jrychter
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CM3 specs

Sun Aug 28, 2016 8:40 am

Hi,

We are building a product based on the Compute Module (and two RPI v2.1 cameras). Production is about to start, and we're about to start working on the next hardware version. However, I am completely in the dark regarding the rumored CM3. I don't actually need an exact shipping date (e.g. "later this year" is fine), but some kind of clarification on the following would help tremendously:

* Will there be on-board WiFi+Bluetooth?
* Do we still get two synchronized CSI cameras with good software support, like on the CM1?
* Will there be a better solution for factory programming than a USB MUX and an USB port just for this purpose?
* Are power requirements similar?
* Should we expect having to redesign our boards when switching from CM1 to CM3?

Also, on a related note, there is some uncertainty regarding V2.1 cameras. I've heard rumors of switching from a 1mm pitch to 0.5mm pitch FFC, which would be catastrophic for people who have things in production.

So, please — some clarification would help a lot for anyone who is building devices that include the CM and RPi cameras.
--J.
Founder at PartsBox: https://partsbox.io/ (keep track of your electronic components)

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rpdom
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Re: CM3 specs

Sun Aug 28, 2016 8:56 am

I'm afraid you will have to wait until the CM3 is released. The RPF/RPT don't release details of their new products until they are ready, partly in case any of the specs need to be changed at any point.

As for the cameras, are you thinking about the small format connector on the Pi Zero? That is the same as the ones on the CM I/O board and also requires an adaptor to connect to the camera.

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Re: CM3 specs

Sun Aug 28, 2016 3:12 pm

One person who has posted on this Forum was doing tests with cameras some time ago with a CM3. Obviously any real information was under NDA, but it was mentioned that he was testing the CM3 using an existing CM1 dev carrier board. So the connector has stayed compatible. The one thing I would expect would be that the CM3 would require more power (going from a 2835 to 2837 SoC). I have a vague memory that someone said that the CM3 board does not have WiFi built on to it.

You might consider trying to contact the RPF directly (these Forums are really Pi users, not a generally official channel). Since you're doing this as part of a company, you are undoubtedly familiar with and routinely deal with NDAs.

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Re: CM3 specs

Sun Aug 28, 2016 3:18 pm

Raspberry Pi Trading are responsible for Hardware ;)
Retired disgracefully.....

6by9
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Re: CM3 specs

Sun Aug 28, 2016 7:46 pm

I guess that reference to a prototype CM3 was for me, as I said here. Please note that I have run a CM1 in a CMIO3, but not the other way around.
plugwash has mentioned uprating the VBAT line. I thought gsh (Pi Towers Director of Software and one of the people behind the Slice media player using CM1, upgradable to CM3 when available) or James Adams (Pi Towers Director of Hardware, and also behind Slice) had made comment, but I can't find it at the moment.
The Slice power setup is going to differ slightly from the CMIO as it also has to power the HDD, but I wouldn't expect much else.
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Re: CM3 specs

Sun Aug 28, 2016 9:23 pm

6by9 wrote:I guess that reference to a prototype CM3 was for me, as I said here. Please note that I have run a CM1 in a CMIO3, but not the other way around.
plugwash has mentioned uprating the VBAT line. I thought gsh (Pi Towers Director of Software and one of the people behind the Slice media player using CM1, upgradable to CM3 when available) or James Adams (Pi Towers Director of Hardware, and also behind Slice) had made comment, but I can't find it at the moment.
The Slice power setup is going to differ slightly from the CMIO as it also has to power the HDD, but I wouldn't expect much else.
That's for that clarification. I must have missed that it was a CM1 in a CM3 dev carrier, rather than the other way around. I'm not surprised that a CM1 would work in a CM3 carrier. (I live is some modest fear of what I'm going to have to pay for a new carrier board....and I hope that WD does an updated SATA adapter to handle the requirements of the CM3)

jrychter
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Re: CM3 specs

Tue Aug 30, 2016 8:53 am

rpdom wrote:I'm afraid you will have to wait until the CM3 is released. The RPF/RPT don't release details of their new products until they are ready, partly in case any of the specs need to be changed at any point.
Sigh. Well, this is a bit of a problem — I mean, in the hobby world, this is perfectly fine, but from what I understand the CM and the V2 cameras are supposed to be money-makers for the RPF, designed for the industrial world. Well the industrial world needs to plan ahead :-)
rpdom wrote:As for the cameras, are you thinking about the small format connector on the Pi Zero? That is the same as the ones on the CM I/O board and also requires an adaptor to connect to the camera.
I don't understand the whole business with adapters on the CM I/O developer board. Cameras have a 15-pin 1mm pitch FFC connector, so why not just stick to that? It's not like the I/O dev board doesn't have enough space.

In any case, I was expressing hope that the cameras that we'll be buying in quantity won't suddenly be phased out for ones with a 0.5mm FFC connector, which would mean halting production, redesigning the main board, prototyping and starting production again.
--J.
Founder at PartsBox: https://partsbox.io/ (keep track of your electronic components)

6by9
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Re: CM3 specs

Tue Aug 30, 2016 10:34 am

jrychter wrote:
rpdom wrote: I'm afraid you will have to wait until the CM3 is released. The RPF/RPT don't release details of their new products until they are ready, partly in case any of the specs need to be changed at any point.
Sigh. Well, this is a bit of a problem — I mean, in the hobby world, this is perfectly fine, but from what I understand the CM and the V2 cameras are supposed to be money-makers for the RPF, designed for the industrial world. Well the industrial world needs to plan ahead :-)
I wouldn't normally suggest hassling those at Pi Towers directly, but a quick PM to gsh (Gordon Hollingworth) may get some answers, and possibly an official response here. They typically don't follow the forums too closely (it'd be a full time job).
jrychter wrote:
rpdom wrote:As for the cameras, are you thinking about the small format connector on the Pi Zero? That is the same as the ones on the CM I/O board and also requires an adaptor to connect to the camera.
I don't understand the whole business with adapters on the CM I/O developer board. Cameras have a 15-pin 1mm pitch FFC connector, so why not just stick to that? It's not like the I/O dev board doesn't have enough space.

In any case, I was expressing hope that the cameras that we'll be buying in quantity won't suddenly be phased out for ones with a 0.5mm FFC connector, which would mean halting production, redesigning the main board, prototyping and starting production again.
The point of the CM is to expose as much functionality as possible. The SoC is capable of 4 lanes CSI2 on the CAM1 interface. The standard Pi connector doesn't have enough pins for that, so they used a different connector that does have enough pins.
There is an ongoing effort to get the CSI2 receiver peripheral working directly via V4L2, at which point having 4 lanes available on a custom CM based board has practical uses. As the standard Pi's (except the Zero) only have a connector that can carry 2 lanes, I'd be very surprised if the Pi Towers supported cameras ever deviated from the 15pin connector and 2 lanes. I'm not sure where you've heard the rumour from.

BTW I note this interesting commit has just been merged to the kernel tree. jimbojr = James Adams, Director of Hardware at Pi Towers, so that is pretty much the horse's mouth.
The pin muxing info has been in https://github.com/raspberrypi/firmware ... .dts#L1317 for a while, and I know that works.
Between the two files you can get a pretty good idea of what is and isn't present by default on a CM3.
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Re: CM3 specs

Tue Aug 30, 2016 1:31 pm

jrychter wrote: Sigh. Well, this is a bit of a problem — I mean, in the hobby world, this is perfectly fine, but from what I understand the CM and the V2 cameras are supposed to be money-makers for the RPF, designed for the industrial world. Well the industrial world needs to plan ahead :-)
I think you have a valid point with regards to the CM3, but not with respect to camera. The new camera modules are a replacement for the old ones because the old sensor went out of production, so they're still a hobbyist/maker/educational device.
I don't understand the whole business with adapters on the CM I/O developer board. Cameras have a 15-pin 1mm pitch FFC connector, so why not just stick to that? It's not like the I/O dev board doesn't have enough space.
i have been--possibly wrongly--assuming that the choice of the smaller camera and display connectors on the dev carrier board was a matter of space on the board edge. That was certainly the case with the Pi Zero, which uses the same--smaller--connectors. I do recall reading, early on when the special Pi Zero camera cables weren't readily available, that someone connected a Pi Zero to a camera using the adapter board from the CM dev kit. I don't know if the converse experiment has been done (using the Pi Zero camera cable with a dev kit), but I'd be rather surprised if that hasn't been done by now. The point of all that being that I'm not at all sure that the CM is "wedded" to the smaller connector.

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Re: CM3 specs

Wed Aug 31, 2016 11:06 am

W. H. Heydt wrote:
jrychter wrote: Sigh. Well, this is a bit of a problem — I mean, in the hobby world, this is perfectly fine, but from what I understand the CM and the V2 cameras are supposed to be money-makers for the RPF, designed for the industrial world. Well the industrial world needs to plan ahead :-)
I think you have a valid point with regards to the CM3, but not with respect to camera. The new camera modules are a replacement for the old ones because the old sensor went out of production, so they're still a hobbyist/maker/educational device.
I don't understand the whole business with adapters on the CM I/O developer board. Cameras have a 15-pin 1mm pitch FFC connector, so why not just stick to that? It's not like the I/O dev board doesn't have enough space.
i have been--possibly wrongly--assuming that the choice of the smaller camera and display connectors on the dev carrier board was a matter of space on the board edge. That was certainly the case with the Pi Zero, which uses the same--smaller--connectors. I do recall reading, early on when the special Pi Zero camera cables weren't readily available, that someone connected a Pi Zero to a camera using the adapter board from the CM dev kit. I don't know if the converse experiment has been done (using the Pi Zero camera cable with a dev kit), but I'd be rather surprised if that hasn't been done by now. The point of all that being that I'm not at all sure that the CM is "wedded" to the smaller connector.
The CM isn't married to any sort of connector except the DIMM that connects it the carrier board. You can use whatever connectors you like on the carrier!
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jrychter
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Re: CM3 specs

Thu Sep 01, 2016 8:12 am

Thanks for all the tips. I have already sent an E-mail to the foundation (no response so far) and will try other means of contact.

I looked at the git commit and I like the "i2c2_iknowwhatimdoing" line :-)

I think I also now understand why the 22-pin connectors with the weird converters appeared on the CM I/O board (to expose the 4 CSI lanes available on one of the CSI interfaces).

One more note of explanation: when I wrote about camera changes, I meant not the switch to the IMX219 sensor (which is a great move), but the rumored possibility of newer camera modules having a 0.5mm pitch FFC connector. And @jamesh: I know I can use whatever connectors I like on the carrier board. I use 1mm pitch FFC connectors right now. My point was that once you get into production, there are pipelines, lead times, stock, and other real-world problems, and if the cameras switched to a 0.5mm pitch FFC, I'd have to redesign the carrier boards (which isn't that big of a deal), and also manage the whole transition (which is a big deal).

Anyway, most of my questions that I asked in the initial post still stand. I can hazard a guess that there will be no wifi, but I still don't know the power budget required, nor if a better in-factory programming solution will be available. I will try contacting gsh and asking nicely.
--J.
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Re: CM3 specs

Thu Sep 01, 2016 8:54 am

jrychter wrote:Thanks for all the tips. I have already sent an E-mail to the foundation (no response so far) and will try other means of contact.

I looked at the git commit and I like the "i2c2_iknowwhatimdoing" line :-)

I think I also now understand why the 22-pin connectors with the weird converters appeared on the CM I/O board (to expose the 4 CSI lanes available on one of the CSI interfaces).

One more note of explanation: when I wrote about camera changes, I meant not the switch to the IMX219 sensor (which is a great move), but the rumored possibility of newer camera modules having a 0.5mm pitch FFC connector. And @jamesh: I know I can use whatever connectors I like on the carrier board. I use 1mm pitch FFC connectors right now. My point was that once you get into production, there are pipelines, lead times, stock, and other real-world problems, and if the cameras switched to a 0.5mm pitch FFC, I'd have to redesign the carrier boards (which isn't that big of a deal), and also manage the whole transition (which is a big deal).

Anyway, most of my questions that I asked in the initial post still stand. I can hazard a guess that there will be no wifi, but I still don't know the power budget required, nor if a better in-factory programming solution will be available. I will try contacting gsh and asking nicely.
The camera cable isn't going to change - there are 10M ish boards out there with that camera connector, changing would mean those 10M boards could not connect to the camera. Which would be mad!
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Re: CM3 specs

Thu Sep 01, 2016 9:45 am

jrychter wrote:I looked at the git commit and I like the "i2c2_iknowwhatimdoing" line :-)
That's the same as all the other platforms - see https://github.com/raspberrypi/linux/issues/1028
i2c2 is used by the HDMI interface to read the EDID information, so to use it for other purposes you need to know what you're doing. Rewrite the EDID incorrectly on your monitor and you've effectively bricked the monitor :shock:
jrychter wrote:Anyway, most of my questions that I asked in the initial post still stand. I can hazard a guess that there will be no wifi, but I still don't know the power budget required, nor if a better in-factory programming solution will be available. I will try contacting gsh and asking nicely.
I'd say that you've got most of the answers already via a low level of deduction. I am privy to some extra knowledge that I can't say publicly, but what I can say is:
* Will there be on-board WiFi+Bluetooth?
Read the device tree setup - no reference to Wifi/Bluetooth.
The intent of the CM is to expose as much functionality of the SoC as possible, so adding anything else on the CM itself would reduce features available via the SODIMM connector, and break backward compatibility (you may have used an now unavailable line).
* Do we still get two synchronized CSI cameras with good software support, like on the CM1?
Yes. Sync has never been perfect as they are on independent oscillators, but pretty much synced.
* Will there be a better solution for factory programming than a USB MUX and an USB port just for this purpose?
The SODIMM pinout is fixed, so there is no easy way to change the external behaviour, and it has to be backwards compatible with CM1. BCM2837 does add the options of USB MSD and network boot (only off smsc951x network interfaces), so that may provide alternative options.
* Are power requirements similar?
Slightly more current on (from other threads) the VBAT line. I don't have numbers on it.
* Should we expect having to redesign our boards when switching from CM1 to CM3?
No (as long as the regulators can deliver sufficient power)

If you get no answers from gsh then I need to contact him in the next couple of days anyway and may hassle him on your (and others) behalf. I don't see there being anything commercially sensitive in the required power figures for CM3.
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jrychter
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Re: CM3 specs

Thu Sep 01, 2016 10:56 am

6by9 wrote:
jrychter wrote:I looked at the git commit and I like the "i2c2_iknowwhatimdoing" line :-)
That's the same as all the other platforms - see https://github.com/raspberrypi/linux/issues/1028
i2c2 is used by the HDMI interface to read the EDID information, so to use it for other purposes you need to know what you're doing. Rewrite the EDID incorrectly on your monitor and you've effectively bricked the monitor :shock:
Yes — I actually like that line for two reasons, one is that it looks great :-) and another is that I *do* know what I'm doing and I could make use of i2c2 if I could expose it somewhere.
6by9 wrote:If you get no answers from gsh then I need to contact him in the next couple of days anyway and may hassle him on your (and others) behalf. I don't see there being anything commercially sensitive in the required power figures for CM3.
Thanks for all your answers. Yes, I suspected most of those, but it's good to see some confirmation. When designing hardware, I'd rather not stick to hunches and gut feelings. The only thing which I need right now is the power requirements, and I'll happily wait for the CM3 to appear (well, I'll wait until the end of the year at least).

Thanks!
--J.
Founder at PartsBox: https://partsbox.io/ (keep track of your electronic components)

nsbrown93
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Re: CM3 specs

Fri Sep 16, 2016 6:14 am

jrychtr: We are in a similar situation at our company. I posted this awhile back which may have some useful information that wasn't already shared. PM if you want to discuss at all since we're in the same boat.

viewtopic.php?f=98&t=141306&p=935457#p935457

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