Just received 4 modules ESP_WROOM_02. I already have 2 of them with issues. I followed directions from the SDK getting started guide and was abale to play with them using Linux + TFDI USB-serial adapter. IO0 is left floating when used in run flash mode, and connected to gnd for UART download mode. IO15 is grounded. IO2 is set to VDD.
They are running an AT firmware, and I used AT commands to play with both of them (associate, ping remote server, create TCP connection and POST / GET data over HTTP).
So the HW setup is correct in line with the Gettint Started guide and was able to send / receive HTTP data.
Both actually worked until some time. Here are the symptoms for each of them:
- The first module keep sending a 0110 sequence on the UART_TXD line @ 115200 bps each time I press a key on the terminal (which is correctly sent out on the UART_RXD line, confirmed on the scope.). I tried to reflash binaries from the SDK (v2 and v1_5) this works fine, but I still get the same error (0110 seuqnece on the UART_TXD line) when i switch back to run flash mode. Yet they are kind of working as the module is in Soft AP mode and I can see it. I just can't communicate with it over UART.
- The second module stopped working. It cannot even enumerate in UART download mode, so I can't update the Firmware.
Any idea what might go wrong here ? Are the modules dead ? What could be the next steps to rootcause and fix the issues ?
Thanks