ESP32 UART-USB Brige How to use

[stefan.erni]

Hi Martin

Very good, that's something.

Unfortunately, no success yet.
I always get a message saying that the baud rate of Com5 is not supported.
And then com5 is blocked.
Can you tell me which S3 board you have and post your program?

[mnfisher]

I used https://www.amazon.co.uk/diymore-ESP32- ... r=8-5&th=1

(there must be a better way to get a link out of amazon?)

I find I can 'lock' the board - when I need to press and hold 'boot' and then press and release reset to get Windows to recognise it.

I just do a loop with :

Code: Select all

 printf("Hello World\r\n"); 

delay(1s)

If I add a Flowcode UART - channel 1 will open (BUT writing to it doesn't send anything- and the pins can't be selected) - channel 2 seems to lock the board (I tried 19 and 20 (message as above)

When it works - I get the usual esp32 'preamble' - output first then 'Hello.... repeated. Pressing 'reset' closes the COM port - but I can reopen to get

ESP-ROM:esp32s3-20210327
Hello world
Hello world
....

I also toggle a pin (and have a logic analyser attached) - for when I was first looking for 'life'

COM port setting - if I use PuTTY - I use 115200 baud - if I use idf.py -pCOM5 -b 921600 flash monitor - it probably uses 115200 for the monitor (upload is at 921600)?

Occasionally I need to hit the reset button when starting monitoring to get past the 'waiting for download' message.

Currently using 5.4.1 - although I might revert to 5.5 and see if there any differences?

Martin

[stefan.erni]

Hi Martin


I found more infos, But I can't find the TinyUSB setting in sdconfig.
Actually, this should already be available in sdconfig.

Option 2: With TinyUSB (full USB functionality)
If you need data transfer like a real USB bridge, you must enable the TinyUSB stack.
To do this:

Add the component:
idf.py add-dependency esp_tinyusb~2.0.0

Afterwards, the following options will appear in menuconfig:
Component config → TinyUSB Stack
[*] Enable TinyUSB
[*] Enable CDC class

This sets:
CONFIG_TINYUSB_ENABLED=y
CONFIG_TINYUSB_CDC_ENABLED=y
CONFIG_USB_DEVICE_ENABLED=y

Initialize in the code:
C#include “tinyusb.h”tinyusb_driver_install(&tusb_cfg);Show more lines

This allows you to use your own USB CDC endpoints and send data as you would with a virtual COM port. [docs.espressif.com], [github.com]

[stefan.erni]

I downloaded the Flowcode_Compiler_ESP_5.3a.msi and and installed.
FC11 works right away.

However, the section for USB does not appear in the menu.

2025-11-19_11-13-04.PNG (55.12 KiB) Viewed 254 times

[mnfisher]

Hi Stefan,

i've only had time for a brief play (using 5.5) - I managed to compile a demo successfully - but the program threw errors (TinyUSB task cannot have size 0 or similar)

But will experiment some more....

Martin

[stefan.erni]

Hi Martin

that's quite something

I had to enter commands via the console, then I could start the menu and TinyUSB appeared in the menu for the first time.
(I have no idea how to do that in FC11.)

This TinyUSB is for ESP32-S3 and not for all Classic ESP32
All ESP32 chips can send UART data, but:
Classic ESP32 only via external USB-UART chip.
ESP32-S3 additionally directly via USB-CDC (TinyUSB)

Probably a TinyUSB task needs to be created or used?

But then it should simply be possible to send data to the PC via uart0 to pin

Select the UART component and set it to UART0.
TX = GPIO43, RX = GPIO44 (default for ESP32-S3).
Flowcode sends data via UART0 → the chip's USB-CDC forwards it to the PC.

for the console:

Code: Select all

idf.py create-project c:\\usb_cdc_demo
cd c:\\usb_cdc_demo
idf.py add-dependency esp_tinyusb~2.0.0
idf.py menuconfig

Perhaps this can be done via defaults?

Code: Select all

sdkconfig.defaults

CONFIG_TINYUSB_ENABLED=y
CONFIG_USB_DEVICE_ENABLED=y
CONFIG_TINYUSB_CDC_ENABLED=y
CONFIG_TINYUSB_CDC_CHANNEL_COUNT=1
CONFIG_TINYUSB_TASK_STACK_SIZE=4096
CONFIG_TINYUSB_TASK_PRIORITY=5

2025-11-20_09-46-22.PNG (64.76 KiB) Viewed 216 times

2025-11-20_09-47-13.PNG (38.11 KiB) Viewed 216 times

2025-11-20_09-48-12.PNG (28.8 KiB) Viewed 216 times

[stefan.erni]

Hi Martin

Do you have any idea how I can set TINYUSB_ENABLED=y and the other settings
in the menu so that it works with Flowcode?

[mnfisher]

Hi Stefan,

Not had much chance to play this week - I'll try and have another bash over the weekend....

Martin