Help with Let's Split not recognizing slave side

[WallofYawn]

First keyboard I've built, first anything I've soldered. Been at this problem for nearly two weeks.

You've heard this one before... I posted about this same issue over a week ago here.

Since then, I have replaced both TRRS jacks, the TRRS cable, flashed the default firmware to both Pro Micros... And nothing has changed. Slave half never registers keypresses but shows the same LEDs as the master.

Below is a gallery and then two individual pictures showing LED status and my jumpered TRRS connection since I lifted a pad desoldering.

https://imgur.com/a/aXrXu
https://imgur.com/a/jiNgk
https://imgur.com/a/ImmH9


I have a multimeter on the way, it should be here today. I hope it's something simple like voltage drop between halves. This post is mainly a brainstorming session to get fresh eyes on this.


Couple additional questions that I can't find answers to... When using a multimeter to check voltage between halves, am I checking the GND and VCC on the same Pro Micro on each half? Or am I checking GND to GND/VCC to VCC across halves? I'm new to all this, I guess maybe I should do more reding about electronics. Anyway, if anybody can shed some light, that would be great. Thanks.

[crystalhand]

Does each half work independently of each other?

You want to check the gnd and vcc for the slave half.  You could theoretically use the gnd on the master side but that adds complication.  You can also try a continuity test between the gnds on each half.


As a test you can solder a temp connection between the two halves.  There only really needs to be 3 connections between the two halfs gnd, vcc, and data. I cant recall exactly what pin the data is for lets split.

[jimirolln]

that board looks ruff my dude...i can't tell from the pic but diodes only run one way...i am sure you know that...it is possible however that you may have got the orientation on the slave half wrong...i am not saying you did that...just that it is a possibility

i would like to suggest that you pause this project where it is...put it on the back burner so to speak...and order another set of ls v2 boards
if it were any other project i wouldn't say that but for 9 bucks you can't go wrong...also will give you a chance to up g the controller

check the red it:  https://www.reddit.com/r/olkb/comments/87uo3l/a_proton_c_companion_for_split_boards/

the smaller is the electron...as opposed to two pro micros...its funny...this is the second time i've posted this today...it's really cool tho
i hope jack does a split planck with this incorporated into the pcb architecture...i am doing a ls v2 build myself and considered waiting for that...but as i mentioned...for 9 bucks you really can't go wrong...and the silk screening is sick...i am going to do the blue pcb on gsf dsa blanks and do some extra getto no plate...and either just some bump onz to the bottom of the pcb or some plug stands...not to sure yet

[jimirolln]

just in case...here is a link...it's only 20...and on top of that i don't like the gun handle ds stations
https://www.amazon.com/Tenma-21-8240-Vacuum-Desoldering-Iron/dp/B008DJRYIG/ref=pd_rhf_sc_p_img_1?_encoding=UTF8&psc=1&refRID=EP1XBEFCRVFJTGCW6N9B

[WallofYawn]

What's rough about it?

I followed the Overly Verbose Guide to Building a Let's Split to the T. Diodes all go the right way. I checked and double checked and then triple checked. Both pro micros get power and both boards are exactly the same as seen here https://camo.githubusercontent.com/c3fbe0ebbd7405ad6eba2dceaad085f94b35ad0e/687474703a2f2f692e696d6775722e636f6d2f72346b4d4253462e6a7067. I mean ****, the soldering job even looks roughly the same... No cold joints, no solder bridges (at least ones that aren't supposed to be there). The desoldering job put an extra amount of flux everywhere, but that's par for the course.


Here's both sides for reference https://imgur.com/gallery/8sdMI

[WallofYawn]

Does each half work independently of each other?

You want to check the gnd and vcc for the slave half.  You could theoretically use the gnd on the master side but that adds complication.  You can also try a continuity test between the gnds on each half.


As a test you can solder a temp connection between the two halves.  There only really needs to be 3 connections between the two halfs gnd, vcc, and data. I cant recall exactly what pin the data is for lets split.

I've run connections directly between the two Pro Micros and had it working. Which is why I then desoldered the whole board and replaced both TRRS jacks and the TRRS cable, but still no love.

And yes, each half works independently of each other with the slave side being a mirror of the master.

[jimirolln]

my bad...not ruff...it looks fine

i looked at it tryna come up with something for a minute...i got nothing...technical support isn't my thing...and my social skills are garbage...i didn't and don't mean to offend you...i feel your pain...don't get frustrated...zen budda this thing out

get another ls v2...do it again...don't give up on this one...but don't let it stunt your shine

[WallofYawn]

my bad...not ruff...it looks fine

i looked at it tryna come up with something for a minute...i got nothing...technical support isn't my thing...and my social skills are garbage...i didn't and don't mean to offend you...i feel your pain...don't get frustrated...zen budda this thing out

get another ls v2...do it again...don't give up on this one...but don't let it stunt your shine

I appreciate it my dude. I'm just bummed, you know? I have these lovely Box Jades just itching to be typed on, a perfect layout to try... And I'm hindered by this for the past two weeks. AND I lifted a couple pads, and my first soldering iron failed halfway through desoldering... It's just been a lot.

I have some ideas to try out, mainly checking continuity between halves and see if it's something I can just jump to fix. At this point, I don't care about beauty, I just want function. I'm just really glad I socketed these Pro Micros and got a spare, just in case it is the PMs after all.

[jimirolln]

i didn't think to ask...is it v1?...either way i found this...i don't know if it will help...but it is a good watch regardless

[WallofYawn]

Nah, it's a V2.

[jimirolln]

you know you have a good pm on the master now...have you tried swapping the slave pm with it to make sure it is good?

what temp do you solder @?

[jimirolln]

i won't presume to know...because for me i would have walked away after toasting that pad...and i don't know about all that jumper biz

but have you considered desoldering the jump and jumping to that other pad to the left?

[WallofYawn]

i won't presume to know...because for me i would have walked away after toasting that pad...and i don't know about all that jumper biz

but have you consider desoldering the jump and jumping to that other pad to the left?

They're both good, each side works independent of the other, they just don't communicate via trrs.


My reasoning for jumping the TRRS that way was essentially, it's a mirror image of the other side. So, the jumped pin should (if my reasoning is correct) make the same connection to that other pad... Make sense? It doesn't matter anyway, as it didn't change anything for better or worse.

I solder at between 325c and 350c, but my iron is a piece of junk, so I have no idea the real temp. 63/37 solder.

[jimirolln]

https://www.amazon.com/gp/product/B074V28ZVS/ref=ox_sc_act_title_5?smid=A300WH98NR1I83&psc=1

https://www.amazon.com/gp/product/B00UVSESSQ/ref=ox_sc_act_title_4?smid=A15QN6QABYC6HS&psc=1

27 bucks...316c

12...not necessary but the physics of rapid temp change with the sponge is no good...same with warming up the iron...start with the lowest setting before cranking it up...expansion rate and what not...the heating element is in the core...better design...but sensitive to physics

[WallofYawn]

Turns out the pin labeled 3 on the slave pro micro was not working. I'm guessing this is the pin that controls communication. Thanks for everyones help.