iuls In order to add the 4-pin female socket header to the line output to the Bela cape (J9) [step 24 on the CBG], do I have to take off the cape.
yes
I know the question sound stupid but the both plates are very strongly connected together. I tried to pull a little bit but there is no way to take them apart.
With a flathead screwdriver and a bit of care, you'll get there. See this video
be very soft in your movements, do not bend pins.
Maybe can I put the 4-pin female socket on Bela cape without soldering it ?
No.
iuls Once I will attach Bela with Pepper, do you think I could take apart easily in the way to use Bela without Pepper ?
yes I think so. You can use a similar technique to the one in the video above.
iuls What’s your thoughts about this idea, do you think I will have interference, impedance, noise problems ?
It should work, because there are no high speed digital signals going between the two. Noise performance may be slightly degraded, but I am not sure it's going to be perceivable. The main issue is that you'll then need to somehow secure the Bela to the case so that it doesn't rattle around. You surely don't want it to touch other modules as it could get damaged mechanically and/or electrically.
iuls if I don’t put any jumper on the pins the Pepper will be in the « default configuration »
no. Without jumpers neither analog nor digital inputs will work for that input channel.
iuls What’s the purpose of the 2 « analog » pins located on the side of the A/D 4 pins ?
You need two jumpers per each channel . If they are placed in on the "ANALOG" pins (this is the default behaviour, as shown in the last picture of the build guide), the input jack will work as an analog input. If they are placed on the "DIGITAL" pins, the input jack will work as a digital input.
iuls some differences between both and I wanted to check if I didn’t make wrong choices :
this is for @bela_robert.