Hi all!
I am new to PCB design. I am currently working on a project that interfaces 64x64 sensors with the Arduino. The sensors are connected to two 32:1 multiplexers for each row and column. And the output of these multiplexers goes into some other chip. This new chip communicates with the arduino via i2c protocol. I had already designed the PCB and placed the order. After receiving it, the PCB is not working. Neither the ICSP circuit nor USB-UART are working. Can you spare some time to help me find errors with the PCB board so that I can design it and place an order?
I moved your topic to an appropriate forum category @kapple1736.
In the future, please take some time to pick the forum category that best suits the subject of your topic. There is an "About the _____ category" topic at the top of each category that explains its purpose.
Where is the ground pour?
There seems to be 4 times the same unit on your pcb. Can you test one such unit first? Maybe by sending that part to make a smaller pcb?
You seem to make a huge step at once...
But once put together, it is very hard to trace back errors (as you cannot isolate the problem).
And as said above: we would need an electric circuit as well as an annotated pcb design. How are we supposed to know if a connection is meant to be there or not...
The Pads are not shorted. It is just the image that makes it look like so.
About the Project:
Sensors in 64*64 row-column matrix array are to be interfaced. The output of the rows and columns of this matrix goes into the two 32:1 multiplexers for each row and column. The output of the multiplexers goes into the CDC AD7746 chip. The CDC chip communicates to the atmega328pb chip via i2c protocol. This is the sensing part. Now, the processing part consists of an atemga328pb chip with a USB serial converter ft232rl chip connected via USB c for programming. it also has icsp header for boot loading the program. Besides, the board contains four 32 pin connectors for sensor interfacing.
Your traces are way to close and I don't have the time to troubleshoot this whole mess. One glaring error I do see is a red trace leaving U1 (can't tell exactly what pin, but I'm thinking it's pin 7 (bottom right), which makes direct contact with MOSI and SCK (no wonder your ICSP doesn't work). Others around/through the ICSP connector also look very close.
If you post an image that looks like pads are shorted when they are not how are we supposed to tell the difference between an actual problem and something that just appears to be a problem? Please post an image that is clear enough to actually see what is going on.
The general impression from the picture - it is a very inaccurate routing and too small clearance between tracks, tracks and pads, tracks and vias - even where there is no need for it:
Or on ICSP - why all tracks going out from the pads in vertical directions - actually resting on the adjacent pin?
Did this produced by "Automatic routing" feature of the CAD software? - It is useful at the initial stage, but then you need to correct all such places manually.
The main problem with improper clearances is that you can very easily short-circuit adjacent tracks when soldering. And then it is very difficult to notice. You need to check the entire board for such short circuits by DMM.
You are right, i have generated it from the automatic CAD software. But the final schematic doesn't have this 90 degree routing problem. I have the changes in the final all over the board.
Clearance is something I didn't notice given the fact board, so number of routings. More than 150.
That is, the picture shown in #18 has nothing to do with reality? Why did you post it ?
This is the second time you’ve posting fake diagrams and asked to tell you what’s wrong with it! What kind of help do you expect in this case? Or are you just trolling forum members?
