Using PWM messes up Sys Clk configuration?

Anonymous · ‎May 20, 2016

Hi all,

We use this to start a PWM ...

//Accessing the internal clock reference

aclk_configure(512000, ACLK1, ACLK_FREQ_24_MHZ); // Configure to 512 kHz

//Start the PWMs

pwm_start(PWM_YELLOW_LED_2, PMU_CLK, 0x3E0, 0x3BF); // Blink at 8 kHz

//Setting the GPIO Pins

gpio_configurePin(LEDS_PORT, GPIO_YELLOW_LED_2, GPIO_OUTPUT_ENABLE, LED_OFF);

... which works fine. But when we are done we do this ...

gpio_configurePin(LEDS_PORT, GPIO_YELLOW_LED_2, GPIO_INPUT_ENABLE | GPIO_PULL_UP, LED_OFF);

//Stop the PWM

pwm_disableChannel(1 << PWM_YELLOW_LED_2);

gpio_configurePin(LEDS_PORT, GPIO_YELLOW_LED_2, GPIO_OUTPUT_ENABLE, LED_OFF);

pwm_setReset(PWM_YELLOW_LED_2, 0);

... and the end result is that the system does not work reliably after that.

Sometimes we can't connect or send commands via BLE, etc.

We suspect that the "aclk_configure" does something that would require a reconfiguration call, but the pwm.h API does not tell us what to do.

Any ideas?

Thanks,

Gil

Anonymous · ‎Jun 09, 2016

jakewtorres

- 1 of the PWM channels is working much better with the PWMx_OUTPUT_ENABLE_Pxx definition.

- I've tried LHL_CLK instead of PMU_CLK and that's much better.

I've found out what was causing the problem. It was switching configuration for those pins from GPIO (for "full" brigthness), then to PWM (for partial brightness based on % duty cycle), then again to GPIO, etc. I've decided to just configure it as PWM the whole time, and use 100% duty cycle if I wanted a "full" brightness, and some partial % duty cycle if I want to save power.

Turning an LED on/off now works like this:

void leds_turn_on_off(UINT8 port, UINT8 gpio, UINT8 on_off, UINT16 pwm_level)

{

if (on_off == LED_OFF)

{

switch (gpio)

{

case GPIO_RED_LED:

// Stop the PWM

pwm_disableChannel(1 << PWM_RED_LED);

// Ensure LED is off when done

gpio_configurePin(LEDS_PORT, GPIO_RED_LED, GPIO_INPUT_ENABLE | GPIO_PULL_UP, LED_OFF);

pwm_setReset(PWM_RED_LED, TRUE);

break;

// ... other LEDs

default:

break;

}

else // LEDs on

{

switch (gpio)

{

case GPIO_RED_LED:

pwm_start(PWM_RED_LED, LHL_CLK, PWM_TOGGLE_COUNT, pwm_level);

// Setting the GPIO Pin

gpio_configurePin(LEDS_PORT, GPIO_RED_LED, ENABLE_PWM_RED, LED_OFF); // Initial state is off

break;

// ... other LEDs

default:

break;

}

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Using PWM messes up Sys Clk configuration?

Using PWM messes up Sys Clk configuration?

Re: Using PWM messes up Sys Clk configuration?