ESP32 Forum

Hi,
When I try to program an ESP32-S3 that is in a custom design I made, consisting of 2 ESP32-S3s together, the device manager detects the COM port where the ESP is connected. However, when I go to upload the program using Arduino IDE, a message appears indicating that the port does not exist.
Trying to solve the problem, I saw that the probe I use, ESP-PROG, has the RX LED blinking constantly. When I observed the TX signal from the ESP32, I got the following signal


Then I opened a port using Hercules and managed to connect, and I could see that the ESP32 sends many reboot messages for no apparent reason.


Then I measured the voltage on IO0 of the ESP32 and it had a value of approximately 4V. Additionally, I saw the CHIP_PU signal and it was permanently at 3.2V, which is correct and should not cause a reboot
What could be happening? I have attached some PCB design photos of the small module. Additionally, the two ESP32-S3s are covered by a single protective shield


The strangest thing about all this is that I had previously uploaded blank programs to that ESP32 without any problems.

Then I measured the voltage on IO0 of the ESP32 and it had a value of approximately 4V

If you have 4v on IO0 you have a major problem. It should never be above 3.3v

Since it is a custom-designed board, manufacturing errors are quite possible. IO0 at 4V is abnormal; IO0 is expected to have a logic level of 0V (low) or 3.3V (high).When programming, IO0 should be pulled low to enter bootloader mode. An incorrect pull-up resistor value or pull-up connection on IO0 can create this problem. An accidental short to a higher-voltage rail or interference from another circuit can also cause this anomaly. Check the PCB for any shorts or incorrect routing on IO0. Also check the connection between ESP-PROG and ESP32-S3 (TX, RX, GND). If ESP32-S3 programming is tough, you can get/make a board like ESP32-S3 1.47inch Display Development Board. Its Onboard 1.47inch LCD screen can smoothly run GUI programs such as LVGL. The board is combined with various peripheral interfaces, suitable for the quick development of the HMI and other ESP32-S3. applications.https://www.pcbway.com/blog/27/PCBWay_S ... e88e9.html