Prototype circuit design ESP-WROOM-32

[jerry.hubbell]

I am integrating the ESP-WROOM-32 into an existing controller design (commercial) that previously used the RN-131 WiFly module. I have attached the schematic for the ESP-WROOM-32. I have connected a USB to Serial adapter (FTDI) that has been verified and is working fine. I power up the prototype board and using Putty, connect to the serial port (COM8) and can see traffic going between the host and the ESP-WROOM-32 module. The issue I am having is that the communications are garbled. I expect to see normal human readable ASCII but I get what is shown in the attached picture. The communications parameters are: 115200, N81 No handshaking.

The ESP-WROOM-32 module SSID shows up, and I can connect to it fine on the wireless side. It connects and assigns an IP Address of 192.168.4.xx The ESP-WROOM-32 module has the IP Address of 192.168.4.1. Is there a way to TELNET into the module over the wireless interface? I tried the standard TELNET port. What ports are available? The module was purchased and assembled on the prototype board by the assembly house, Laritech, Inc. How are these modules delivered by Espressif? What is the default configuration?

My goal is to set this module up as a Serial to WiFi bridge. It would be great if it worked that way out of the box.

Any information or help in resolving this communications issue would be greatly appreciated

Jerry Hubbell
Explore Scientific, LLC.

[jerry.hubbell]

I am curious if anyone sees anything obvious with my circuit design or has an opinion about what would cause an issue resulting in the garbled traffic on the port.

Thanks

[jerry.hubbell]

I have attached the UTF-8 encoded serial stream that I get out of the module when booting. Perhaps that will give a clue as to what is going on.

[jerry.hubbell]

I figured out that the circuit did not have the required TX and RX inverter gate, that is why the data looked garbled. I researched it a bit and found that the FTDI FT232R chip I was using has a way to invert the signals on TX and RX so I did that and now the data look great. I hope this helps others in the future.

[ESP_Sprite]

Erm... you're not using an USB to RS232 converter, are you? Because these output signals at +/-12V and feeding these into the ESP32 can/will damage it. Use an USB to TTL-level (well, 3.3V-level) serial instead; you shouldn't have to need to invert any signals with these.

[jerry.hubbell]

No, the adapter I am using is 3.3 v to the ESP-WROOM-32. The problem was that the signals were inverted out of the FTDI adapter, so I inverted them in the FT-232R EEPROM setup, it works fine now.

[ESP_Sprite]

Okay, cool inverting the signals is also what happens in a 'real' RS232 converter, but that also makes the signals into +12/-12V, which worried me for a bit.