Author Topic: Small MCU system-on-module options?  (Read 5858 times)

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Offline jt

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Small MCU system-on-module options?
« on: January 19, 2016, 10:26:14 am »
Does anyone know of a compact system on module for a "medium" performance microcontroller? 

By medium I mean something along the line of an Cortex-M3 or M4 with <400MHz system clock (like a STM32F3/4 or Renesas S7) and external SRAM on the order of 1MB or so.  NAND flash optional, bonus points for on-board Bluetooth LE capability. 

By compact I mean something along the line of <10 cm^2.  Similar to Gumstix modules or the Logic-PD torpedo.  For example, I would consider the following too large: 
http://www.teamfdi.com/product-details/syg-s7g2-som

I see options for higher performance systems (like ~1GHz omap or snapdragon processors with DDR2) but I'm not having much luck finding anything for this niche.

 

Offline donotdespisethesnake

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Re: Small MCU system-on-module options?
« Reply #1 on: January 19, 2016, 07:53:28 pm »
I occasionally look for that type of thing, but I have never seen anything that small, nearest I have seen http://www.emcraft.com/products/224, plus a few similar ones e.g. from Embest.
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Offline miguelvp

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Re: Small MCU system-on-module options?
« Reply #2 on: January 19, 2016, 08:43:21 pm »
Maybe under performers but the PSoC 5LP are pretty good with low power consumption:

My current project:
http://www.eevblog.com/forum/projects/no-bitbanging-necessary-or-how-to-drive-a-vga-monitor-on-a-psoc-5lp-programmabl/

They can only go up to 80MHz with an external XTAL but very configurable.

On top of the datasheet check out the TRM and register TRM:

http://www.cypress.com/documentation/technical-reference-manuals/psoc-5lp-architecture-trm

http://www.cypress.com/documentation/technical-reference-manuals/psoc-5lp-registers-trm-technical-reference-manual

Windows only, but with the register TRM you could do your own app to set them up.

Also on their roadmap I didn't see any Cortex M4 on the PSoC form (they have them without the programable digital and analog stuff on their FM4 family), but it seems they have a Cortex M7 in the works.
http://www.cypress.com/file/151491/download

Depending what you need to do, maybe their PSoC 4 M Series will have something.

My favorite kit from them: CY8CKIT-059
http://www.cypress.com/documentation/development-kitsboards/cy8ckit-059-psoc-5lp-prototyping-kit-onboard-programmer-and

They just introduced a PSoC 4 M kit:
http://www.cypress.com/documentation/development-kitsboards/cy8ckit-043-psoc-4-m-series-prototyping-kit
That takes an optional Bluetooth LE chip:
http://www.cypress.com/products/ez-ble-module-bluetooth-smart

Some more info on this post:
http://www.eevblog.com/forum/microcontrollers/grab-a-psoc-4-m-series-proto-kit-for-$10/msg816218/#msg816218



 

Offline westfw

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Re: Small MCU system-on-module options?
« Reply #3 on: January 19, 2016, 10:34:08 pm »
Quote
external SRAM on the order of 1MB
That seems to be particularly uncommon.  Most chips these days that have an external memory interface seem to implement DDRn as the bus interface, going straight to the 64MB+ domain (running linux!)

Some of the MIPS-core WiFi router modules might meet your requirements.  "Carambola" or "Arduino Yun Mini" perhaps?
 

Offline blueskull

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Re: Small MCU system-on-module options?
« Reply #4 on: January 20, 2016, 11:25:31 am »
Atmel M7 SoC with up to 384K RAM and 300MHz clock.

Or Blackfin+ (70x) with up to 1M L2 SRAM and 64k L1 I-RAM and 64k L1 D-RAM plus 8K L1 scratchpad. Operates at 400MHz with true single cycle 32bit foxed point MAC.

Both available in single chip that requires only power, reset and crystal, all peripherals are integrated.

For connectivity, CC3100 or CC2540 offer WiFi and BLE support at very low cost.

On the other hand, you can wait for ESP32 -- ESP8266's big brother to debut, which offers significantly higher CPU performance and WiFi+BT on chip.

Correction: ESP32 comes without BT, only WiFi. 2*160MHz core (compared to 1*80MHz core overclockable yo 160MHz), and comes with native English documents.
« Last Edit: January 20, 2016, 11:27:58 am by blueskull »
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Offline MT

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Re: Small MCU system-on-module options?
« Reply #5 on: January 20, 2016, 12:00:35 pm »
Speaking of which are there any interface connector standards for small boards like this?
DIP28-64 gumstick/stamp and Aurdino ofcourse but what else?
RPI and others have have IDC connectors but.....   
« Last Edit: January 20, 2016, 12:03:13 pm by MT »
 

Offline blueskull

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Re: Small MCU system-on-module options?
« Reply #6 on: January 20, 2016, 12:04:01 pm »
Speaking of which are there any interface connector standards for small boards like this?
DIP28-64 gumstick/stamp and Aurdino of course but what else?
RPI and others have have IDC connectors but.....

No, AFAIK. Unless your "board" goes very complicated, then you have COM-express or PC104.
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Offline MT

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Re: Small MCU system-on-module options?
« Reply #7 on: January 20, 2016, 12:07:51 pm »
Was not aware of COM express, thanks for info, have to do some read up on it.
 

Offline blueskull

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Re: Small MCU system-on-module options?
« Reply #8 on: January 20, 2016, 12:09:11 pm »
Was not aware of COM express, thanks for info, have to do some read up on it.

Hint: COMe modules are usually very expensive.
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Offline MT

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Re: Small MCU system-on-module options?
« Reply #9 on: January 20, 2016, 12:15:12 pm »
Yes i thought so too! Hmm, see now that COM express is also standard one have to buy! 400usd for card base design...
Ah well, perhaps SODIMM/simple card edge, could be an open standard for very small stamp sized computer modules....

That ESP32 looks interesting...
« Last Edit: January 20, 2016, 12:25:59 pm by MT »
 

Offline blueskull

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Re: Small MCU system-on-module options?
« Reply #10 on: January 20, 2016, 12:23:23 pm »
Yes i thought so too! Hmm, see now that COM express is also standard one have to buy! 400usd for card base design...
Ah well, perhaps SODIMM/simple card edge, could be an open standard for very small stamp sized computer modules....

Well, there are ways to get specs without paying $400. You can try to get a copy of module datasheet from mfg, and they usually have dimensions and signal descriptions.
But since you do not have the full spec, you might end up designing something that works, but not very properly.
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Online Koen

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Re: Small MCU system-on-module options?
« Reply #11 on: January 20, 2016, 12:41:59 pm »
Or Blackfin+ (70x) with up to 1M L2 SRAM and 64k L1 I-RAM and 64k L1 D-RAM plus 8K L1 scratchpad. Operates at 400MHz with true single cycle 32bit foxed point MAC.

Both available in single chip that requires only power, reset and crystal, all peripherals are integrated.
Is there an alternative to the Micriµm FS and USBDevice libraries ? Thank you !
 

Offline blueskull

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Re: Small MCU system-on-module options?
« Reply #12 on: January 20, 2016, 02:52:10 pm »
Or Blackfin+ (70x) with up to 1M L2 SRAM and 64k L1 I-RAM and 64k L1 D-RAM plus 8K L1 scratchpad. Operates at 400MHz with true single cycle 32bit foxed point MAC.

Both available in single chip that requires only power, reset and crystal, all peripherals are integrated.
Is there an alternative to the Micriµm FS and USBDevice libraries ? Thank you !

Yes, you can roll your own USB stack. I'm working on this and got some preliminary results. However, I'm not ready to open source it yet.
It will be made OSS, but only after I have time to really make it work. I'm currently quite busy.
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Offline jt

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Re: Small MCU system-on-module options?
« Reply #13 on: January 20, 2016, 03:06:51 pm »
Thanks everyone!

So it sounds like the options are either a single MCU solution with <1MB internal SRAM, or Linux capable system with >100MB DDR2/3 or so. Interesting there isn't much of a middle ground, but this does seem to follow the trend of product tear downs I've seen.  For example the FitBit and Pebble watch are single MCU solutions (Gecko and STM32F4 respectively) and the Apple, Samsung watches go the high performance ~1GHz, ~512MB RAM route - no middle ground.

Are MCU + external SRAM systems a relic of the past?  I used to work for a company that had implemented this type of embedded system and I was always suspicious the system architect might have been a bit stuck-in-his-ways.  Seems like now I only see the SRAM devices paired with FPGAs. 

Perhaps the blackfins give a middle ground, I hadn't looked at these much before.  Can anyone speak to how good (or bad) the supporting development tools are for these?  Is this product line alive and healthy?  I don't recall seeing many of these used in the past 5 years or so; maybe they are niche to a certain industry? 

I'm starting to come around to the Linux-capable class of device.  The mW sleep modes they offer may still allow my power budget to close.  It would appear my application can tolerate the sleep/wake latency and low duty cycles.   



 

Offline blueskull

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Re: Small MCU system-on-module options?
« Reply #14 on: January 20, 2016, 03:24:27 pm »
BF53x are used MASSIVELY in Chinese (translation: Rigol, Siglent) scopes and IP cameras (being replaced by HiSilicon chipsets now).
BF561 is not seen to be used anywhere in consumer devices.
BF592 is commonly used in low end audio gears (no native 32 bit MAC), uber cheap. $1.99=200MHz, $3.99=400MHz. Poor (68k) L1, no L2.
BF6xx is something I never kept an eye on, so no comments made.
BF70x is the latest one with native 32 bit MAC and 72 bit accumulator as well as a bunch of high perf digital peripherals. Like other BF devices, their on chip analog peripherals suck.

BF53x, 592, 70x operates up to 400MHz (some exceptions). BF600 operates at 600MHz at much higher price. BF561 is dual core.

--------------------

Their product support is kinds okay, but community support sucks. No mature user group, there are only ~4 posts in BF7xx section of their official forum per day.
Among the 4 posts, almost all replies are made by ADI employees -- which means virtually no community help can be found.
They are not budget friendly. So far, the latest 6xx and 7xx processors are not, and probably will not be, supported by GCC, so the only choice is $995 CCES.
That also means no ucLinux, so you have to pay another $8000 on uc-OSiii PER PRODUCT IDEA, unless you want to run on bare metal which I chose to do.
It is a bit disgusting that to promote Micrium middleware, they do not provide some example code, such as USB examples, so they force you to use their middleware.

--------------------

Bottom line: if you have the time and capability to roll everything of your own, then go for it. For the same MIPS, BF+ is really cheap and power efficient compared to its TI rivals.
The support and user base is not nearly on par with what TI offers, so prepare for unforeseen difficulties.
I have experience with 592 and 706. Their perf/buck and perf/watt are fantastic, unfortunately, so do their R&D efforts.
« Last Edit: January 20, 2016, 04:32:00 pm by blueskull »
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Offline miguelvp

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Re: Small MCU system-on-module options?
« Reply #15 on: January 20, 2016, 03:31:42 pm »
Are MCU + external SRAM systems a relic of the past? 

No, for example that PSoC 5LP (Cortex M3) seems to supports 24 bits of address space for external memory that their external memory interface can address.

0x60000000–0x60FFFFFF External Memory Interface

Page 21 of their Datasheet:
http://www.cypress.com/file/45906/download

Page 97 of the Architecture TRM I linked earlier.

Supports 4 types of memory:  synchronous SRAM, asynchronous SRAM, cellular RAM/PSRAM, and NOR flash
and the memory can be 8 or 16 bits wide.

So 16777216 addresses time 2 bytes wide is 32MB.
But on synchronouse SRAM it seems it's only 17 bits address space and 18 bits address space for asynch.

In any event it's posible in this and probably many other MCUs.

 

Offline jt

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Re: Small MCU system-on-module options?
« Reply #16 on: January 20, 2016, 03:38:10 pm »
Quote
No, for example that PSoC 5LP (Cortex M3) seems to supports 24 bits of address space for external memory that their external memory interface can address.

Yeah, I know the STM32F(1-4) devices also support SRAM with their external memory bus.  I just haven't seen this implemented in many products;  perhaps I'm not looking in the right places.
 

Offline jt

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Re: Small MCU system-on-module options?
« Reply #17 on: January 20, 2016, 03:48:48 pm »
Thanks  blueskull for your feedback on the blackfin support.  I think you've confirmed my suspicion that there isn't much of a community and I haven't heard good things about Analog Dev. support in general. 

This is a side project with some buddies, so we are definitely looking to leverage as much community work as possible.  Sounds like that rules these out. 

 

Offline donotdespisethesnake

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Re: Small MCU system-on-module options?
« Reply #18 on: January 20, 2016, 09:39:51 pm »
So it sounds like the options are either a single MCU solution with <1MB internal SRAM, or Linux capable system with >100MB DDR2/3 or so. Interesting there isn't much of a middle ground, but this does seem to follow the trend of product tear downs I've seen.

Yes, I've noted the lack of a middle ground before. The biggest MCU's usually have much less than 1MB on board, with a few exceptions.

If you move up to Linux class then you are spoiled for choice again. Some of the modules can be programmed bare metal, or with RTOS like FreeRTOS, but you have to do all the stuff like USB host, networking, device drivers for wireless. Linux provides all that and more out of the box, so if you need simple external IO with a rich, connected app then it's a quick win. With a bit of creativity you can do some advanced low level things as well, or interface to an external MCU.

I would take a close look at what you can do with the Raspberry Pi Compute module.
Bob
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Offline ale500

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Re: Small MCU system-on-module options?
« Reply #19 on: January 20, 2016, 10:04:50 pm »
You can try some MPC57xx from freescale, some have like 1,5 MB built-in RAM. But I'd go for a ST32F4xx with external ram, much cheaper. Some of them support QSPI, so if your RAM doesn't have to be super fast it may be an option, if not you can go for 4x512kx8 or 2x256kx16 as external RAM, don't forget that those SRAM are 10 ns or more...

A ST32F439 Discovery board has 8MB SDRAM on board, you may want to have a look at it as a starting platform, it is quite cheap at ~ 20 €,. Schematics are also available.
I'd also love something like that, a small board with CPU+SRAM (I have a ST32F439 Disco and works quite well!) but I don't want a TQFP176 or so and thus I'd go with a PIC32MZ, they have 512k SRAM built-in and QSPI, all in TQFP-64... not bad !. They go for like 10 € each.
« Last Edit: January 20, 2016, 10:06:29 pm by ale500 »
 

Online nctnico

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Re: Small MCU system-on-module options?
« Reply #20 on: January 20, 2016, 10:27:33 pm »
Or Blackfin+ (70x) with up to 1M L2 SRAM and 64k L1 I-RAM and 64k L1 D-RAM plus 8K L1 scratchpad. Operates at 400MHz with true single cycle 32bit foxed point MAC.

Both available in single chip that requires only power, reset and crystal, all peripherals are integrated.
Is there an alternative to the Micriµm FS and USBDevice libraries ? Thank you !
LUFA which is also ported by NXP for their own devices. Speaking of NXP: AFAIK they have several ARM devices which support external memory which would fit the OP's requirements.
« Last Edit: January 20, 2016, 10:30:13 pm by nctnico »
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Offline jt

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Re: Small MCU system-on-module options?
« Reply #21 on: January 21, 2016, 03:52:38 am »
Quote
Some of them support QSPI, so if your RAM doesn't have to be super fast it may be an option

Thanks, I wasn't aware that QSPI RAM existed, so it isn't an option I have traded.  My hope was to find a system on module that would offload the high density PCB technology from my board, but maybe with QSPI I can still keep things reasonably small, but still easy to hand load.  At first blush, I don't think I need the RAM to be very fast. 
 

Offline ale500

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Re: Small MCU system-on-module options?
« Reply #22 on: January 23, 2016, 03:16:22 am »
These QSPI RAMs can be accessed in "memory mapped mode" meaning, you don't care about the SPI protocol at all, it is all transparent. You can get a nucleo or discovery board with a compatible CPU:

http://www.st.com/web/en/catalog/mmc/SC1169/SS1577

The PIC32MZ could also be a candidate, it has more inernal RAM and QSPI.

QSPI SRAM top at 128kx8 like: http://www.farnell.com/datasheets/1647941.pdf
 

Offline jt

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Re: Small MCU system-on-module options?
« Reply #23 on: January 23, 2016, 05:23:11 pm »
Thanks for the info!  I'm always excited to learn of new circuit building blocks
 

Offline Kilrah

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Re: Small MCU system-on-module options?
« Reply #24 on: January 24, 2016, 09:32:35 am »

Yeah, I know the STM32F(1-4) devices also support SRAM with their external memory bus.  I just haven't seen this implemented in many products;  perhaps I'm not looking in the right places.

There's a product on which I'm currently collaborating that does this, an STM32F4 and 8MB external RAM. Pretty similar to the F439 discovery board, the RAM is needed for the framebuffer for the relatively high resolution LCD, and will also be useful for other purposes now it's there...

But it's a pretty specific application where a microcontroller is really appropriate for the purpose (real-time operation required, several timers with the common hardware capture/compare functionality needed, need ADCs and DACs for which integrated peripherals are good enough and external parts wouldn't be worth the cost and effort)... but nowadays the vast majority of consumer products have more use for the high computing performance, non real time platforms.
 


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