CCS/CC1310: drive 4 pins from PWM

Jack Huang37

Part Number:

Tool/software: Code Composer Studio

Any one know how to drive 4 pins(GPIO1 to GPIO4) from PWM generator, to make 4 pins have the SAME output waveform? The PWM generate 38KHz 50% duty cycle waveform, I want this waveform output to 4 pins at the same time. Thanks.

over 4 years ago

0 Jack Huang37 over 4 years ago

Prodigy 250 points

Jack Huang37 said:

Part Number: CC1310

Tool/software: Code Composer Studio

Any one know how to drive 4 pins from PWM, to make 4 pins have the SAME output waveform? Thanks.

0 IUsedToBeARealPerson (M-W) over 4 years ago in reply to Jack Huang37

TI__Guru 58425 points

Hi Jack,

The best way to do this is to setup 4 PWM instances and run each of them with the same setting (1 / IO). You can then, if needed, synchronize the underlying timers to make sure the align in phase if this is required.

What are you using the timers for, clocking other ICs?

0 Jack Huang37 over 4 years ago in reply to IUsedToBeARealPerson (M-W)

Prodigy 250 points

Hi M-W,

Thanks for your reply.

I use the 38KHz PWM outputs (GPIO1~ GPIO4) to drive 4 FETs (IR_LED_1~IR_LED_8), and then these 4 FETs drive an IR emitter with 2n current steps, by delivery the PWM to different pins, the firmware can adjust the current on LED with 15 steps(e.g. drive both IR_LED_8 and IR_LED_1 will get current step 9).

As the pulse is only about 500uS(20 cycles), and the same output phase is need, can we just setup only one PWM and assign it to the pins that I want(e.g. GPIO1 and GPIO4)?

Regards,

Jack

0 IUsedToBeARealPerson (M-W) over 4 years ago in reply to Jack Huang37

TI__Guru 58425 points

Hi Jack,

You can unfortunately not setup one PWM signal to multiple pins, this is not supported by the internal pin controller. You can however setup multiples of the same PWM signal and then synchronize these to have four output pins with the same phase.

0 Jack Huang37 over 4 years ago in reply to IUsedToBeARealPerson (M-W)

Prodigy 250 points

Hi M-W,

Thanks for the information. How good is the phase alignment after synchronization? Can it be less than 1uS?

Regards,

Jack

0 IUsedToBeARealPerson (M-W) over 4 years ago in reply to Jack Huang37

TI__Guru 58425 points

Hi Jack,

Synchronization in this case means that a common "restart" signal goes out to the timers. Following the reset, they will start counting on the same cycle so the phase should really be the same between the signals.

Because of the holidays, TI E2E™ design support forum responses will be delayed from Dec. 25 through Jan. 2. Thank you for your patience.

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CCS/CC1310: drive 4 pins from PWM