The WCO is a highly accurate 32.768 kHz clock source capable of operating in all power modes. More...
Modules | |
Functions | |
The WCO is a highly accurate 32.768 kHz clock source capable of operating in all power modes.
The WCO can be used as a source for the WDC (Watchdog Counters).
The WCO requires the configuration of the dedicated WCO pins (wco_in, wco_out). These must be configured as Analog Hi-Z drive modes and the HSIOM selection set to GPIO.
The WCO can also be used in bypass mode, where an external square wave is brought in directly through the wco_out pin. Even though driving wco_in pin would work, better performance will be achieved using wco_out pin since we can bypass the feedback resistor which causes an RC delay and duty cycle variation. The wco_in pin should be floating, however, if floating is not desirable, then a minimum input impedance of 500kOhm to ground is required on the wco_in pin. An external clock source should toggles from 0V to a minimum of 1.0V and 0V to a maximum of 1.6V with duty cycle 20% to 80%. For stable WCO operation using an external clock source, the VDDA/VDDD external supply should be in the range of 1.65V to 5V.
Start up sequence of the WCO in bypass mode: