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Posts: 79 | Thanked: 719 times | Joined on May 2014 @ Buenos Aires, Argentina
#11
This is a little background document I wrote to help with choosing the Hackerbus connectors:

http://neo900.org/stuff/papers/hdr.pdf

It contains tables of headers and receptacles that are available at Digi-Key, with the parameters necessary for height-matching sets of connectors. For now, it only covers the sort of connectors we were considering for Hackerbus, i.e., 1.27 mm (50 mil) headers, single or dual row, male through-hole or female SMT.

It's not necessary to read this document to understand the Hackerbus interface (that's why I'm posting this here and not in the thread for "major" announcements), but it may be useful for someone trying to solve a similar header-matching problem.

This specific version is at
http://neo900.org/stuff/papers/hdr-20150225.pdf

The source can be found at
http://neo900.org/git/?p=misc;a=tree;f=hdr

To do the actual matching, I used this script to read the tables from the LaTeX source and look for suitable combinations:

http://neo900.org/git/?p=misc;a=blob;f=hb/dbq.pl

- Werner

[ Edit: 1.27 mm is 50 mil, not 100. ]

Last edited by wpwrak; 2016-01-28 at 21:49.
 

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Posts: 79 | Thanked: 719 times | Joined on May 2014 @ Buenos Aires, Argentina
#12
A little update to the header selection document: we looked at a few options for improving the Hackerbus connections, and to help with this discussion, I added female through-hole 1.27 mm (50 mil) single row parts.

Link to the latest version of the document:
http://neo900.org/stuff/papers/hdr.pdf

This specific version:
http://neo900.org/stuff/papers/hdr-20160126.pdf

Source:
http://neo900.org/git/?p=misc;a=tree;f=hdr

- Werner
 

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#13
The mechanical design of Neo900 is affected by numerous parameters that originate from N900, and that we have to determine by measuring case and other parts. So far, we did many of these measurements in an ad hoc fashion. This sometimes created the problem that, when coming back to some part of the design after a few months, it wasn't quite clear where certain parameters came from, and we often had to repeat measurements to confirm these parameters.

Two topics we're currently looking into, the exact placement of the second SIM card holder and improving the mechanical stability of the spacer frame, promised to yield a number of new parameters to keep track of, and I didn't feel too comfortable about continuing with the ad hoc approach for them.

There is now a better way: since many measurements come from the case scans, I've now added the ability to produce annotated "screenshots" to the program taking the measurements, and used them to document the key parts of the vertical stacking of Neo900:

https://neo900.org/stuff/werner/stacking/

The annotations are for "hands-on" use and aren't very pretty, but they should allow to see quickly what is going on. As often happens with this sort of endeavors, we discovered a surprising detail of how Nokia designed the spacers between the display module to the PCB.

The ingredients for generating the above page are in the repository:

https://neo900.org/git/?p=misc;a=tree;f=stacking

- Werner
 

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Posts: 79 | Thanked: 719 times | Joined on May 2014 @ Buenos Aires, Argentina
#14
Hellekin implemented stricter content security policy on neo900.org: to limit opportunities for cross-site scripting attacks, we now avoid inline CSS and JavaScript, and serve assets from our server only.

For context:
http://content-security-policy.com/

As a consequence, the block diagrams, that enthusiastically used every little feature that's now discouraged, stopped working for a few days. We've fixed it now.

Please note that, if you're using a localized copy, that the procedure for generating it has changed, too. The updated instructions are in:
http://neo900.org/git/?p=misc;a=blob;f=block/README

- Werner
 

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Posts: 79 | Thanked: 719 times | Joined on May 2014 @ Buenos Aires, Argentina
#15
Another small update of the header selection document: it now lists a few male 2.54 mm dual-row through-hole headers, as candidates for the connection between v2 and BB-xM. I also clarified some details about pin geometry.

Link to the latest version of the document:
http://neo900.org/stuff/papers/hdr.pdf

This specific version:
http://neo900.org/stuff/papers/hdr-20161201.pdf

Source:
https://neo900.org/git/misc/tree/hdr

- Werner
 

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