Author Topic: iMX RT. New Cortex M7  (Read 18537 times)

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Offline ehughesTopic starter

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iMX RT. New Cortex M7
« on: October 25, 2017, 02:24:42 am »




https://www.nxp.com/products/microcontrollers-and-processors/arm-based-processors-and-mcus/i.mx-applications-processors/i.mx-rt-series:IMX-RT-SERIES

600Mhz Cortex M7 MCU - 40nm tech. 3 bucks in volume.

$80 dev board.   Lots of IO, audio interfaces, etc.     

 

Offline technix

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Re: iMX RT. New Cortex M7
« Reply #1 on: October 25, 2017, 03:51:03 am »
600MHz with DSP extension, seems to be a good Blackfin+ killer. Damn, I spent sp much time on BF706.
Also a potential iMX6ULL killer, which I also unfortunately spent quite some time on.
I don’t see this killing i.MX6ULL. This chip lacked a MMU and thus any support for Linux. Also i.MX6ULL have support for some peripherals.
 

Offline andersm

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Re: iMX RT. New Cortex M7
« Reply #2 on: October 25, 2017, 04:28:12 am »
This chip lacked a MMU and thus any support for Linux.
MMU-less support was merged into the mainline kernel quite some time ago. For example, there's already support for a few ST Cortex-M4 and M7 MCUs.

Offline ataradov

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Re: iMX RT. New Cortex M7
« Reply #3 on: October 25, 2017, 04:29:45 am »
MMU-less support was merged into the mainline kernel quite some time ago.
Too tedious to use and userland sucks.
« Last Edit: October 25, 2017, 05:10:21 am by ataradov »
Alex
 

Offline technix

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Re: iMX RT. New Cortex M7
« Reply #4 on: October 25, 2017, 05:08:28 am »
600MHz with DSP extension, seems to be a good Blackfin+ killer. Damn, I spent sp much time on BF706.
Also a potential iMX6ULL killer, which I also unfortunately spent quite some time on.
I don’t see this killing i.MX6ULL. This chip lacked a MMU and thus any support for Linux. Also i.MX6ULL have support for some peripherals.

I mean DSP usage. A wonderful chip with HS USB, SPDIF receiver, I2S, plenty of CPU power and very low price tag. I'm also looking at STM32H7, though the chip is not yet available. I ordered a board yesterday, and it should arrive in a week.
I would like to see a chip with complete programming framework without Linux and hence the need of external RAM.
I don’t think i.MX6ULL was ever intended to be used for DSP anyway. It is a Linux chip from the get go.
 

Offline technix

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Re: iMX RT. New Cortex M7
« Reply #5 on: October 25, 2017, 05:09:39 am »
This chip lacked a MMU and thus any support for Linux.
MMU-less support was merged into the mainline kernel quite some time ago. For example, there's already support for a few ST Cortex-M4 and M7 MCUs.
That is uClinux. Very few actual userland tool kits support it.
 

Online ali_asadzadeh

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Re: iMX RT. New Cortex M7
« Reply #6 on: October 25, 2017, 06:24:50 am »
Thumbs up, it's been ages that we needed something like this, if I were NXP, I would have added a Radio to the chip too, BLE 5.0 and Wifi :) :) :)
I remember when there was Freesale they had rumours of Kinetis X series that they would make for 4-8MB of flash and 400MHz of speed, so maybe they changed them to i.MX RT
And where did you got the 3$ price tag for the Volume QTY?
« Last Edit: October 25, 2017, 06:30:28 am by ali_asadzadeh »
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Offline tszaboo

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Re: iMX RT. New Cortex M7
« Reply #7 on: October 25, 2017, 09:10:17 am »
Price comes from i.MX RT Series Fact Sheet
It is already listed at Digikay, 5.3 USD @ 240PCS, so far it seems to be the cheapest Cortex M7. Though, you need flash for it, and I am wondering how fast the code runs from external flash.
It is cheaper than NXPs own Cortex M4 offerings, which put them in a strange place. Also, kudos for the LQFP package. Good to see, that companies understand that sometimes we need high speed MCU without designing a 6 layer board.
 

Offline coppice

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Re: iMX RT. New Cortex M7
« Reply #8 on: October 25, 2017, 09:27:00 am »
This chip lacked a MMU and thus any support for Linux.
MMU-less support was merged into the mainline kernel quite some time ago. For example, there's already support for a few ST Cortex-M4 and M7 MCUs.
With the memory constraints of most M4 and M7 chips its more of a stunt to run uCLinux than a practical solution.
 

Online JPortici

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Re: iMX RT. New Cortex M7
« Reply #9 on: October 25, 2017, 09:45:34 am »
Also, kudos for the LQFP package. Good to see, that companies understand that sometimes we need high speed MCU without designing a 6 layer board.

yeah, but without LCD interface and graphics accelerator :-- i think PIC32MZ DA is still attractive for a low cost 2/4 layer solution, even if the chip is ~2.5x more expensive it still come in a 176-TQFP package with both FLASH and DRAM builtin
176 TQFP wouldn't have been much bigger...
 

Offline coppice

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Re: iMX RT. New Cortex M7
« Reply #10 on: October 25, 2017, 09:49:31 am »
It is cheaper than NXPs own Cortex M4 offerings, which put them in a strange place.
That's hard to really tell unless you've tried serious negotiations for high volumes. However, this new part has no flash. That really gets the die cost down.
 

Offline donotdespisethesnake

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Re: iMX RT. New Cortex M7
« Reply #11 on: October 25, 2017, 10:04:22 am »
There certainly is a gap between high end MCUs running an RTOS and low-end MPUs running with Linux. However, iMX RT seems to fall in the gap rather than bridge it. It doesn't really have enough either for practical MCU or Linux usage. Perhaps there are some real-time applications where a souped up MPU can be useful, or a cheap but crippled Linux-style MPU is useful.

Occasionally I have asked sales folk about some of their offerings that don't seem to fit anywhere, and the typical response is along the lines "because we can" or "a big customer wanted it".

I wonder about the external Flash. Parallel flash would eat up a lot of pins, serial flash would suffer problems with latency? Either way, getting deterministic behaviour might require some careful tuning.
Bob
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Offline andersm

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Re: iMX RT. New Cortex M7
« Reply #12 on: October 25, 2017, 10:05:02 am »
MMU-less support was merged into the mainline kernel quite some time ago. For example, there's already support for a few ST Cortex-M4 and M7 MCUs.
That is uClinux. Very few actual userland tool kits support it.
I know. It can still be fine for eg. single-application devices.

With the memory constraints of most M4 and M7 chips its more of a stunt to run uCLinux than a practical solution.
You would obviously need external memory.

Online ali_asadzadeh

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Re: iMX RT. New Cortex M7
« Reply #13 on: October 25, 2017, 10:24:50 am »
External Quad SPI flash is so damn chip, W25Q64FVSSIG is 8MB and it's under 0.5USD, I think we can extract the flash and execute in internal SRAM for best price and performance ;) :)
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Offline coppice

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Re: iMX RT. New Cortex M7
« Reply #14 on: October 25, 2017, 10:31:53 am »
Occasionally I have asked sales folk about some of their offerings that don't seem to fit anywhere, and the typical response is along the lines "because we can" or "a big customer wanted it".
There is almost always a big customer behind the development of silicon.
I wonder about the external Flash. Parallel flash would eat up a lot of pins, serial flash would suffer problems with latency? Either way, getting deterministic behaviour might require some careful tuning.
Deterministic behaviour goes out the window as soon as you have cache. Most M4 and M7 chips have cache, whether they have an external memory interface or not.
 

Offline tszaboo

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Re: iMX RT. New Cortex M7
« Reply #15 on: October 25, 2017, 10:32:12 am »
It is cheaper than NXPs own Cortex M4 offerings, which put them in a strange place.
That's hard to really tell unless you've tried serious negotiations for high volumes. However, this new part has no flash. That really gets the die cost down.
I am aware that volume pricing works differently. But in my experience, Digikey pricing is usually* a good indication for the expected volume pricing. External Flash is cheap, and interfaces, like QSPI doesn't even make the board more difficult.
Quote
Linux
CAn we stop with the Linux talk? It is obviously not for that, hence the no MMU. And because it is an M series chip. You can go and run your bloatware on something else.
 

Offline technix

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Re: iMX RT. New Cortex M7
« Reply #16 on: October 25, 2017, 10:49:21 am »
Also, kudos for the LQFP package. Good to see, that companies understand that sometimes we need high speed MCU without designing a 6 layer board.

yeah, but without LCD interface and graphics accelerator :-- i think PIC32MZ DA is still attractive for a low cost 2/4 layer solution, even if the chip is ~2.5x more expensive it still come in a 176-TQFP package with both FLASH and DRAM builtin
176 TQFP wouldn't have been much bigger...
PIC32MZ DA with eDRAM runs proper, virtual memory Linux too, loading from an external QSPI Flash.
 

Offline technix

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Re: iMX RT. New Cortex M7
« Reply #17 on: October 25, 2017, 10:53:40 am »
Quote
Linux
CAn we stop with the Linux talk? It is obviously not for that, hence the no MMU. And because it is an M series chip. You can go and run your bloatware on something else.
At least in China everything is either bare metal or Android.
 

Offline coppice

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Re: iMX RT. New Cortex M7
« Reply #18 on: October 25, 2017, 10:57:20 am »
I am aware that volume pricing works differently. But in my experience, Digikey pricing is usually* a good indication for the expected volume pricing.
If you work in a big component vendor, and know the bottom line price of parts in high volume, Digikey prices start to look like random numbers.
External Flash is cheap, and interfaces, like QSPI doesn't even make the board more difficult.
Yep, and we can see more and more MCUs going down this route. I think the key question is whether we will continue to see these MCUs sold with pins for an external flash chip, or whether there will be a migration to MCMs.
 

Offline technix

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Re: iMX RT. New Cortex M7
« Reply #19 on: October 25, 2017, 12:26:16 pm »
I am aware that volume pricing works differently. But in my experience, Digikey pricing is usually* a good indication for the expected volume pricing.
If you work in a big component vendor, and know the bottom line price of parts in high volume, Digikey prices start to look like random numbers.
External Flash is cheap, and interfaces, like QSPI doesn't even make the board more difficult.
Yep, and we can see more and more MCUs going down this route. I think the key question is whether we will continue to see these MCUs sold with pins for an external flash chip, or whether there will be a migration to MCMs.
At least one vendor (GigaDevice) is taking the fast lane on MCM approach. They are one of the major second-tier brands in QSPI to begin with, and now their Cortex-M chips are built with a QSPI and a MCU die in MCM setup.
 

Offline Boscoe

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Re: iMX RT. New Cortex M7
« Reply #20 on: October 25, 2017, 03:51:28 pm »
SD3.0 with 200MHz SDR :). Finally an MCU wot ha fast SD card speed!
 

Offline funkathustra

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Re: iMX RT. New Cortex M7
« Reply #21 on: October 25, 2017, 05:37:55 pm »
Definitely adding a dev board to my next order. Thanks for the find!

Is it just me, or does this part seem fairly light on controls-heavy peripherals (timers, ADCs)? I didn't look at how many channels each FlexTimer has on this part (6 is standard, I believe?), but the raw number of independent counters seems pretty low.

I suppose this part is built more for really heavy-duty algorithm work --- audio phased-array / noise-cancelling, image processing --- than straight-up control?

I jump between Kinetis and STM32 parts all the time, and one thing I like about the F4s is all the freakin' timers they have. Working on a 6-axis motor driver board right now, and I can easily route all motor encoders into dedicated timers, along with PWM speed control, with extra channels to spare.

EDIT: the dev kit has, like, 15 GPIO pins on it. Everything else is dedicated to the CSI, LCD, and audio interfaces... suspicions confirmed?
« Last Edit: October 25, 2017, 05:44:16 pm by funkathustra »
 

Offline Sal Ammoniac

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Re: iMX RT. New Cortex M7
« Reply #22 on: October 25, 2017, 06:02:50 pm »
I suppose this part is built more for really heavy-duty algorithm work --- audio phased-array / noise-cancelling, image processing --- than straight-up control?

I jump between Kinetis and STM32 parts all the time, and one thing I like about the F4s is all the freakin' timers they have. Working on a 6-axis motor driver board right now, and I can easily route all motor encoders into dedicated timers, along with PWM speed control, with extra channels to spare.

EDIT: the dev kit has, like, 15 GPIO pins on it. Everything else is dedicated to the CSI, LCD, and audio interfaces... suspicions confirmed?

For heavy-duty control, the best Cortex-M part is probably the Infineon XMC-4000 series. Very sophisticated and flexible timer logic, etc.
Complexity is the number-one enemy of high-quality code.
 

Offline diyaudio

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Re: iMX RT. New Cortex M7
« Reply #23 on: October 27, 2017, 01:21:13 pm »
600MHz with DSP extension, seems to be a good Blackfin+ killer. Damn, I spent sp much time on BF706.
Also a potential iMX6ULL killer, which I also unfortunately spent quite some time on.
AD needs to wake up in this respect, the black series has long ago exceed its place, the whole involvement with Intel was great at the time. SHARC on the other hand still seem to be a die hard processor with excellent dsp performance.

 
 

Offline coppice

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Re: iMX RT. New Cortex M7
« Reply #24 on: October 27, 2017, 03:13:47 pm »
600MHz with DSP extension, seems to be a good Blackfin+ killer. Damn, I spent sp much time on BF706.
Also a potential iMX6ULL killer, which I also unfortunately spent quite some time on.
AD needs to wake up in this respect, the black series has long ago exceed its place, the whole involvement with Intel was great at the time. SHARC on the other hand still seem to be a die hard processor with excellent dsp performance.
Despite the Blackfin being a dead end, they seem to have had a surge of design ins for various market segments in China over the last 3 or 4 years. I guess when you talk seriously to ADI about decent volumes the prices can get attractively low.
 


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