Author Topic: User Configuration without DIP Switches or Header Pins  (Read 5532 times)

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Offline NivagSwerdnaTopic starter

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User Configuration without DIP Switches or Header Pins
« on: July 25, 2020, 11:03:26 pm »
I often have the requirement to make a PCB that has to be configurable.... I have taken to creating a small footprint that allows the user to create a solder bridge for a selection of setting



to be honest this doesn't work particularly well... the solder doesn't pool well to make a connection. 

An obvious alternative would be a set of DIP switches or Headers that allow a jumper pin but these are quite large

Any suggestions on making end-user configuration easy?  (I am starting to wonder if my JP footprint is unreasonable due to being 0603 sized anyway... might not be feasible for anyone without a microscope?)
 

Offline Bassman59

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Re: User Configuration without DIP Switches or Header Pins
« Reply #1 on: July 26, 2020, 12:32:07 am »
"End user" configuration means no soldering!

What are you configuring? That might help us give a good suggestion.
 

Offline TheMG

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Re: User Configuration without DIP Switches or Header Pins
« Reply #2 on: July 26, 2020, 12:52:09 am »
Some context would be helpful! What kind of thing is this configuring? Does the board include a microcontroller? What sort of maximum size constraint are we dealing with?
 

Offline bson

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Re: User Configuration without DIP Switches or Header Pins
« Reply #3 on: July 26, 2020, 05:46:50 am »
How about 50mil jumpers on a small 50mil SMT pin header?  50mil is pretty small...

Edit: a suitable header is Samtec FTSH-1nn-01-F-DV where 'nn' is the number of pins per row.  (E.g., nn=02 for 2 pins per row, for 4 total.)  FTS is the same, lower profile.

(Yes, I know you didn't want headers or jumpers, but they do work nicely! :))
« Last Edit: July 26, 2020, 06:08:42 am by bson »
 
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Offline Benta

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Re: User Configuration without DIP Switches or Header Pins
« Reply #4 on: July 26, 2020, 10:06:58 am »
Easiest and cheapest is an array of vias. Drill out the connections you don't want.
Much faster than solder bridges.

 

Online Siwastaja

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Re: User Configuration without DIP Switches or Header Pins
« Reply #5 on: July 26, 2020, 10:17:47 am »
Easiest and cheapest is an array of vias. Drill out the connections you don't want.
Much faster than solder bridges.

This can be only modified once, from '1' to '0'. If this is acceptable, I would suggest using a very thin trace between fat pads, with no ground plane directly underneath, so that you can cut the trace with a knife. Mark where to cut by adding a solder mask cutout region right at the trace.

But, it's too easy to accidentally remove the one bit you did not want to remove, especially if this "end user" isn't the assembler under your control.
 

Offline OM222O

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Re: User Configuration without DIP Switches or Header Pins
« Reply #6 on: July 26, 2020, 10:18:06 am »
If your application uses a micro, doing it via a MUX or switch IC through software is the best solution. Especially if you have an ESP that allows control via wifi. Otherwise a gang of dip switches is unfortunetly the best. If the configuration is one time only, cuttable traces are the best.
 

Offline Benta

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Re: User Configuration without DIP Switches or Header Pins
« Reply #7 on: July 26, 2020, 10:34:24 am »
Easiest and cheapest is an array of vias. Drill out the connections you don't want.
Much faster than solder bridges.

This can be only modified once, from '1' to '0'.
Inverting logic is the easiest thing in the world.

 

Online Siwastaja

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Re: User Configuration without DIP Switches or Header Pins
« Reply #8 on: July 26, 2020, 12:17:41 pm »
Easiest and cheapest is an array of vias. Drill out the connections you don't want.
Much faster than solder bridges.

This can be only modified once, from '1' to '0'.
Inverting logic is the easiest thing in the world.

Wat?

The problem is you can't revert your decision. (Or need bodge wire + soldering iron to do that.)
 

Offline tooki

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Re: User Configuration without DIP Switches or Header Pins
« Reply #9 on: July 26, 2020, 12:41:45 pm »
I often have the requirement to make a PCB that has to be configurable.... I have taken to creating a small footprint that allows the user to create a solder bridge for a selection of setting

(Attachment Link)

to be honest this doesn't work particularly well... the solder doesn't pool well to make a connection. 

An obvious alternative would be a set of DIP switches or Headers that allow a jumper pin but these are quite large

Any suggestions on making end-user configuration easy?  (I am starting to wonder if my JP footprint is unreasonable due to being 0603 sized anyway... might not be feasible for anyone without a microscope?)
Why not just use 0 ohm jumpers (i.e. 0 ohm resistors)? They’re a common way of doing it.

And if you really wanna get fancy, and happen to have a spare ADC pin on a microcontroller, you could use configuration resistors as a resistor divider, then measure the output voltage and configure based on that. That lets you use one fixed, preinstalled resistor plus a single configuration resistor to easily encode many different configurations.
 

Offline mikeselectricstuff

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Re: User Configuration without DIP Switches or Header Pins
« Reply #10 on: July 26, 2020, 12:43:27 pm »
TH pad that can be drilled out, plus a pair of semicircular pads that can be solder-bridged to re-connect

For one-time configuration, I've seen a product that had a number of small fingers on the PCB, with U-shaped traces on, which were snapped off as required

For solder-blobs, a pair of 0805 pads  with about a 0.5mm gap between them works well.
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Offline mikeselectricstuff

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Re: User Configuration without DIP Switches or Header Pins
« Reply #11 on: July 26, 2020, 12:47:42 pm »
And of course there are plenty of interactive methods using whatever switches and indicators you have available to store config in nonvolatile memory.
touchpads are basically free if you don't have any buttons, and a single LED would do if there are only a few options, indicating via flash count/lengths

This is something where you need to look at all your requirements to determine the best solution, e.g. do you need to be able to see the config when there is no power, can you (safely) power it for the user to do some sort of interactive process, what is the expected skill level of the person doing the config, could you use an external programmer box to do it etc. etc. etc.
And is a DIP switch/link set more expensive than the support costs of a more arcane method ?


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Offline mikeselectricstuff

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Re: User Configuration without DIP Switches or Header Pins
« Reply #12 on: July 26, 2020, 12:49:18 pm »
I often have the requirement to make a PCB that has to be configurable.... I have taken to creating a small footprint that allows the user to create a solder bridge for a selection of setting

(Attachment Link)

That's a really poor layout for solder-blobbing. Use a pair of semicircular pads,at least 2mm dia, so the natural surface tension of the solder forms a dome over the 2 pads.
Youtube channel:Taking wierd stuff apart. Very apart.
Mike's Electric Stuff: High voltage, vintage electronics etc.
Day Job: Mostly LEDs
 

Offline NivagSwerdnaTopic starter

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Re: User Configuration without DIP Switches or Header Pins
« Reply #13 on: July 26, 2020, 01:11:43 pm »
That's a really poor layout for solder-blobbing. Use a pair of semicircular pads,at least 2mm dia, so the natural surface tension of the solder forms a dome over the 2 pads.
That's what I was thinking; in my design the solder tends to run back down the traces... very annoying... I think even with my design it needs more solder mask.  I like the idea of semi-circular.
 

Offline NivagSwerdnaTopic starter

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Re: User Configuration without DIP Switches or Header Pins
« Reply #14 on: July 26, 2020, 01:14:46 pm »
Some context would be helpful! What kind of thing is this configuring? Does the board include a microcontroller? What sort of maximum size constraint are we dealing with?
One example...
I have a rather flexible ROM replacement board which fits in a 28 DIP package side... I need
3x Bank Selection JP2
3x Address Selection JP2
7x Mode selection JP1

JP2 is a jump that is either A or B; JP1 is either A or OPEN.

 

Offline NivagSwerdnaTopic starter

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Re: User Configuration without DIP Switches or Header Pins
« Reply #15 on: July 26, 2020, 01:19:43 pm »
Here's an example...


Now there are several things that don't work here... firstly the JP2 solder options don't flow very well... and secondly this really isn't a practical method for end users... it's just too small and fiddly. 

Oh... and I do need the end user to be able to change these. <- Critical requirement
« Last Edit: July 26, 2020, 01:26:04 pm by NivagSwerdna »
 

Offline NivagSwerdnaTopic starter

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Re: User Configuration without DIP Switches or Header Pins
« Reply #16 on: July 26, 2020, 01:25:12 pm »
50mil is pretty small...
...
(Yes, I know you didn't want headers or jumpers, but they do work nicely! :))
Maybe that is the answer.
 

Offline mariush

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Re: User Configuration without DIP Switches or Header Pins
« Reply #17 on: July 26, 2020, 02:04:58 pm »
The footprint kinda sucks for jumpers.
here's an  example ... click on the picture ... See J1..J4 : https://www.digikey.com/product-detail/en/newhaven-display-intl/NHD-0216XZ-FSW-GBW/NHD-0216XZ-FSW-GBW-ND/2165850

I've also seen basically the Yin Yang symbol - https://en.wikipedia.org/wiki/Yin_and_yang - with a bit of separation between the two sides ... a drop of flux and then a touch of solder and the surface tension would make good connection.

Another reasonable option would be the footprints usually used for calculator and keyboard keys... something as simple as a U and E shape with the - between the U 's traces.
ex a simplified version of this : https://electronics.stackexchange.com/questions/231293/studying-the-pcb-of-a-70s-calculator-what-were-they-thinking
or this : scroll down : https://www.petervis.com/Calculators/sharp-el-506h/sharp-el-506h.html

For a one time thing you could have 0 ohm resistors / jumper links ... make square/rectangular cutout in the pcb just big enough for the body of a resistor and put smd pads on the edges of the cutout ... have wire links or resistor across the hole in the pcb with leads soldered to the pads ... end user can just get scissors and cut the jumper link or resistor off.

like people above told you ... you have 50mil (1.27) jumpers, you have 2 mm jumpers and headers, there's options.
 
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Offline phil from seattle

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Re: User Configuration without DIP Switches or Header Pins
« Reply #18 on: July 26, 2020, 02:23:35 pm »
I use both header/jumpers and solder connections (semi circular - 6 mil gap). dip switches take up too much space (and are so 1970s).  The solder jumpers can be put on the bottom of a PCB so they are kind of "free" but at the cost of losing some users. I sell boards that require soldering so it's not a problem for my customers. 0 ohm resistors are basically the same as jumpers though larger and require a part - that's why I prefer jumpers.

But, frankly, if you are targeting customers that can't solder, you probably should go a different direction - some sort of soft configuration.
« Last Edit: July 26, 2020, 02:26:03 pm by phil from seattle »
 
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Offline NivagSwerdnaTopic starter

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Re: User Configuration without DIP Switches or Header Pins
« Reply #19 on: July 26, 2020, 04:01:34 pm »
some sort of soft configuration.
I wonder what the least overhead soft configuration would be... I could add a very cheap small microcontroller to hold config (maybe not on the example above but on more complex designs)... but still would need some simple programming tool for the end user...
 

Offline Benta

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Re: User Configuration without DIP Switches or Header Pins
« Reply #20 on: July 26, 2020, 04:32:19 pm »
I see you already use the leadframe pins, which are spring loaded (if you have the right size).

How about placing pads on both sides of the PCB on the end edges, snip off the pins of your leadframe and slide the remaining "U-clip" onto there as jumper?
 


Offline ebclr

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Offline bson

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Re: User Configuration without DIP Switches or Header Pins
« Reply #23 on: July 26, 2020, 07:07:08 pm »
If you use right angle, low profile, single row headers then you should be able to fit jumpers close to flat against the board.
 

Offline NivagSwerdnaTopic starter

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Re: User Configuration without DIP Switches or Header Pins
« Reply #24 on: July 26, 2020, 07:58:06 pm »
1.27 mm dipswitchs are smaller than your pads

https://www.mouser.com/Electromechanical/Switches/DIP-Switches-SIP-Switches/_/N-5g2s?P=1z0x3yz
These are nice but I think that since they are only ON or OFF that would mean I need quite a few since a lot of my configuration is A-B or B-C rather than A-B or OPEN?
 


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