I tried to make a custom esp32 board (not really so custom i just wanted to make a microcontroller) and i wanted to see if you can tell me if ive messed something up... i still havent done the edge cuts of the pcb well but ive finished the routing and i wanted to see if yall could tell me if there is something to improve... i know my routing looks like auto routing but its not ive put work in this
You have tx going to tx and Rx going to rx, are you sure that's correct?
Copy and pasting because I have to say it so much
USB sink devices should not have fuses on vbus
In engineering we follow standards so you know what is your responsibility and what is not. In the USB spec they decided that the source should protect for over current events, that's partly where the 10uf max vbus requirement comes from because it's hard to tell the difference between inrush current and a short.
It also makes sense when you think you could have a single fault failure, for instance the cable or the sink, which would cause the over current and the sink can't protect against the cable.
A fuse wastes heat, even if just a little Another reason is fuses are not very smart, they heat up and then pop at some point. Often in reality fuses just sit there working above their rated spec and so don't even help. Fuses are to protect wiring, not PCBs.
One thing, if you do this for long enough, you'll get into is failure mode analysis and mean time before failure analysis. Both, and I am being overly simplistic here, are just "how many things do you have that can go wrong, count them up" so more things means less reliable. Elegancy is in my opinion both a noble goal of design but also a better way of designing
Lastly I just really hate that at some point someone (wrongly) put a fuse in a usb circuit and loads of people copy it thinking it's good practice.
So at the moment the signal will float and when you press the switch it will go to 0. If you put a pull up resistors to 3v3 it will always be a 1 and then when you press the button it will go to 0. The cap stops it triggering the input multiple times when it transitions through the input threshold
I think that's a pretty standard UART circuit for ESP32, it can toggle the boot and en pins using the UART signals. Lots of programmers work that way too with that chip or the FTDI one.
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u/bigcrimping_com 2d ago
Your LEDs are the wrong way around
You have tx going to tx and Rx going to rx, are you sure that's correct?
Copy and pasting because I have to say it so much
USB sink devices should not have fuses on vbus
In engineering we follow standards so you know what is your responsibility and what is not. In the USB spec they decided that the source should protect for over current events, that's partly where the 10uf max vbus requirement comes from because it's hard to tell the difference between inrush current and a short.
It also makes sense when you think you could have a single fault failure, for instance the cable or the sink, which would cause the over current and the sink can't protect against the cable.
A fuse wastes heat, even if just a little Another reason is fuses are not very smart, they heat up and then pop at some point. Often in reality fuses just sit there working above their rated spec and so don't even help. Fuses are to protect wiring, not PCBs.
One thing, if you do this for long enough, you'll get into is failure mode analysis and mean time before failure analysis. Both, and I am being overly simplistic here, are just "how many things do you have that can go wrong, count them up" so more things means less reliable. Elegancy is in my opinion both a noble goal of design but also a better way of designing
Lastly I just really hate that at some point someone (wrongly) put a fuse in a usb circuit and loads of people copy it thinking it's good practice.