Note that U4, a 10 MHz MEMS oscillator, is also very close to the microcontroller’s clock input pin. It’s always a good idea to minimize the length of traces carrying high-frequency digital signals. First of all, there are noise benefits: a shorter, more direct trace reduces the amount of noise that would otherwise be coupled into adjacent traces, and a shorter trace also reduces electromagnetic interference (EMI) because it is less effective as an antenna. The second issue is related to transmission-line effects. Minimizing trace length is a simple way to avoid problems related to signal reflections. However, reflection is not a significant concern at frequencies in the 10 MHz range, unless you are dealing with long interconnections or a very large PCB.
Reset pin may be used to generate a system reset of the IC. And while a reset may also be externally generated by issuing a command (referred to as a soft reset), to achieve a full reset it is recommended to use the nReset pin (or of course you can also cycle power). On the other hand, if this pin is not to be used then it is recommended that it is either left floating or tied to VDD via a series resistor of value ≥2 kΩ.
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