I'm currently trying to decide if I need an external xtal for my design that's using a STM32F103xF mcu.
The accurate timing requirements I can see being necessary are for programming the device over USB and possibly with JTAG.
I've seen that USB 2.0 is specced to requiring a frequency deviation of no more than +- 0.25% which is quite outside the range of the F103 HSI, but I can't find if there's a set deviation requirement for JTAG.
The mcu has a deviation of -2 to +2.5% off the HSI RC Osc , does anyone know if this will suffice to flash over JTAG? If I can avoid putting an external XTAL on my board it would save a lot of headaches as I'm extremely space constrained but will do it if necessary to flash and debug the mcu.