[FAQ] PROCESSOR-SDK-AM64X: How to create a PWM using a timer

Below steps, example code could be used for AM62x, AM64x devices. Also concepts and code applies for applications running on M4F and R5F cores. Just update Timer PWM pin, Timer Clock selection address and Timer instance as per user's Timer selection.

For this FAQ, we will focus on AM64x  M4F.

Example code: /cfs-file/__key/communityserver-discussions-components-files/791/4478.hello_5F00_world_5F00_am64x_2D00_evm_5F00_m4fss0_2D00_0_5F00_nortos_5F00_ti_2D00_arm_2D00_clang.zip

Pick a timer

For this example, we are going to pick Timer2.

• Timer 2, ball number is B8 which is available on AM64x EVM for testing purpose
  • From datasheet: AM64x Sitara Processors datasheet (Rev. G) (ti.com) we have

• From "Hello World" example.syscfg we can check:

Timer Configuration:

• Follow below steps from TRM (AM64x/AM243x Technical Reference Manual (Rev. H) (ti.com)):

• For this example, we will configure Toggle, overflow, and auto-reload. From TRM we have (AM64x/AM243x Technical Reference Manual (Rev. H) (ti.com)):

• Timing Diagram of PWM with TIMER_TCLR[7]. From TRM (AM64x/AM243x Technical Reference Manual (Rev. H) (ti.com)):

• If choosing another timer, don't forget to update "AddrTranslateP_getLocalAddr()" to match the correct address. Below, TRM snapshot example for Timer 2. TRM: AM64x/AM243x Technical Reference Manual (Rev. H) (ti.com)

• How to change frequency in example code?
  • Use TIMER_ON_PERIOD macro. This macro is nanosec. Example: if you need a 5KHz (0.2 ms) signal with 50% duty cycle, you will need to configure Time ON to 0.1ms or 100us. In other words, TIMER_ON_PERIOD = 100000 
• How to change duty cycle in example code?
  
  • In order to change duty cycle TMAR and SCPWM are used
  • Different duty cycle cases
    • If duty is 50% duty, then overflow method is used.
    • If duty is other than 50%, then overflow and match mode are used.
    • For 0% duty, set the SCPWM bit as low.
    • For 100% duty, set SCPWM bit as high.