F29H85x-SDK  1.02.01.00
 
EPWM XCMP mode

Table of Contents

Introduction

(Note - base frequency and duty cycle of all ePWM's are 50 KHz and 50% respectively. Value of TBPRD = 1999)

This example configures ePWM1, ePWM2, ePWM4, ePWM6 and ePWM8 as follows

  • ePWM1A is allocated all XCMP1-8 registers. ePWM1B has no output.
    • New duty cycle = 50%, new frequency = 200 KHz
    • No Shadow registers used
  • ePWM2A is allocated XCMP1-4 and ePWM2B is allocated XCMP5-8 registers.
    • A and B waveforms are complimentary
    • New duty cycle = 50%, new frequency = 100 KHz
    • No Shadow registers used
  • ePWM4 is configured same as ePWM2 with Minimum Deadband.
    • Minimum Deadband of 200 SYSCLK cycles provided (200 * (1/200 MHz) = 1 micro second)
    • This implies dead band of 1 us is visible on output of ePWM4A and ePWM4B after their falling edge
    • New duty cycle = 40%, new frequency = 100 KHz
  • ePWM6A is allocated XCMP1-4 registers.
    • 3 Shadow register sets used with LOADMULTIPLE mode
    • Shadow set 2 repeated 2 times, Shadow set 3 repeated 4 times
    • ISR to update all Shadow registers with new values after they repeat
    • This means Shadow3 is active for 5 periods, Shadow2 is active for 3 periods and Shadow1 is active for 1 period before their new values are visible in output
  • ePWM8A is allocated XCMP1-4 registers.
    • 3 Shadow register sets used with LOADONCE mode
    • Only Shadow set 3 is loaded from every period
    • ISR updates Shadow 3 register with new values every 5 periods

Shadow register updations for ePWM6 and ePWM8:

  • Only XCMP1 and XCMP4 are updated
  • Update values are +/- 20 TBCTR steps depending on direction of updation
  • GPIO24 is toggled every 9 cycles for ePWM6 after cycling through all shadow buffers and loading new values.
  • Similarly GPIO25 is toggled every 5 cycles for ePWM8

External Connections

  • ePWM1A is on GPIO0
  • ePWM2A is on GPIO2 and ePWM2B is on GPIO3
  • ePWM4A is on GPIO6 and ePWM4B is on GPIO7
  • ePWM6A is on GPIO14
  • ePWM8A is on GPIO10
  • Monitor GPIO24 for ePWM6A new Shadow register value loading
  • Monitor GPIO25 for ePWM8A new Shadow register value loading

Steps to Run the Example

  • When using CCS projects to build, import the CCS project for the required combination and build it using the CCS project menu (see CCS Build Project).
  • When using makefiles to build, note the required combination and build using make command (see Makefile based Build)
  • Establish connections as mentioned in External Connections section.
  • Launch a CCS debug session and run the executable, see CCS_LAUNCH_PAGES

See Also

EPWM