They also didn't seem to publish the API for
their DLL either. Or maybe this stuff is documented somewhere, or
maybe it will be soon. Atmel seems like a fairly open company so I'm a
little confused about this.
However, it's also fair to point out that Philips does not support
programming flash over USB at all (you could roll your own code, of
course). but Atmel does (if you can make use of their Windows GUI
program).
Eric
(You need to be a member of lpc2000 -- send a blank email to lpc2000-subscribe@yahoogroups.com )
didn't see you mention Ethernet but maybe that's not a concern for you.
The AT91SAM7X256 should be out by now and that looks great - you might
want to look at it.
One issue that concerns me: there's an open source downloader to
program flash on Philips devices, but nothing like that exists for the
Atmel devices yet. As I understand it (someone correct me if I'm
wrong), there's no linux downloader (of any kind) for SAM-BA, and
there's no commandline downloader for Windows.
Commandline downloaders are convenient to use with various IDEs that
don't have built-in JTAG support. An open source downloader gives us
IDE authors a good example of how to integrate support for it into
IDEs.
I didn't check to see if Atmel fully documented the SAM-BA API, but it
seems like its closed. They also didn't seem to publish the API for
their DLL either. Or maybe this stuff is documented somewhere, or
maybe it will be soon. Atmel seems like a fairly open company so I'm a
little confused about this.
However, it's also fair to point out that Philips does not support
programming flash over USB at all (you could roll your own code, of
course). but Atmel does (if you can make use of their Windows GUI
program).
Eric
(You need to be a member of lpc2000 -- send a blank email to lpc2000-subscribe@yahoogroups.com )
Re: LPC214x or AT91SAM7Sxx? - seangra - Sep 15 2:33:00 2005
--- In lpc2000@lpc2..., "Eric Engler" <englere.geo@y...>
wrote:
> I didn't see you mention Ethernet. The AT91SAM7X256 should be out
> by now and that looks great - you might want to look at it.
I mentioned that in my original post. Yes it's 256K/64K, however
it's 2x the cost of the 64K/16K, and about 40% more expensive than
the LPC2148 512K/40K. The LPC2148 is the same price as the
128K/32K, so with that comparison I can get more memory with the
LPC. However I don't know why the LPC doesn't offer 64KB (or 72KB
as their logic goes), as that would be a major plus for them. 40KB
vs 64KB is a larger difference than 128K vs 512K flash, at least in
some circumstances.
Ethernet is really of no use to me in my short-term plans, an it's
fairly easy to add in as an external component later on anyway.
> There's an open source downloader for the Philips devices, but
> nothing like that for Atmel. As I understand it there's no linux
> downloader for SAM-BA, and no Windows command-line downloader.
Good point. Thanks for mentioning that, however I'd imagine (hope!)
that there will be an open source one soon.
> Philips does not support programming flash over USB at all, Atmel
> does (via their Windows GUI program).
I didn't realize this either. How fast does the Philips boot-loader
download at? If 115.2 then it's not that big a deal, as even
downloading 512KB can be done in less than 45 seconds. Usually
you'll have much less code than that anyway. As you mention you can
always create your own bootloader to run over USB. I imagine that
someone will make one and open source it pretty soon anyway.
How useful is the 10-bit DAC? That's too low for MP3 playback,
isn't it?
Right now the only major pluses for Atmel is the ability to have
64KB on-chip RAM, and the fact that all peripherals are DMA'd,
including UART communications. Philips has much more flash, 128-bit
memory access (noticeably faster from what I hear), is cheaper, has
13 more GPIO lines, has a DAC, has 32-bit timers, and is 5MHz faster.
Considering how all of my microcontroller development over the past
2 years has been with a whopping 12KB of ram, I'm sure that 32KB is
enough as long as you are smart with your memory usage. I don't
plan on doing huge RS232 transfers (for which the DMA would be
useful on the SAM7S), especially since there is USB available. Add
in the fact that I can add external "slow-speed" SRAM to either
device, and it looks like the LPC2148 is winning the race.
Although I'd still appreciate any comments that anyone else has to
make.
Thanks!
(You need to be a member of lpc2000 -- send a blank email to lpc2000-subscribe@yahoogroups.com )
wrote:
> I didn't see you mention Ethernet. The AT91SAM7X256 should be out
> by now and that looks great - you might want to look at it.
I mentioned that in my original post. Yes it's 256K/64K, however
it's 2x the cost of the 64K/16K, and about 40% more expensive than
the LPC2148 512K/40K. The LPC2148 is the same price as the
128K/32K, so with that comparison I can get more memory with the
LPC. However I don't know why the LPC doesn't offer 64KB (or 72KB
as their logic goes), as that would be a major plus for them. 40KB
vs 64KB is a larger difference than 128K vs 512K flash, at least in
some circumstances.
Ethernet is really of no use to me in my short-term plans, an it's
fairly easy to add in as an external component later on anyway.
> There's an open source downloader for the Philips devices, but
> nothing like that for Atmel. As I understand it there's no linux
> downloader for SAM-BA, and no Windows command-line downloader.
Good point. Thanks for mentioning that, however I'd imagine (hope!)
that there will be an open source one soon.
> Philips does not support programming flash over USB at all, Atmel
> does (via their Windows GUI program).
I didn't realize this either. How fast does the Philips boot-loader
download at? If 115.2 then it's not that big a deal, as even
downloading 512KB can be done in less than 45 seconds. Usually
you'll have much less code than that anyway. As you mention you can
always create your own bootloader to run over USB. I imagine that
someone will make one and open source it pretty soon anyway.
How useful is the 10-bit DAC? That's too low for MP3 playback,
isn't it?
Right now the only major pluses for Atmel is the ability to have
64KB on-chip RAM, and the fact that all peripherals are DMA'd,
including UART communications. Philips has much more flash, 128-bit
memory access (noticeably faster from what I hear), is cheaper, has
13 more GPIO lines, has a DAC, has 32-bit timers, and is 5MHz faster.
Considering how all of my microcontroller development over the past
2 years has been with a whopping 12KB of ram, I'm sure that 32KB is
enough as long as you are smart with your memory usage. I don't
plan on doing huge RS232 transfers (for which the DMA would be
useful on the SAM7S), especially since there is USB available. Add
in the fact that I can add external "slow-speed" SRAM to either
device, and it looks like the LPC2148 is winning the race.
Although I'd still appreciate any comments that anyone else has to
make.
Thanks!
(You need to be a member of lpc2000 -- send a blank email to lpc2000-subscribe@yahoogroups.com )