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Imperf3kt
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What exactly is the CM3L, and is it suitable for my project?

Tue Nov 14, 2017 4:56 am

I've looked at the product pages for the compute module 3 and 3 lite but find them almost useless for an informed purchase.

From the tiny amount of information (mainly images) available on the page, a CM3L is a Raspberry Pi3 in the shape of an SO-DIMM chip and lacking any peripheral connections altogether, instead opting to have every connection on the bottom (?) of the board as pads I can solder to or slot into a SO-DIMM connector.

So in order to use this module I would need to install anything I intended to use, including the SD Card holder and HDMI out etc? Or I could purchase the I/O board to make life easier? (Not an option for me due to the size)

I am interested in this revision of Pi for the basis of a handheld gaming console which can also be used to program your own games.
The Pi3b is almost perfect for this except for a few minor limitations (Limited RAM, some issues with OpenGL, faulty audio over bluetooth, USB ports in an inconvenient position, etc)

I have a working prototype which I am currently ironing the kinks out of, but it suffers from being too thick (and way too hot. At an ambient temperature of 21℃ and not enclosed in a case, I was seeing the SoC throttling merely playing SD video on Youtube over Epiphany)

I imagine the CM3Lto be just what I need, provided it is what I think it is.

Can anybody offer theur opinion please? Is the CM3L suitable for this?

I won't be making this thing commercial, however I will be providing a full guide on producing your own once I have finished.
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aBUGSworstnightmare
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Re: What exactly is the CM3L, and is it suitable for my project?

Tue Nov 14, 2017 6:03 am

If the RPi 3b has limited RAM you will face the same problem with the compute module 3 as both have 1GB RAM 'only'.

Compute Module needs a base board. The official foundation board is just an example of such a board and can be used when developing your own. CM1/3 can be used in industrial applications due to its longevity .

Here are a few commercial examples base boards for CM1/3:
https://www.wdc.com/de-de/products/wdla ... WDLB005RNN
https://www.wdc.com/de-de/products/wdla ... WDLB031RNN
https://www.wdc.com/de-de/products/wdla ... WDLB004RNN

Use google and you will find a lot more.

Conclusion: You will have to develop your own baseboard with the peripherals you need.

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Imperf3kt
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Re: What exactly is the CM3L, and is it suitable for my project?

Tue Nov 14, 2017 6:10 am

I can work around the RAM limitation and am researching a few options now.

My main concern was what I needed to turn a compute module inti what I currently have.

I'll Google around a bit, but it seems somewhat silly to have to google what a product has because the official site lacks such info.
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fruitoftheloom
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Re: What exactly is the CM3L, and is it suitable for my project?

Tue Nov 14, 2017 7:28 am

Imperf3kt wrote:
Tue Nov 14, 2017 6:10 am
I can work around the RAM limitation and am researching a few options now.

My main concern was what I needed to turn a compute module inti what I currently have.

I'll Google around a bit, but it seems somewhat silly to have to google what a product has because the official site lacks such info.


On the Official Web Site it states Industrial Compute Module, therefore your nitpicking is without merit:

https://www.raspberrypi.org/products/

Element14 has more detaild:

https://www.element14.com/community/doc ... e-module-3
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aBUGSworstnightmare
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Re: What exactly is the CM3L, and is it suitable for my project?

Tue Nov 14, 2017 8:43 am

Let me add to this https://www.raspberrypi.org/documentati ... /README.md

Gives you all the Details you Need to know in order to start working with a compute module.
The Compute Modules give users full flexibility; that's why it was developed.

I.e. I'm working on a base board which gives me dual channel LVDS Output, allowing me to connect TFT modules of nearly every size. My board will neither have USB, but provisions for connecting a USB hub. As I want to have good Audio Quality my baseboard will have a Stereo DAC.

Sure, doing such a development requires time, Know-how and money. But it will give me exactly what I Need once completed.

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Imperf3kt
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Re: What exactly is the CM3L, and is it suitable for my project?

Tue Nov 14, 2017 9:22 am

fruitoftheloom wrote:
Tue Nov 14, 2017 7:28 am
Imperf3kt wrote:
Tue Nov 14, 2017 6:10 am
I can work around the RAM limitation and am researching a few options now.

My main concern was what I needed to turn a compute module inti what I currently have.

I'll Google around a bit, but it seems somewhat silly to have to google what a product has because the official site lacks such info.
On the Official Web Site it states Industrial Compute Module, therefore your nitpicking is without merit:

https://www.raspberrypi.org/products/

Element14 has more detaild:

https://www.element14.com/community/doc ... e-module-3
I'm not blind, I can read.
Here's what the Raspberry Pi products page says the compute module is.
The Compute Module 3 is a Raspberry Pi 3 in a more flexible form factor, intended for industrial application
Yeah... I kinda already knew that much, its why I'm considering buying one.

Let's scroll down to "specifications"
The Compute Module 3 contains the guts of a Raspberry Pi 3 (the BCM2837 processor and 1GB RAM) as well as a 4GB eMMC Flash device (which is the equivalent of the SD card in the Pi). The Pi 3 has a processor speed of 1.2GHz and runs at roughly 10 times the speed of the Pi 1 due to its quad-core CPU. This is all integrated on to a small 67.6mm x 31mm board which fits into a standard DDR2 SODIMM connector (the same type of connector as used for laptop memory). The Flash memory is connected directly to the processor on the board, but the remaining processor interfaces are available to the user via the connector pins. You get the full flexibility of the BCM2837 SoC (which means that many more GPIOs and interfaces are available as compared to the Raspberry Pi), and designing the Module into a custom system should be relatively straightforward as we’ve put all the tricky bits onto the Module itself.

The Compute Module is available for purchase in single units, or in batches of hundreds or thousands. To get started designing a PCB to use the Module, we provide an open-source breakout board with a single Module in an affordable development kit.

A lite version of the Compute Module 3 is also available. The CM3L brings the SD card interface to the Module pins so a user can wire this up to an eMMC or SD card of their choice.
This doesn't tell me much more than the last paragraph did.
This part in particular is actually confusing.
we’ve put all the tricky bits onto the Module itself.
I'd consider the HDMI port to be one of those "tricky parts", but I can't see one in the images, hence my confusion as to whether it has any ports or not.

It doesn't help that I was viewing the page via a smartphone.
aBUGSworstnightmare wrote: Let me add to this https://www.raspberrypi.org/documentati ... /README.md

Gives you all the Details you Need to know in order to start working with a compute module.
The Compute Modules give users full flexibility; that's why it was developed.

I.e. I'm working on a base board which gives me dual channel LVDS Output, allowing me to connect TFT modules of nearly every size. My board will neither have USB, but provisions for connecting a USB hub. As I want to have good Audio Quality my baseboard will have a Stereo DAC.

Sure, doing such a development requires time, Know-how and money. But it will give me exactly what I Need once completed.
Thank you, that looks like what I require.
I wonder why there is no link within the product page. How did you get that document?
Pi3b - 'normal use' temperature (25% CPU load) 76℃, ambient 21℃

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fruitoftheloom
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Re: What exactly is the CM3L, and is it suitable for my project?

Tue Nov 14, 2017 9:54 am

Imperf3kt wrote:
Tue Nov 14, 2017 9:22 am
I wonder why there is no link within the product page. How did you get that document?

Linked on the HELP page under Documentation:

https://www.raspberrypi.org/help/
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RaTTuS
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Re: What exactly is the CM3L, and is it suitable for my project?

Tue Nov 14, 2017 10:03 am

documentation/hardware/computemodule ...is where it comes from,
there are no ports on the CM, you make them on your carrier board, you have access to more GPIO than the PI3
if your existing board is too think / hot then make the case become the heatsink,
you may have more truck with the customisation service https://www.element14.com/community/doc ... on-service though the price will be more than a Pi3
and you have a minimum number you need to buy
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Imperf3kt
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Re: What exactly is the CM3L, and is it suitable for my project?

Thu Nov 16, 2017 3:56 am

I appreciate the help so far, but it seems my google-fu is lacking.

Assuming I buy a compute module, what precisely (apart from a 'carrier board') do I need so I can use it like a regular Pi3b? Do I need something to flash the emmc with? What about installing emmc (4Gb is not enough), can I hand solder it or must I have it done by a company?

Are there any recommended guides for making your own carrier board?

My searches are turning up nothing useful.
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aBUGSworstnightmare
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Re: What exactly is the CM3L, and is it suitable for my project?

Thu Nov 16, 2017 5:37 am

All you need to know for making your own carrier board is available from the Compute Module Data Sheet and the CMIO board schematics (which you can use as a template).

There is no 'my own carrier board how-to' as everybody as different needs in regards of connectivity/size etc.

Unless you have proper equipment and know-how you should not think about replacing the eMMC. Better to opt for CM3L or the 16GB CM3 from NEC (don't know where/if it's available without one of their monitors).

General question: Do you have experience in electronically engineering at all? Might be a challenge if not!

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Re: What exactly is the CM3L, and is it suitable for my project?

Thu Nov 16, 2017 1:12 pm

Eventually there will be, I hope, some reference designs for carrier boards. However, we have not had a chance to make/document anything yet, so right now, the schematic of the current carrier board is the starting point.

If you don't have any knowledge of PCB design/electronics, you might find this a tad difficult.

Upgrading the eMMC flash yourself might actually be impossible. Best to buy the NEC board if you need more.
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Imperf3kt
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Re: What exactly is the CM3L, and is it suitable for my project?

Thu Nov 16, 2017 8:58 pm

aBUGSworstnightmare wrote:
Thu Nov 16, 2017 5:37 am
All you need to know for making your own carrier board is available from the Compute Module Data Sheet and the CMIO board schematics (which you can use as a template).

There is no 'my own carrier board how-to' as everybody as different needs in regards of connectivity/size etc.

Unless you have proper equipment and know-how you should not think about replacing the eMMC. Better to opt for CM3L or the 16GB CM3 from NEC (don't know where/if it's available without one of their monitors).

General question: Do you have experience in electronically engineering at all? Might be a challenge if not!
I have some experience, but it is minimal. If I recall, the only actual PCB I've created was a circuit to turn an LED off by blowing on a piezo transducer. Acid was used to prepare the traces.
Unless you also consider graphene traces drawn on paper with a pencil.

I understand this will be difficult and my knowledge is limited, but after hitting my head against a wall for months using the Pi3B, I have no other option. I did try a different SBC, but that was not as fruitious as I had hoped.

The requirement for more than 4GB was because I need to install Raspbian Stretch full, which does not fit on anything smaller, even after uninstalling a lot of unwanted packages.


I'll try to go through the schematics more thoroughly soon. Time is difficult to find lately. Need to remember to invent that Raspberry Pi based time machine.
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Re: What exactly is the CM3L, and is it suitable for my project?

Thu Nov 16, 2017 9:07 pm

jamesh wrote:
Thu Nov 16, 2017 1:12 pm
Upgrading the eMMC flash yourself might actually be impossible. Best to buy the NEC board if you need more.
It's been done, but very, very few of us have the equipment and skills to do it. I certainly don't. There as a thread right after the CM3 came out about someone doing so... Here is the start of someone doing it: viewtopic.php?f=98&t=172235

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fruitoftheloom
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Re: What exactly is the CM3L, and is it suitable for my project?

Thu Nov 16, 2017 9:23 pm

Imperf3kt wrote:
Thu Nov 16, 2017 8:58 pm
aBUGSworstnightmare wrote:
Thu Nov 16, 2017 5:37 am
All you need to know for making your own carrier board is available from the Compute Module Data Sheet and the CMIO board schematics (which you can use as a template).

There is no 'my own carrier board how-to' as everybody as different needs in regards of connectivity/size etc.

Unless you have proper equipment and know-how you should not think about replacing the eMMC. Better to opt for CM3L or the 16GB CM3 from NEC (don't know where/if it's available without one of their monitors).

General question: Do you have experience in electronically engineering at all? Might be a challenge if not!
I have some experience, but it is minimal. If I recall, the only actual PCB I've created was a circuit to turn an LED off by blowing on a piezo transducer. Acid was used to prepare the traces.
Unless you also consider graphene traces drawn on paper with a pencil.

I understand this will be difficult and my knowledge is limited, but after hitting my head against a wall for months using the Pi3B, I have no other option. I did try a different SBC, but that was not as fruitious as I had hoped.

The requirement for more than 4GB was because I need to install Raspbian Stretch full, which does not fit on anything smaller, even after uninstalling a lot of unwanted packages.


I'll try to go through the schematics more thoroughly soon. Time is difficult to find lately. Need to remember to invent that Raspberry Pi based time machine.

https://store.gumstix.com/gumstix-pi-co ... board.html
My only "PC" is an Asus ChromeBit running ChromeOS, cloudcentric at its best !
Rockchip Quad-Core RK3288C ARM32 SoC as used in ASUS Chromebook C201 & Chromebook Flip C100PA as well as the Tinker SBC.
3 Mobile Huawei E5330 Mobile Mi-Fi

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