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15 to 22 pin fpc connector adapter pinout?

Posted: Wed Aug 03, 2016 6:40 pm
by kuruki
Hi,

I want to create a small PCB adapter for the 22 pin fpc connector found on the Raspberry Pi zero. I read that the connector is the same as on the compute module and particularly on the Camera/Display adapter boards.

From the files found there, here is the schematic of the camera adapter which does the same thing as I want to replicate:

Image

There we can see that pins 19,16,13,10 of the 22pin connector, are attached to the CAM_GND signal. However, judging by the raspberry pi zero camera cable, they are seemingly not.

Image

I want to create a single layer PCB adapter however to do that, it is not so convenient to connect pin 19 of the 22pin connector to CAM_GND. So my question is, does that matter, since this pin seems to be left unconnected on the camera cable anyway?

Re: 15 to 22 pin fpc connector adapter pinout?

Posted: Wed Aug 03, 2016 8:02 pm
by aBUGSworstnightmare
Why not simply connect them (route trace under connector)? This works even on a single layer PCB.
Yes, you don't need them for the ZERO. They are shielding the CSI signals and not used for carrying power supply current since the camera doesn't draw much current.

What is the adapter used for? Extending the cable lenght?

Re: 15 to 22 pin fpc connector adapter pinout?

Posted: Wed Aug 03, 2016 9:43 pm
by 6by9
Pins 11&12, and 14&15 are CSI data lanes 2&3 if 4 lanes are in use (only applicable on CAM1). They are therefore high speed signals and it is good practice to surround any high speed signals with a ground for EMC reasons.
The Pi Zero only brings out data lanes 0&1, so therefore having the ground around 11&12 and 14&15 is redundant as there is no signal on those pins.

Re: 15 to 22 pin fpc connector adapter pinout?

Posted: Wed Aug 03, 2016 9:52 pm
by kuruki
aBUGSworstnightmare wrote:Why not simply connect them (route trace under connector)? This works even on a single layer PCB.
There absolutely is no good practical reason. :lol: :D
They are shielding the CSI signals and not used for carrying power supply current since the camera doesn't draw much current.
I also thought they were grounding them just as a good practice on the boards. I guess it won't hurt if one of them doesn't. :) Here's how mine should look like:
Image
What is the adapter used for? Extending the cable lenght?
Hmm, not really, it's first and foremost an experiment. :P I want to use the board as an 22-to-15 pin adapter and insert it in the FPC connector on the Zero. I am making it as thin as I can, at a reasonable price (~1$ per board), which is 0.4mm. Whether this is a good idea or not, we shall see soon! :mrgreen:
The goal is to create something cheaper than the 4£ (+ shipping) RPi zero camera cable that is currently being sold, as I find the price fairly expensive. This would be particularly useful to the ones who already own an RPi camera and 15pin ribbon cables, like myself. :)
6by9 wrote:Pins 11&12, and 14&15 are CSI data lanes 2&3 if 4 lanes are in use (only applicable on CAM1). They are therefore high speed signals and it is good practice to surround any high speed signals with a ground for EMC reasons.
The Pi Zero only brings out data lanes 0&1, so therefore having the ground around 11&12 and 14&15 is redundant as there is no signal on those pins.
Yay, a new answer while I was responding to the previous one! Very well explained, thanks a lot! :) What do you think of the idea above by the way? Do you think it's feasible and makes sense?

Re: 15 to 22 pin fpc connector adapter pinout?

Posted: Fri Aug 05, 2016 10:27 am
by aBUGSworstnightmare
kuruki wrote:Hmm, not really, it's first and foremost an experiment. I want to use the board as an 22-to-15 pin adapter and insert it in the FPC connector on the Zero. I am making it as thin as I can, at a reasonable price (~1$ per board), which is 0.4mm. Whether this is a good idea or not, we shall see soon!
Well, nice idea. Never tried to insert an PCB into an FFC connector, but looks like your chances are not too bad: http://www.molex.com/pdm_docs/sd/545482271_sd.pdf

Don't expect too much mating cycles in such a case...


Note: http://m.aliexpress.com/item/32580388271.html
Designing a PCB with two FFC connectors might be simpler

Re: 15 to 22 pin fpc connector adapter pinout?

Posted: Mon Aug 08, 2016 3:21 pm
by sej7278
just got a couple of samples from molex - part number 0545482271 isn't the same as on my pi zeroes. the black retaining connector (that snaps off easily!) has curly legs on it to lock it in place on the samples, well on my zeroes its just a straight pin. even the cream plastic bit is pretty mismatched.

i managed to get the samples to fit if i snipped the curly bit off the legs, but it doesn't stay in well then.

i have ordered some generic chinese 0.5m pitch bottom connector 22 pin fpc parts to see if they fit, they do look like they have straight legs. given how fragile the connector is, 10 is probably just about enough!
zero_molex33.jpg
zero_molex33.jpg (55.26 KiB) Viewed 14966 times

Re: 15 to 22 pin fpc connector adapter pinout?

Posted: Mon Aug 08, 2016 4:50 pm
by aBUGSworstnightmare
sej7278 wrote:just got a couple of samples from molex - part number 0545482271 isn't the same as on my pi zeroes. the black retaining connector (that snaps off easily!) has curly legs on it to lock it in place on the samples, well on my zeroes its just a straight pin. even the cream plastic bit is pretty mismatched.

i managed to get the samples to fit if i snipped the curly bit off the legs, but it doesn't stay in well then.

i have ordered some generic chinese 0.5m pitch bottom connector 22 pin fpc parts to see if they fit, they do look like they have straight legs. given how fragile the connector is, 10 is probably just about enough!
zero_molex33.jpg
Why does it need to be the same? As long as the pin pitch is correct (0.5mm) and the contacts are on the right side you can pretty much use every 0.5mm pitch connector. I prefer using FH28 (if possible) since the have a nice lid (flaps and not slides). It's your own design, so you can choose whatever you want too.
Maybe worth to have a look at the CM BOM?

Re: 15 to 22 pin fpc connector adapter pinout?

Posted: Tue Aug 09, 2016 4:51 pm
by sej7278
aBUGSworstnightmare wrote:Why does it need to be the same? As long as the pin pitch is correct (0.5mm) and the contacts are on the right side you can pretty much use every 0.5mm pitch connector. I prefer using FH28 (if possible) since the have a nice lid (flaps and not slides). It's your own design, so you can choose whatever you want too.
Maybe worth to have a look at the CM BOM?
i'm talking from a repair perspective, not an own build one. the cm/zero part is oft quoted as 0545482271, but that's plainly wrong.

and yes i agree, the flap rather than drawer connectors are much better.

Re: 15 to 22 pin fpc connector adapter pinout?

Posted: Wed Aug 10, 2016 5:23 am
by aBUGSworstnightmare
sej7278 wrote:the cm/zero part is oft quoted as 0545482271, but that's plainly wrong.
Where do you have this information from? When looking at the official design data for the Compute Module camera/display adapter board (CMCDA) here https://www.raspberrypi.org/documentati ... PUBLIC.zip , referring to the BOM - it clearly states:
Part 54548-2271
Manufacturer Molex
Manuf. Part # 54548-2271

Yes, your right! This is not the part used on the Zero, but...I'm pretty sure most of the people will ruin their Zero when trying to replace the ZIF connector.

Re: 15 to 22 pin fpc connector adapter pinout?

Posted: Mon Aug 15, 2016 8:53 pm
by kuruki
FYI the 0.4mm PCB will fit in the FPC connector! Just received them today. Now only need to solder the other connector and see if the whole thing works. :)

Re: 15 to 22 pin fpc connector adapter pinout?

Posted: Tue Aug 16, 2016 9:30 am
by aBUGSworstnightmare
kuruki wrote:FYI the 0.4mm PCB will fit in the FPC connector! Just received them today. Now only need to solder the other connector and see if the whole thing works. :)
Keep us posted!