user72411: I'm making my own Arduino Mega board with ATmega2560-16AU and CH340G. Jump to the end of the post to find the real question.
I have already ordered a PCB before and it didn't work when I soldered everything in place. I have already asked why that board didn't work on another post here: Programming custom Arduino Mega with Arduino Uno
But I was not satisfied with the answers and started suspecting whether or not the capacitor values were right on my board.
I'm trying to make my own version of RobotDyn's Arduino Mega 2560 Pro so I tried taking the already programmed ch340g and soldering it on my own board and still failed. When I put a previously not programmed ch340g on the RobotDyn board and programmed it using Arduino UNO (Arduino as ISP) the board would work.
So now I ordered a new PCB but haven't ordered any of the passive components yet.
If any of you could tell me where I could find the values from the schematic below I would really appreciate that.
https://robotdyn.com/pub/media/0G-00005641==MEGA-PRO-CH340GATmega2560/DOCS/Schematic==0G-00005641==MEGA-PRO-CH340GATmega2560.pdf

user50339: The values can be easy found for generic CH340g and ATmega2560 implementations:
C1,C2 = 100nF, C3,C4 = 22pf but depends on the crystal you use, all others excepting C12 are decoupling capacitors.
C12 has no sense where it's placed, it seems that the schematic is a bad combination of schematics, this capacitor should reset the board at power on but it breaks the reset pulse from CH340g so you cannot program the board without pressing manually the reset pushbutton. Don't place C12 at all.
Also place a short instead of R5 and R6 that are not in the CH340g manual (there is a special mention to connect the pins straight to USB bus), remove R8, is not needed for the same reason, R3 makes no sense, don't place-it.
R2,R4 = 1K, R7,R9 = 10K, R10,R11,R12,R13 = 1K, R14 = 10K , R15 = 1M.
Y1 = 12Mhz, Y2 = 16Mhz
A 22 ohm resistor is missing in your schematic between Y2 XTAL1 and ATMEGA XTAL2 but I don't think it's important.
I hope I didn't missed something
The bare minimum is to remove c12 and maybe R3 and check the values you used for R2, R4 against the above values.
If something would be wrong with CH340g the USB connection would fail but I see no mention about that in your post.

72411: <p>I'm making my own Arduino Mega board with ATmega2560-16AU and CH340G. Jump to the end of the post to find the real question.</p>
<p>I have already ordered a PCB before and it didn't work when I soldered everything in place. I have already asked why that board didn't work on another post here: <a href="https://arduino.stackexchange.com/questions/81361/programming-custom-arduino-mega-with-arduino-uno">Programming custom Arduino Mega with Arduino Uno</a></p>
<p>But I was not satisfied with the answers and started suspecting whether or not the capacitor values were right on my board.</p>
<p>I'm trying to make my own version of RobotDyn's Arduino Mega 2560 Pro so I tried taking the already programmed ch340g and soldering it on my own board and still failed. When I put a previously not programmed ch340g on the RobotDyn board and programmed it using Arduino UNO (Arduino as ISP) the board would work.</p>
<p>So now I ordered a new PCB but haven't ordered any of the passive components yet.</p>
<p><strong>If any of you could tell me where I could find the values from the schematic below I would really appreciate that.</strong></p>
<p><a href="https://robotdyn.com/pub/media/0G-00005641==MEGA-PRO-CH340GATmega2560/DOCS/Schematic==0G-00005641==MEGA-PRO-CH340GATmega2560.pdf" rel="nofollow noreferrer">https://robotdyn.com/pub/media/0G-00005641==MEGA-PRO-CH340GATmega2560/DOCS/Schematic==0G-00005641==MEGA-PRO-CH340GATmega2560.pdf</a></p>
 50339: <p>The values can be easy found for generic CH340g and ATmega2560 implementations:</p>
<p>C1,C2 = 100nF, C3,C4 = 22pf but depends on the crystal you use, all others excepting C12 are decoupling capacitors.</p>
<p>C12 has no sense where it's placed, it seems that the schematic is a bad combination of schematics, this capacitor should reset the board at power on but it breaks the reset pulse from CH340g so you cannot program the board without pressing manually the reset pushbutton. Don't place C12 at all.</p>
<p>Also place a short instead of R5 and R6 that are not in the CH340g manual (there is a special mention to connect the pins straight to USB bus), remove R8, is not needed for the same reason, R3 makes no sense, don't place-it.</p>
<p>R2,R4 = 1K, R7,R9 = 10K, R10,R11,R12,R13 = 1K, R14 = 10K , R15 = 1M.</p>
<p>Y1 = 12Mhz, Y2 = 16Mhz</p>
<p>A 22 ohm resistor is missing in your schematic between Y2 XTAL1 and ATMEGA XTAL2 but I don't think it's important.</p>
<p>I hope I didn't missed something</p>
<p>The bare minimum is to remove c12 and maybe R3 and check the values you used for R2, R4 against the above values.</p>
<p>If something would be wrong with CH340g the USB connection would fail but I see no mention about that in your post.</p>
