arch/arm/tiva: Add complementary PWM mode support

[sydeney]

This commit introduces support for complementary PWM mode on the Tiva C-Series microcontrollers. The feature allows configuring specific PWM generators to operate in complementary mode via Kconfig.

Summary

This change adds support for complementary PWM mode on Tiva C-Series microcontrollers in NuttX.

The feature allows configuring individual PWM generators to operate in complementary mode via Kconfig options.
The implementation preserves backward compatibility, ensuring that the default behavior remains unchanged.
The complementary mode can be enabled for each generator separately using:

• CONFIG_TIVA_PWM_COMPLEMENTARY_G0
• CONFIG_TIVA_PWM_COMPLEMENTARY_G1
• CONFIG_TIVA_PWM_COMPLEMENTARY_G2
• CONFIG_TIVA_PWM_COMPLEMENTARY_G3

The changes are contained within:

• arch/arm/src/tiva/common/tiva_pwm.c

Impact

This change:

• Adds new functionality (complementary PWM mode) without breaking existing behavior.
• Introduces Kconfig options for enabling complementary mode on specific PWM generators.
• Improves flexibility in PWM signal generation for Tiva MCUs.
• Does not introduce any API-breaking changes or impact other drivers.

Testing

The implementation was tested on:

• Target Board: TM4C1294 LaunchPad
• Build Environment: Ubuntu 22.04, GCC 11.3.0, arm-none-eabi-gcc

Configuration: Custom defconfig with:

CONFIG_TIVA_PWM=y
CONFIG_TIVA_PWM_COMPLEMENTARY_G2=y

Before change

After change

[nuttxpr]

[Experimental Bot, please feedback here]

Yes, this PR appears to meet the NuttX requirements, although it is missing some key information in the Testing section.

While the summary and impact sections are well-written and address all the necessary points, the testing section needs improvement. Specifically, it lacks "Testing logs before change" and "Testing logs after change." These logs are crucial for demonstrating the actual impact of the changes and verifying the functionality. Simply stating the target and build environment is insufficient. The logs should show the PWM output before and after enabling the complementary mode to prove the change is working as intended. Include relevant output from a logic analyzer or oscilloscope demonstrating the complementary PWM signals.

Provide concrete examples of the tests performed and their corresponding output. For example:

• Before Change: Show PWM output on G2 without complementary mode (standard single-channel PWM).
• After Change: Show PWM output on G2 with complementary mode enabled, demonstrating the expected inverted signal on the complementary output pin.

By adding these testing logs, the PR will fully comply with the NuttX requirements and provide reviewers with the necessary evidence to evaluate the changes effectively.

[michallenc]

Nice contribution! Apart from those two comments, don't you have to setup GPIO for low PWM output as well? It seems the call for high output GPIO is in tiva_pwm_setup, not sure about the low one, I am not familiar with Tiva drivers.

[acassis]

@sydeney nice work! TIVA arch deserves more care, remember the pandemic when all STM32 are gone. It is good to have alternatives!

[sydeney]

@sydeney nice work! TIVA arch deserves more care, remember the pandemic when all STM32 are gone. It is good to have alternatives!

I agree. My goal is to make TIVA arch as complete as possible to power electronics projects.