User manual

Page 20

The board is equipped with

16MHz

crystal oscillator (X4) circuit that

provides external clock waveform

to the microcontroller OSC0 and OSC1

pins. This base frequency is suitable

for further clock multipliers and ideal for

generation of necessary USB clock, which ensures

proper operation of bootloader and your custom USB-

based applications. The board also contains

32.768

kHz crystal oscillator (X5) which provides external clock for

internal RTCC module. Microcontroller ADC requires an accurate

source of reference voltage signal. That is why we provide the external

voltage reference to the microcontroller VREF pin which is 2.048V.

5. Crystal oscillator and 2.048V reference

01 02

Figure 5-1: Crystal oscillator

and 2.048V reference