ESP32 Forum

I have been working on a design using an esp32-wroom-ue-n8. Having 2 issues and I think they are both related.

In order to upload a sketch in Arudino I have to jumper io0 to gnd. This isn't a huge deal cause I could just add a tact switch but would like to avoid that.

The bigger issue though is that I am not getting any serial output when using serial programs such as Putty or Teraterm but I get serial output when using Serial Monitor within Arduino. I havent seen this happen before. Thinking it may be code I uploaded a simple Wire Scan sketch to rule it out. Same results.

I think the 2 are related. The schematic is based on the Wemos D1 mini esp32.

What do I have wrong on the board that would cause both of these issues?

Screenshot from within Arudino & schematic attached.

There seems to be an issue with the RTS/DTR handling.
If the pin names of the transistor IC are correct, there is an error in the wiring: RTS should connect to the base of one NPN ("A") and the emitter of the other NPN ("B"), and vice versa for DTR (base of "B" and emitter of "A").
If you then also connect "COLLECTOR_2" to IO0, you get software control of EN and IO0 and should be able to reset, flash and monitor the chip w/o manually pulling EN or IO0 high/low. See e.g. https://electronics.stackexchange.com/q ... rd-dtr-rts

Thank you for the reply.

Not sure why the wiring though would explain why Arduino Serial Monitor is able to see output but nothing else can. The above would explain why I have to jumper io0 to ground, I get that. But why cant anything other then Arduino serial monitor see the serial data?

I have loaded the example Wire Scan sketch
connected usb cable to device
Open Putty(as an example)
Set to Com4(com port for device)
Nothing is displayed

Just curious; why would you be using 9600 baud with an ESP32?

Also, I have this exact same board. It works flawlessly. How old is your board? (i.e. when did you purchase it?)

The chip is brand new, jut came off the assembly last week. Using 9600 cause that is all that is needed.

@Microcenter - I am not manually pulling anything high or low when looking at Serial Monitor. Understand why I have to manually jumper io0 now to get it to load the sketch, but not understand why I can't monitor the output once the sketch is loaded using anything but Arduino Serial Monitor.

Does this schematic look correct? I really messed up the pins on the MBT3904

Anyone have any thoughts?

1) No current limiting resistors on the bases of the NPNs
2) Swapped RTS/DTR signals.