I am trying to send AT commands from my ESP32 to a Quectel BG95 (modem) using arduino IDE and a UART connection. Because the UART pins on the modem need 1.8V though I have to use a logic level shifter. The hardware design for the modem gives:
My attempt basically looks the same:
Datasheet for logic level shifter
ESP's RXD are connected to Modem's TXD and vice versa. But I am getting some strange voltage measurements that I cannot reconcile. Basically the ESP's TXD is reading 2.733V corresponding pin on modem side (RXD) is reading 1.72V. My ESP's RXD is reading 3.33V corresponding pin on modem side (TXD) is reading 1.72V.
This can't be right, or am I missing something? But even if it is wrong I am not sure what to suspect here. Does anyone have a faint clue what it might be?