I spent most of the weekend trying to figure out why the circuit I made to upload firmware to an ESP32 (datasheet doesn't work. The reference circuit below was taken from EspressIf and I tried to recreate this on my own. This is the manufacturer of the ESP32 chip so it should work. If anyone has a clue what it could be, that would be most helpful because I am at a loss at this moment.
I checked for shorts and proper connections on most of the key components: bridge IC(datasheet, micro-USB, ESD diodes. But it is not working. I do want to mention that the RXD and TXD lines are each going through a multiplexer that is acting like a switch which is closed to the firmware upload serial connection when Vbus is connected. I can go into detail, but I no longer suspect this is the issue.
Some observations and general info:
- 3.3V continuous net which receives power from Vbus is reading 3.3V
- Vbus net is reading 5V
- DP is reading 3V
- DN is reading 0V
- Soldering was done with reflow oven and stencil
- The error I am seeing with the circuit is when I plug in the device windows says something like "does not recognize device and it may have malfunctioned".
close-up of micro-usb. I have attached a stripped micro-usb and verified no continuity between all adjacent pads. I have also verified that there is continuity to each respective diode at the beginning of the circuit. So for example Vbus and D304s continuity has been verified.