ESP32 PPP disconnection re-connection issue

[ESP_Sprite]

That resistor is there because of EMC reasons... if during your EMC testing you find out that there's emissions from your UART1 TX pin, you could try also putting a 470 ohm resistor there, but from what I know, it's only an issue on UART0. Regardless, having or not having the resistor shouldn't affect anything else.

[AdiXPS]

That resistor is there because of EMC reasons... if during your EMC testing you find out that there's emissions from your UART1 TX pin, you could try also putting a 470 ohm resistor there, but from what I know, it's only an issue on UART0. Regardless, having or not having the resistor shouldn't affect anything else.

Thanks so much for information. I've scoped the RX/TX and I notice that there are voltage spikes while RX/TX in UART1. when I add series resistor its much more smoother.. I've came over this issue https://github.com/espressif/arduino-esp32/issues/2198.

Moreover, may I know the value of internal pullup resistor in esp?

Would like to get your opinion on above, thanks!