Hi,
to be honest, I´m quite confused.
So much schematics, some are similar, some are totally different.
I never know which one is from you and which one is from other sources (internet, datasheet).
Then there are comments in the schematics ... Some are from you, some are not from you, some just don´t fit to the schematic.
I don´t know how to treat them.
My recommendation: post ONE schematic, focus on ONE topic. Ask clear questions (max 3, as text, not in the schematic) referring to the schematic.
(But keep names consistent. If VCC on one schematic is 5V, then don´t use a node with name VCC but for 3.3V.
Try to keep part names unique. If there is a resistor "R1" on one schematic, don´t use a resistor "R1" on a different schematic.
This helps to prevent from misunderstandings, especially on public discussions.
I personally like naming this way: Resistors on schematic page 1 are R100 ... R1xx, on page 2: R200...R2xx)
*****
Example: let´s focus on the power supply.
Let´s say you have two batteries, 12V each, a bunch of cables, and a DVM showing DC values.
Q: how would you wire it all, so that the DVM shows +24V?
If you can solve this. --> just do the same with the output(s) of the DCDC converter. It´s basically the same. (just the values are different)
***
Mind:
* the DVM has two inputs. Usally one is black, the other is red. In most cases the black one is what in your circuit is called "GND" (especially when no other reference is mentioned).
* A DVM measures the voltage of the red node with respect to the black node.
* When you see: "VCC = 3.3V" .. there is no reference mentioned, thus the reference is GND. In detail it means: "The voltage of VCC with respect to GND is 3.3V"
* But when you see: "V_GS = 4V" (like for a MOSFET), then "S" is the reference. In detail it means: "The voltage of G (gate) with respect to S (source) is 4V"
Klaus