I have found at some places, especially:

Raspberry Pi Forums

eLinux RPi Hardware page

the following wording:

S2: DSI interface. 15-pin surface mounted flat flex connector (possibly no-fit) S5: MIPI CSI-2 interface. 15-pin surface mounted flat flex connector (possibly no-fit).

P2: 8-pin 2.54 mm header expansion (header not fitted on Revision 2.0 boards), providing GPU JTAG (ARM11 pinout, pin 7 is nofit for locating)

For a non-English reader this is not 100% clear. Could you please tell me what it means?

  • 2
    \$\begingroup\$ You may also see the word "omit" used, which might be clearer to you. \$\endgroup\$ – Martin Mar 28 '13 at 13:49

This must be British. For them "fit" means something like what we would call "install". For us, "fit" means how well something fits, meaning how good it is at mechanically going into the right mounting holes or whatever, or how effective it is overall in the role it is being used in.

In this case "no-fit" means "do not install". This is often done when a part may be useful for original testing in the lab. Once the product has been verified, the part is of no use anymore. Instead of respinning the PCB, you leave the pads there but just not install the part during manufacturing.

The same PCB can be used to build different variants of a product depending on which parts are installed or not. In one case I had a product that was to be sold with either a RS-232 or CAN interface. Since space was tight, I re-used the PCB area for the CAN driver chip and the RS-232 chip. The pads of the two chips sortof overlapped such that only one could be installed at a time. There were some other parts that had to be installed or not depending on the variant being built.

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    \$\begingroup\$ Your first paragraph is actually rather obnoxious. Please bear in mind that 95% of people on this planet are not American and avoid setting up explicit "us" versus "them" dichotomies based on the assumption that all of your readers are in the 5%. They're not. \$\endgroup\$ – David Richerby Sep 14 '14 at 11:18

Other common terms used are "no placement" (NP) or "do not place" (DNP) but "no fit" would fall into the same category. It means the circuit board (PCB) has pads where a connector may be placed, but when you receive the board it won't have a connector installed. It will be up to you to source the connector and install it youself if you require it.

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    \$\begingroup\$ I've also seen "not fitted", "not stuffed" and DNP (do not populate). \$\endgroup\$ – Adam Lawrence Mar 28 '13 at 16:02
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    \$\begingroup\$ Also DNS - do not stuff. I use DNP for do not populate, it's the most common in my experience. \$\endgroup\$ – Jeanne Pindar Mar 28 '13 at 16:26
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    \$\begingroup\$ Also DNI - do not install. \$\endgroup\$ – Ben Jackson Mar 28 '13 at 19:49
  • \$\begingroup\$ Also, "DNL" Do Not Load. \$\endgroup\$ – KyranF Apr 25 '14 at 10:04

"No fit" is an instruction from the designer to the manufacturer: do not fit this component. It means the connector won't be there but can be fitted later.

  • 3
    \$\begingroup\$ That's a rather circular definition when the problem is not understanding "fit" in the first place. That is one of those "english" words that varies significantly with location. \$\endgroup\$ – Olin Lathrop Mar 28 '13 at 13:40

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