hoverboard-sideboard-hack-GD/docs/GD32F1x0_Firmware_Library_v3.1.0/Examples/TIMER/TIMERs_cascadesynchro

/*!
    \file  readme.txt
    \brief description of the TIMERs cascade synchro demo
*/

/*
    Copyright (C) 2017 GigaDevice

    2014-12-26, V1.0.0, platform GD32F1x0(x=3,5)
    2016-01-15, V2.0.0, platform GD32F1x0(x=3,5,7,9)
    2016-04-30, V3.0.0, firmware update for GD32F1x0(x=3,5,7,9)
    2017-06-19, V3.1.0, firmware update for GD32F1x0(x=3,5,7,9)
*/

  This demo is based on the GD32150R-EVAL/GD32190R-EVAL board, it shows how to
synchronize TIMER peripherals in cascade mode.
  
  In this example three timers are used:
  1/TIMER1 is configured as master timer:
  - PWM mode is used
  - The TIMER1 update event is used as trigger output  

  2/TIMER2 is slave for TIMER1 and master for TIMER0,
  - PWM mode is used
  - The ITR0(TIMER1) is used as input trigger 
  - External clock mode is used,the counter counts on the rising edges of
  the selected trigger.
  - The TIMER2 update event is used as trigger output.

  3/TIMER0 is slave for TIMER2,
  - PWM mode is used
  - The ITR1(TIMER2) is used as input trigger
  - External clock mode is used,the counter counts on the rising edges of
  the selected trigger.
 
  The TIMERxCLK is fixed to 72 MHz, the TIMER1 counter clock is :
108MHz/3600 = 20 KHz.

  The master timer TIMER1 is running at TIMER1 frequency :
  TIMER1 frequency = (TIMER1 counter clock)/ (TIMER1 period + 1) = 5 Hz 
and the duty cycle = TIMER1_CH1CV/(TIMER1_CAR + 1) = 50%

  The TIMER2 is running:
  - At (TIMER1 frequency)/ (TIMER2 period + 1) = 2.5 Hz and a duty cycle
  equal to TIMER2_CH0CV/(TIMER2_CAR + 1) = 50%

  The TIMER0 is running:
  - At (TIMER2 frequency)/ (TIMER0 period + 1) = 1.25 Hz and a duty cycle
  equal to TIMER0_CH0CV/(TIMER0_CAR + 1) = 50%
  
 Connect the three pins to a logic analyzer to monitor the different waveforms:
  - TIMER1_CH1  pin (PB3)
  - TIMER2_CH0  pin (PA6)
  - TIMER0_CH0  pin (PA8)