Add PWM library to freeRTOS (ble_app_hrs_freertos) example

[Ben]

Hi Sir/Miss,

I use below items to develop:

HW  : PCA10040 (nRF52832)

SDK: 15.2

Softdevice : s132

IDE  : SES V3.40

After I create my task (two same priority tasks to use GPIO to show clock tick), I want to add PWM library to freeRTOS.

I add nrf_drv_ppi.c, nrfx_ppi.c, nrfx_timer.c and app_pwm.c file to project and enable APP_PWM_ENABLED, TIMER_ENABLED, TIMER0_ENABLED, TIMER1_ENABLED, NRFX_PPI_ENABLED, PPI_ENABLED in sdk_config.h. 

And setup the function like PWM library example code (just change 2 to 1 channel )

static volatile bool ready_flag;            // A flag indicating PWM status.

void pwm_ready_callback(uint32_t pwm_id)    // PWM callback function
{
    ready_flag = true;
}

//  PWM initial
void PWM_Init(void)
{
    //  for PWM initial, include "app_pwm.c", "nrfx_timer.c", "nrf_drv_ppi.c", "nrfx_ppi.c", "nrf_nvic.c", "nrf_soc.c"
    
    ret_code_t err_code;

    //  buzzer PWM initial
    APP_PWM_INSTANCE(PWM1,1);                   // Create the instance "PWM1" using TIMER1.

    app_pwm_config_t pwm1_cfg = APP_PWM_DEFAULT_CONFIG_1CH(250L, buzzer_PWM_pin);

    //  Initialize and enable PWM
    err_code = app_pwm_init(&PWM1, &pwm1_cfg, pwm_ready_callback);
    APP_ERROR_CHECK(err_code);
    app_pwm_enable(&PWM1);
}

And compiler it, SES doesn't display any error.

But, two tasks use GPIO that voltage is not correct. It has a 1.36V offset. 

I check system on terminal. It shows fatal error and system reset, and setup breakpoint to check PWM initial err_code.

Err_code is 0x10001000.

I don't know what's meaning, and how to find error code list?

If I mistake on these step, please correct me.

Thank you.

[Susheel Nuguru]

What kind of output do you get with PWM without using FreeRTOS? I am guessing that you need to configure the GPIO pins as HIGH_DRIVE in NRF_GPIO->PIN_CNF before you initialize the pwm driver.

[Ben]

Hi,

Thank you for your reply.

If it's without freeRTOS that PWM output normally.

Before I add PWM function that original GPIO will not be effected in freeRTOS.

I try to use nrf_gpio_cfg_output and nrf_gpio_pin_write to set PWM pin as high before PWM initial. And, I try to add NRF_P0->PIN_CNF[XX] = (GPIO_PIN_CNF_DRIVE_H0H1 << GPIO_PIN_CNF_DRIVE_Pos) before PWM initial in the other way. But, result is the same.

[Susheel Nuguru]

Sorry for the late reply, I was away travelling.

This is strange. The PWM has its own hardware on nRF52 and FreeRTOS does not interfere in that. Not sure why using FreeRTOS affects the output.

Probably depends on if you are doing something in the callback handler and the logic that depends on the flag in that handler. Can you make a minimalistic project for me to be able to reproduce your issue so that i can see what is the bottleneck here?

[Ben]

Hi, 

I've uploaded it to my google driver. Here is data link.

https://drive.google.com/file/d/1G2a4GhuAwkcp3ntuqV5NjWnSXf3z5Fmg/view?usp=sharing 

After you download it, you can check p0.20 that can see the same with me on nrf52 DK.

Thank you.