ESP8266: Able to flash but no program execution

Question

I designed a PCB based on the ESP8266EX dotn here is the schematic:

To flash the board I use the module: https://joy-it.net/de/products/SBC-ESP8266-PROG I am able to flash the board with Arduino IDE with a simple code:

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  Serial.println("OK");
}

void loop() {
  // put your main code here, to run repeatedly:
  Serial.println("OK");
  delay(1000);
}

But when I open the serial monitor, nothing happens.

All the pins of the 8-pin connector are connected respectively to the Joy-it module.

Flash configuration :

• Card Type: Generic ESP8266 Module"
• Upload Speed: "57600
• CPU Frequency: "160 MHz
• Crystal Frequency: "40 MHz
• Flash Size: "4MB (FS:3MB OTA:~512KB)"
• Flash Mode: "DIO"
• Flash Frequency

I've tried different flash configurations without success.

I wonder if it's a connection problem between CHIP_EN and RST pin.

Flash datasheets: https://datasheet.lcsc.com/lcsc/2201121400_HTCSEMI-HT25WD40ARZ_C2928800.pdf

ESP8266EX datasheet: https://www.espressif.com/sites/default/files/documentation/0a-esp8266ex_datasheet_en.pdf

Answer 1

Since you can upload the code, many things are going right. I can suggest the following:

1. Check the GPIO0 pin if it becomes high after you upload the code. If not, try to pull it up using an external 10K resistor. Verify at the ESP pin if the pin is actually going HIGH or not.

2. I am wondering if the programmer is interfering somehow. Try disconnecting the programmer once you are done. Use a regular USB-UART module and make GND, TX and RX connections to the ESP. See if that works. Probably using a simpler code (led blink) as suggested by starcat in the comments can help you debug it easily.

3. Check if the crystal is working fine. Whether the part number is correct, soldering is correct, capacitors in the crystal circuit are correct etc.

Answer 2

Flashing the card in DOUT mode solved the problem