You could use PetitModem, don't ask me how it works though, as I have never used it.
How to put 3DS photos into SmileBASIC???
Spoiler
There's already a petit modem thread, (https://smilebasicsource.com/forum?ftid=7&page=4) check there for (hopefully) some answers.
I had to figure out photo transfer for my Continuance game. I saved the image as a PPM (GIMP supports this format) then transferred it over audio cables with PetitModem. On the other end I wrote software to decode it and draw it to the screen (I picked PPM because it's an incredibly simple format). After that I saved the image using GSAVE so I could later load it very fast using GLOAD.
In my experience PetitModem doesn't work at all through an actual microphone and speakers. You absolutely need audio cables, especially for an image as it will take quite a long time to transfer an image. Audio cables will also let you transfer audio to your game as well (that voice sample in my Ringman game was transferred over audio cables), so I'd highly recommend them.
I bought this splitter recommended by PetitProfessor3D and two of these Amazon Basics auxiliary cables. Seemed to work for me.
Although strangely the 3DS will only sometimes recognize sound through the microphone port so I'd constantly have to unplug it and restart the software until it finally recognized it but when it did it transferred without a hitch (albeit very slowly).
That won't work since the mic and speaker signals need to be swapped. Otherwise the 3DS speaker output connects with the laptop speaker output, rather than the mic input like it should.What if you just one headphone port on your laptop(a headphone and microphone port in one port) ???You might have some luck using a single TRRS cable between the 3DS and computer, since they both have TRRS jacks. I tried that and didn't have much luck though for some reason.
Actually it did work.That won't work since the mic and speaker signals need to be swapped. Otherwise the 3DS speaker output connects with the laptop speaker output, rather than the mic input like it should.What if you just one headphone port on your laptop(a headphone and microphone port in one port) ???You might have some luck using a single TRRS cable between the 3DS and computer, since they both have TRRS jacks. I tried that and didn't have much luck though for some reason.
h-hOW?! I need to try this with all of my cables nowActually it did work.That won't work since the mic and speaker signals need to be swapped. Otherwise the 3DS speaker output connects with the laptop speaker output, rather than the mic input like it should.What if you just one headphone port on your laptop(a headphone and microphone port in one port) ???You might have some luck using a single TRRS cable between the 3DS and computer, since they both have TRRS jacks. I tried that and didn't have much luck though for some reason.
Send it with simplex in a quiet environment.h-hOW?! I need to try this with all of my cables nowActually it did work.That won't work since the mic and speaker signals need to be swapped. Otherwise the 3DS speaker output connects with the laptop speaker output, rather than the mic input like it should.What if you just one headphone port on your laptop(a headphone and microphone port in one port) ???You might have some luck using a single TRRS cable between the 3DS and computer, since they both have TRRS jacks. I tried that and didn't have much luck though for some reason.