Datasheet

Chapter3 Functional Description 25
3.21 Real Time Clock (RTC)
The RTC is a module for keeping track of real time, with the following character-
istics:
• Support for external high frequency crystal reference
• Configurable external crystal frequency and frequency division ratio
• Configurable perpetual calendar, configurable items including century, year,
month, day, hour, minute, second and week
• Can count in seconds and query current time
• Supports setting a set of alarms. The configurable items include year, month,
day, hour, minute, and second. When the alarm arrives, the interrupt is trig-
gered.
• Interrupt configurable to support daily, hourly, minute, and second trigger
interrupts
• Readout counter count resolution less than 1 second, the resolution is one
period of the external crystal oscillator
• Data cleared after power-on/reset
3.22 Pulse Width Modulation (PWM)
The PWM module is used to control the duty cycle of an external pulse output.
The user can configure the following functions of the PWM timer module:
• Frequency of pulses, by specifying the PWM timer frequency or period
• PWM timers can be configured to synchronize with other PWM timers or modules
• PWM timers can be in phase with other PWM timers or modules
• Timer count mode: up, down, or up and down in a loop
• Use the prescaler to change the rate of the PWM timer clock (PT_clk). Each
timer has its own prescaler, configured by PWM_TIMERx_PRESCALE in the register
PWM_TIMER0_CFG0_REG. The PWM timer is incremented or decremented at a slower
rate depending on the setting of this register.