app pwm nrf52

[polarstate]

Hi All,

I am attempting to use 6 PWM channels with the app_pwm library on the nRF52 and am only able to successfully get 4 pwm outputs. Upon changing the 6th channel (PWM2 below ch 0) the softdevice would disconnect. I was able to stop the disconnection adding enable and disable calls before the PWM2 app_pwm_channel_duty_set call but this results in the PWM not being set correctly.

Any suggestions on what to do? I'm going to dig into the raw nrf_drv_pwm driver tomorrow to see if I can get that to perform as intended since I only need fixed pwm cycles for now.

All help is appreciated!!!

Please find the code below:

Globals:

APP_PWM_INSTANCE(PWM0,3);                   // Create the instance "PWM0" using TIMER3.
APP_PWM_INSTANCE(PWM1,1);                   // Create the instance "PWM1" using TIMER1.
APP_PWM_INSTANCE(PWM2,4);                   // Create the instance "PWM2" using TIMER4.

Initialization:

nrf_gpio_cfg_output(RED1_PIN);
nrf_gpio_cfg_output(RED2_PIN);
nrf_gpio_cfg_output(RED3_PIN);
nrf_gpio_cfg_output(BLUE1_PIN);
nrf_gpio_cfg_output(BLUE2_PIN);
nrf_gpio_cfg_output(BLUE3_PIN);


nrf_gpio_pin_clear(RED1_PIN);
nrf_gpio_pin_clear(RED2_PIN);
nrf_gpio_pin_clear(RED3_PIN);
nrf_gpio_pin_clear(BLUE1_PIN);
nrf_gpio_pin_clear(BLUE2_PIN);
nrf_gpio_pin_clear(BLUE3_PIN);

/* 2-channel PWM, 200Hz, output on DK LED pins. */
app_pwm_config_t pwm0_cfg = APP_PWM_DEFAULT_CONFIG_2CH(5000L, RED1_PIN, BLUE1_PIN);
app_pwm_config_t pwm1_cfg = APP_PWM_DEFAULT_CONFIG_2CH(5000L, RED2_PIN,  BLUE2_PIN);
app_pwm_config_t pwm2_cfg = APP_PWM_DEFAULT_CONFIG_2CH(5000L, RED3_PIN, BLUE3_PIN);

/* Initialize and enable PWM. */

uint32_t err_code;
err_code = app_pwm_init(&PWM0,&pwm0_cfg,pwm_ready_callback);
APP_ERROR_CHECK(err_code);
app_pwm_enable(&PWM0);
err_code = app_pwm_init(&PWM1,&pwm1_cfg,pwm_ready_callback);
APP_ERROR_CHECK(err_code);
app_pwm_enable(&PWM1);	
err_code = app_pwm_init(&PWM2,&pwm2_cfg,pwm_ready_callback);
APP_ERROR_CHECK(err_code);
app_pwm_enable(&PWM2);

Softdevice events trigger:

void TurnItOff(void)
{
ready_flag = false;
app_pwm_channel_duty_set(&PWM0, 0, OFF_DUTYCYCLE);
while(!ready_flag);
ready_flag = false;
app_pwm_channel_duty_set(&PWM1, 0, OFF_DUTYCYCLE);
while(!ready_flag);
ready_flag = false;
app_pwm_channel_duty_set(&PWM2, 0, OFF_DUTYCYCLE);
while(!ready_flag);
ready_flag = false;
app_pwm_channel_duty_set(&PWM0, 1, OFF_DUTYCYCLE);
while(!ready_flag);
ready_flag = false;
app_pwm_channel_duty_set(&PWM1, 1, OFF_DUTYCYCLE);
while(!ready_flag);
ready_flag = false;
app_pwm_channel_duty_set(&PWM2, 1, OFF_DUTYCYCLE);
while(!ready_flag);
}
void MakeItHot()
{
ready_flag = false;
app_pwm_channel_duty_set(&PWM0, 0, RED_DUTYCYCLE);
while(!ready_flag);
ready_flag = false;
app_pwm_channel_duty_set(&PWM1, 0, RED_DUTYCYCLE);
while(!ready_flag);
ready_flag = false;
app_pwm_channel_duty_set(&PWM2, 0, RED_DUTYCYCLE);
while(!ready_flag);
}

void MakeItBlue(void)
{
ready_flag = false;
app_pwm_channel_duty_set(&PWM0, 1, BLUE_DUTYCYCLE);
while(!ready_flag);
ready_flag = false;
app_pwm_channel_duty_set(&PWM1, 1, BLUE_DUTYCYCLE);
while(!ready_flag);
ready_flag = false;
app_pwm_channel_duty_set(&PWM2, 1, BLUE_DUTYCYCLE);
while(!ready_flag);
}

[Stefan Birnir Sverrisson]

First thoughts: As I see it, you are setting PWM duty cycles in a BLE interrupt handler. You are busy waiting several times for the PWM callback. How long does that take? While you wait, you are blocking all other BLE callbacks. Try to put your code into main context instead, with e.g. using the scheduler. Another experiment could be to disable the CPU while you wait for the ready_flag, like

while(!ready_flag) { power_manage(); }

Are you adding the PWM to any standard SDK example? What SDK version is your code based on? Are you using nRF52832 rev 1?