How to use : Flashing the firmware in the ESP32 development board

[giufigi66]

Hello,
could you please explain better step by step the paragraph in object?
I hane installed Visual Studio Code and PlatforIO, but at this step I don't know exactly how to compile the SW.

Thanks in advance

[vincentmakes]

Indeed:

1.The first step once you have plugged the device on the usb port of your computer is to identify its location.

For instance on macOS, type

ls /dev/cu then hit tab (or ls /dev/* to display everything)

It should return something like this /dev/cu.usbmodem1101

Use this value in platformio.ini file.

2.Adjust the secrets.h file with the right settings (client/server mode and other paramters listed

3.Then still in the terminal of VS Code, type

pio run -t clean
pio run -e esp32s3
pio run -t upload -e esp32s3
pio device monitor -b 115200

Note that the esp32s3 matches the value of the environment in platformio.ini file as well

[giufigi66]

Thank you for your prompt answer.
Sorry:

1. When you say "type" do you mean using the terminal of VS Code? Or what else to identify the esp32s3?
   I have a Windows PC, so which is the command in this case?

2. secrets.h already adjusted

[vincentmakes]

Yes, “type” means in the integrated terminal inside VS Code (menu Terminal → New Terminal, it opens a PowerShell prompt at the bottom). The macOS ls /dev/cu... command is just how you find the port on a Mac; on Windows it works differently.
The easy way (no need to find the port manually):
PlatformIO can usually auto-detect the board, so you can skip editing the port entirely. In platformio.ini, just comment out (or delete) these two lines:

;upload_port = /dev/cu.usbmodem1101
;monitor_port = /dev/cu.usbmodem1101

Then use the PlatformIO toolbar at the bottom of VS Code: ✓ = Build, → (arrow) = Upload, 🔌 (plug) = Serial Monitor. That avoids the terminal completely.
If you prefer to set the port explicitly / it isn’t auto-detected:
1. Plug the board in, then in the VS Code terminal run:

pio device list

1. It will show something like COM5 (Windows names ports COM3, COM4, COM5…). You can also check Device Manager → Ports (COM & LPT) — the board appears as e.g. “USB Serial Device (COMx)”.
2. Put that value in platformio.ini:

upload_port = COM5
monitor_port = COM5

2. (replace 5 with your actual number)
   3. Then run the same commands as before in the terminal:

pio run -t clean
pio run -e esp32s3
pio run -t upload -e esp32s3
pio device monitor -b 115200

If no COM port shows up at all: the Waveshare ESP32-S3 uses native USB, so it should appear on its own. If it doesn’t, try a different USB-C cable (some are power-only), or put the board in bootloader mode by holding BOOT, tapping RESET, then releasing BOOT, and check again.

[giufigi66]

Thank you Vincent, I tried to use the terminal to see if everything goes right.
The ESP32 is connected to COM4.

It seems I have some lack of parts on my PlatformIO.
Here the logs reported after the "pio run -e esp32s3" command:

[vincentmakes]

your setup is working - that error seems to be due to the Windows 260-character path limit. LVGL's display drivers use very long nested include paths, and when the project folder is deep (e.g. inside Documents...\Downloads...), Windows can't resolve them and reports lv_conf_internal.h: No such file or directory. That's why it builds on Mac but not Windows.

Fix — two steps:

1. Move the project to a short path near the drive root, for example:

C:\dev\ComfoSense-Touch
(avoid Documents, Downloads, OneDrive-synced folders, and long names).

2. Enable long-path support in Windows. Open PowerShell as Administrator and run:

New-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Control\FileSystem" -Name "LongPathsEnabled" -Value 1 -PropertyType DWORD -Force
git config --global core.longpaths true
Then reboot.

After moving the folder, delete the old .pio folder (it caches the old paths) and rebuild from the new location:

pio run -t clean
pio run -e esp32s3
pio run -t upload -e esp32s3
pio device monitor -b 115200
Since the board is on COM4, set (or leave auto-detected) in platformio.ini:

upload_port = COM4
monitor_port = COM4
Let me know if it gets past the LVGL drivers after that.

[giufigi66]

Hi Vincent,
sorry to distub you again.
Now the compiling phase is OK, but the upload fails.
Which driver do I need?

[vincentmakes]

The “Write timeout” means esptool reached the board but the chip didn’t drop into download/bootloader mode to accept the firmware. The “drivers” line in that message is just a generic esptool hint.
Try these in order:

1. Close the Serial Monitor first. If a pio device monitor or any other terminal still has COM4 open, the upload can’t write to the port and times out. Close it (or close the extra terminal), then upload again.

2. Put the board into download mode manually :
   • Hold the BOOT button down
   • Tap (press + release) the RESET button
   • Release BOOT
   • Then run the upload again (pio run -t upload -e esp32s3) — it should connect immediately.

Also: use a data-capable USB-C cable (some are charge-only) plugged directly into the PC, not through a hub. You don’t need any extra driver : since the board already shows as COM4, Windows has what it needs

You can also try to set the speed to 115200 in platformio.ini

[giufigi66]

1. Where is the Serial Monitor to be closed?
2. I tried this sequence, but without point 1 and no news

The cable is good

I have tied also:
upload_speed = 115200
but no news

[vincentmakes]

I meant just make sure you don't have another terminal open which is using COM4

Which device are you uploading the firmware to ?

[giufigi66]

Waveshare ESP32-S3-RS485-CAN

[vincentmakes]

1.	Open Device Manager → Ports (COM & LPT) and keep it visible.

2.	Hold BOOT, tap RESET, release BOOT. Watch the list — does a new/different COMx appear (e.g. COM5), or does COM4 disappear/reappear with a new number?

[giufigi66]

Bingo!
My fault ... it was COM3.
Now everything good till last command (pio device monitor -b 115200) that I understand is a test to connect MQTT brocker, but:

[giufigi66]

Here my configuration in secrets.h:
#// ============================================================================
// MQTT Configuration
// ============================================================================

// set to false to disable MQTT altogether. MQTT is used for integration with
// home automation system such as Home Assistant
#define MQTT_ENABLED true

#define MQTT_HOST "core-mosquitto"
#define MQTT_PORT 1883
#define MQTT_USER "Mqttuser"
#define MQTT_PASS "MyPassword" --> (of course the right one)
#define MQTT_PREFIX "comfoair"

#define REMOTE_CLIENT_MODE false

[vincentmakes]

Try to put the full hostname of the mqtt broker or its IP

Hostname could be core-mosquito.local, it depends on how you set it up. IP will work for sure

[giufigi66]

As hostname I have:

As IP do you mean this will work (put in " "):
"192.168.178.126:8123"