Can I use MCU's internal oscillator when communicating with GPS and cellular modules?

[maryam magdy]

Can I use MCU's internal oscillator when communicating with GPS and cellular modules? I want to avoid connecting external crystals for the MCU since they generate noise, extra components, extra costs, and on top of that require PCB design constrains and cautions. My MCU is stm32 L432kc

[Tesla DeLorean]

Yes, UART comms have a pretty wide error margin for clocks.

USB/CAN/ETHERNET significantly less so

[S.Ma]

Check the internal oscillator min/max frequency based on tolerance and junction temperature range. Check if this is ok depending on the chosen baudrate. When baudrate increases, tolerances on the reference clock gets tighter. (also check the other end device tolerances in timings)