LPC or SAM7?

Does it even matter? I've been doing the smaller micros (PIC, 8052, etc) in assembler for quite a while now, and I'd like to tinker with some ARM type stuff using C (gcc will be fine). I want to be able to use TCP/IP on the board. Looks like Olimex makes some pretty decent looking dev boards for cheap, but I don't know if I should lean towards the LPC line or the SAM7. What say ye?

thanks for reading

Reply to
Anthony Fremont
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It only matters if LPC or SAM7 have the right combination of peripherals that you will think you will need. I personally use analog devices and st micro ARM's.

Reply to
steve

I've used both and now prefer Atmel. I found the interface to internal flash on the LPC's to be a bit quirky, and the SAM7's UART has more features. It's really splitting hairs. If you find a chip with the right set of peripherals, then use it. Most of my code can be ported between SAM7/LPC with minimal effort. It's nice to have a second source ;)

Reply to
Anders

There is a comparison of many ARM7 devices at

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Go to the Resources page and click on the Device Comparison link. You will find a table with many devices although the table is not up to date and there are several new devices that are not included.

I agree with the others that the differences are small compared to the similarities. Both Atmel and Philips have a wide range of peripherals available in many flavors of their devices.

Other than the details of the peripherals, the main difference between the SAM7 and the LPC2 lines are the speed of the CPU and the DMA. The LPC parts run a bit faster with the SAM7 requiring a wait state at speeds above 30 MHz, IIRC and top out at 55 MHz. Some LPC devices rurn at up to 70 MHz for inline code with no wait states, although branches require a flush of the memory buffer. The SAM7 parts can use DMA for peripheral access while the LPC must use program controlled I/ O.

Both families are very low power and all of the others are around double these power levels at full speed. In fact, these 32 bit devices are thriftier than many 8 bit devices when normalized for speed! At very low speeds the other devices use *much* more power than either of these two. Someone has said that they found the SAM7 parts to run at lower power than the LPC, but I don't see that reflected in the data sheets. I have not worked with the LPC parts myself so I can't say.

On the other hand, I don't think any of the ARM families will operate at less than 3.3 volts for I/O, although the cores can run directly from a lower supply saving even more power.

So to say which ARM family is better, you need to define your requirements and see which has strengths that match your requirements.

Reply to
rickman

Really? Don't SAM7's and LPC's peripherals have different software interfaces? DMA is a big one.

Reply to
steve

Just to add to that, I think also the SAM7 parts have a memory interfaced designed predominently for efficient THUMB mode code. They will be slower in ARM mode. Someone correct me if this is wrong.

I particularly like the DMA interface on the SAM7 peripherals. It frees up a lot of CPU cycles for you.

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Richard.
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Reply to
FreeRTOS.org

Sure - the BSP/HW abstraction module takes care of that, and relative to the rest of the code that's a tiny piece and actually pretty simple to rewrite. But you're right, the details of direct hardware access is obviously different, although the concepts are very similar and if you've done it once, porting the BSP is not that difficult.

Granted there may be situations where you have extreme requirements on timing, and need to play around with single instructions to make things work, but I have never had such requirements. That little ARM7 at 47MHz is plenty fast for my apps :)

Reply to
Anders

I guess this makes sense, since critical ARM mode code can always go in RAM, and is likely a small part of the program.

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John Devereux
Reply to
John Devereux

The SAM7A3 is 60 MHz.

It generally does not require a waitstate if you run in Thumb mode, and if you need a few routines running at high speed, then you can copy it to the SRAM, which has slightly higher bandwidth than the LPC flash and is more predictable.

If you start to do heavy communications, then the DMA is your friend. An ARM without DMA on the SPI cannot do too many Mbits before the CPU is using all its MHz on SPI interrupt routines so even if the LPC is running at higher MHz, the SAM7 will maintain its performance even with heavy communication activity.

SAM7L is soon here and will support low voltage I/O.

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Ulf Samuelsson
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Reply to
Ulf Samuelsson

In article , Anthony Fremont writes

LPC see

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A book on the tcp/ip (with source code) based on an IAR/Olimex kit using LPC parts.

Caveat

1 I sell IAR kits (and Olimex and many others but only inthe UK) 2 I know the author of the book
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\/\/\/\/\ Chris Hills  Staffs  England     /\/\/\/\/
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Reply to
Chris Hills

Does this cover the newer LPC parts that have on-chip Ethernet? The website didn't make that clear.

Eric

Reply to
Eric

BookContents.aspx) it seems that it uses the CS8900A and LPC212x, so no on-chip ethernet.

Best regards Pietro

Reply to
nibble

Not the one with on chip but... I think you could modify the source to work with the on chip version. BTW this is a learning/ teaching aid so I don't know how good the stack will be for commercial use or the license it has but as a proof of concept, for learning TCP/IP or for hobby use it should be ideal

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\/\/\/\/\ Chris Hills  Staffs  England     /\/\/\/\/
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Reply to
Chris Hills

You should look at the STR9 ARM Controllers from ST Microelectronics as well. They provide quite a lot of software suitable for arm-gcc. Look at the STR9-comStick which comes with open source TCP/IP code.

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Hitex also has a very nice book "STR9 Insider's Guide." which one can download for free. The STR9-comStick sells for 39 EUR.

Regards Anton Erasmus

Reply to
Anton Erasmus

In article , Anton Erasmus writes

Almost looks like advertising.... you don't have any connection with them do you?

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\/\/\/\/\ Chris Hills  Staffs  England     /\/\/\/\/
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Reply to
Chris Hills

Other than having used LPC and SAM7s as well as ST ARM, and having found the support documentation etc. from ST very much superior to the others .... Then NO, No connection with ST or Hitex.

Regards Anton Erasmus

Reply to
Anton Erasmus

I haven't been ignoring you all, I've just been busy reading up a ton of ARM material between bouts of "ordinary" work. Thanks for all the input, sounds like the key factor for me in choosing a platform is what peripherals are present.

Now Olimex has gone on a month long vacation and sparkfun doesn't have the board I'd like in stock. :-( I'll probably go ahead and get something with network and a hitachi type LCD. The SAM7 thing that I liked had a Nokia color LCD. I'm thinking that would be fun to tinker with, but a free available TCP/IP stack and network jack are the key things I want to mess with right now.

Thanks again. :-)

Reply to
Anthony Fremont

Sparkfun aren't the only ones who sell olimex dev boards. Some may have the board you want in stock

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olimex have very similar boards for

sam7

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lpc2378
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st9
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Dontronics seems to show they have some of the dev boards (olimex) in stock note shipping from Australia to US is cheap unlike US to Australia(triple the cost)

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lpc2378
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Olimex-SAM7-EX-256
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Olimex-STR-E912

The other boards that are really nice and are from luminarymicro.com

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Have a look for the Jim Lynch tutorials

He just has a new one out for the nokia lcd module on the olimex sam7 board

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Atmel version of his tutorial

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Mirror of some of his tutorials (on my site)

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Alex

Reply to
Alex Gibson

I wouldn't mind giving one of the str9-comsticks a go if they didn't try and charge me double the price for shipping. Local disti charges even more as they supposedly pay the inflated shipping cost + customs + markup (cheapest shipping to Australia is 79 Euros from Hitex)

Pity they don't sell them through digikey (like keil does) who would only charge me US$30 for shipping.

Alex

Reply to
Alex Gibson

Luminary has a cheap Ethernet device with an open source stack:

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They're a smaller company and I've had good experiences with their tech support.

Eric

Reply to
Eric

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