What's With These Inconsistent Pins? - Page 1
Forum section: electronics / beginners

author: Max Holdcroft
author_rank: Contributor
timestamp: May 27, 2024, 08:36:33 am
content: I'm looking at the datasheet for the ISP_1507 BLE module. In the reference schematic for the module, they use a 10 pin 0.5mm pitch FFC, but for the schematic I have the pins are all different. In the example schematic, they have two ground pins, but in my schematic there aren't any, but there IS an additional "anchor" pin? What is this?I appreciate any help!Max

author: Gyro
author_rank: Super Contributor
timestamp: May 27, 2024, 09:12:28 am
content: Please stop creating a new thread foreveryquestion about this module. That's not how this forum works and will put you on the wrong side of the Mods!

author: pcprogrammer
author_rank: Super Contributor
timestamp: May 27, 2024, 09:28:52 am
content: Quote from: Gyro on May 27, 2024, 09:12:28 amNot just the mods.Also the same programming connector is attached here, but I'm not sure if there still is an issue with attachments getting mixed up.I know the OP is young according to his profile, but when you want help you need to be more precise.@Max Holdcroft you mention "my schematic", so where is that one? Provide as much information as possible when asking for help. We are not mind readers, nor do we have crystal balls.And like Gyro pointed out just do it in a single thread, and when you don't get the answers you are looking for, don't think that trying again in a slightly different form in a new thread will get you that answer.

author: Gyro
author_rank: Super Contributor
timestamp: May 27, 2024, 09:41:00 am
content: I hadn't realised that the OP was so young. @Max, yes please keep everything in the same thread, then people have a much better chance of 'connecting' your questions.

author: pcprogrammer
author_rank: Super Contributor
timestamp: May 27, 2024, 03:24:59 pm
content: Quote from: Max Holdcroft on May 27, 2024, 08:36:33 amI read your post again and challenge you to think about this last bit yourself. Do some searching online to find pictures of the bare connectors and imagine what this anchor pin would be.Here is a starter.https://www.molex.com/en-us/products/connectors/ffc-fpc-connectors

author: coromonadalix
author_rank: Super Contributor
timestamp: May 27, 2024, 05:42:09 pm
content: even posted herehttps://forum.allaboutcircuits.com/members/max-holdcroft.984775/#latest-activity

author: xvr
author_rank: Frequent Contributor
timestamp: May 27, 2024, 05:51:26 pm
content: Hirose connector has 2 pins connected to shield (?) inside it. In original schematic there are pins 11 & 12 (with gound connected to them). I thgink that Anchor is a one of these pins (one only one - I don't know)

author: pcprogrammer
author_rank: Super Contributor
timestamp: May 27, 2024, 06:28:39 pm
content: Quote from: xvr on May 27, 2024, 05:51:26 pmAnd that more or less is the same response as what he got on the other website, and still not grasping the concept that these are there for mechanical strength and possible shielding.A lot of these SMD connectors have additional "pins" to hold them down on the board. Some use through hole clips for even stronger bonds. That is what I tried to have him find out by himself with the challenge.The fact that a symbol in a schematic editor only shows one pin does not mean there is only one on the actual foot print for it. But for that it is needed to learn the basics of everything one wants to do, and not jump in the deep end of the pool without flotation devices.You want to do schematic design with a software packet, learn about how the packet works, what the symbols do, and how they are created, but first learn what the electronics components are for and how they work.But that advice just seems to shoot past him.

author: Terry Bites
author_rank: Super Contributor
timestamp: May 31, 2024, 06:59:42 am
content: Connector companies list their products by number of available connections and it's their "as described" footprint that ends up in the CAD.In this case 10 connections to a 10-way FPC jumper.There is not really a pin 11 or 12, they are actually mechanical mounting points.Ordinarily the mechanical mounts would be soldered to small PCB pads.Thats fine inside a finished product where the connector just gets touched once or twice.They are a weak point and often the connector will break away destroying the PCB as it goes.To make a stronger mount for an evaluation PCB they have been soldered to a large area of copper groundplane.There's usually a bit (plenty) of fudge factor in PCB designs. Don't panic.They will have just numbered those as pins to force the CAD into thinking they are an actual signal connection. And that’s it.Learn a bit about how signal nets interconnect component footprints in PCB CAD.

author: pcprogrammer
author_rank: Super Contributor
timestamp: May 31, 2024, 08:09:06 am
content: These connectors are not good for multiple insertion cycles, so kind of a bad choice of the experiment kit designer to use them.From the Hirosewebsiteonly 20 mating/unmating cycles:

author: Terry Bites
author_rank: Super Contributor
timestamp: May 31, 2024, 04:11:41 pm
content: Too right.So many connectors have very low mating cycle numbers.RJxx among them.

author: tooki
author_rank: Super Contributor
timestamp: June 01, 2024, 12:27:49 pm
content: But that is totally OK for many applications. Low mating cycle connectors are for assembly and rare repair or maintenance. Medium mating cycle connectors are for things that get reconnected now and then. High mating cycle connectors are for long-lived devices that are reconnected constantly.No sense in adding the bulk and cost of high mating count connectors for things that simply do not need it.It is, of course, incumbent on the designer to choose a connector with the appropriate mating cycles for the application.In this case, I don’t think that was a wise choice, but it could be OK if the envisioned use was to keep the cable inserted in the programmer, and only disconnect the device end, i.e. to use one programmer to program many devices.Modular (RJ-xx) jacks are typically rated for hundreds of cycles, so an entire order of magnitude more than the Hirose FFC here.

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 01, 2024, 12:35:13 pm
content: Quote from: tooki on June 01, 2024, 12:27:49 pmIs a possibility, but these cables are not so good either and can also wear out on to many connect/disconnect cycles.