ble_app_hrs_freertos example questions

[samsam]

Sorry for asking, maybe stupid questions, but looking at ble_app_hrs_freertos example in SDK 16.0.0 cant get through:

1.to documentation  ble_conn_params_init_t. first_conn_params_update_delay  and conn_params_update_delay   should be:  (in number of timer ticks)

So I can’t get it how 5000 ms and 30000ms (as per #define statements) become 5000 and 30000 ticks when RTC frequency as per sdk_config.h for this example is 32768 Hz? What I’m missing?

main.c:

#define FIRST_CONN_PARAMS_UPDATE_DELAY      5000           /**< Time from initiating event (connect or start of notification) to first time sd_ble_gap_conn_param_update is called (5 seconds). */

#define NEXT_CONN_PARAMS_UPDATE_DELAY       30000          /**< Time between each call to sd_ble_gap_conn_param_update after the first call (30 seconds). */

 

static void conn_params_init(void){
…

    cp_init.first_conn_params_update_delay = FIRST_CONN_PARAMS_UPDATE_DELAY;

    cp_init.next_conn_params_update_delay  = NEXT_CONN_PARAMS_UPDATE_DELAY;

….

 

sdk_config.h:

// <0=> 32768 Hz

// <1=> 16384 Hz

…

 #define APP_TIMER_CONFIG_RTC_FREQUENCY 0

2. %s specificator for nrf_log_* doesn’t work in ble_app_hrs_freertos

I inserted those couple lines of code just before vTaskStartScheduler:

 

NRF_LOG_INFO("HRS FreeRTOS example started. 2");

 uint8_t bc_buf2[] = {'7','5','3','\0'};

 NRF_LOG_INFO("\n Received BC2: %s \n", bc_buf2); //WTF doesnt print %s

 uint32_t uint2 = 223377;

 NRF_LOG_INFO("\n Received ui32: %d \n", uint2); // %d  is Ok

 

    // Start FreeRTOS scheduler.

    vTaskStartScheduler();

 

And cant get the correct result neither on UART nor RTT transport:

 

Tera term output:

<info> app: HRS FreeRTOS example started. 2

<info> app:

 Received BC2: Ào

<info> app:

 Received ui32: 223377

<info> app: Fast advertising.

 

JLink RTT Viewer output:

00> <info> app: HRS FreeRTOS example started. 2

00>

00> <info> app:

00>  Received BC2: Ào

00>

00> <info> app:

00>  Received ui32: 223377

00> <info> app: Fast advertising.

 

And I tried almost all combination for the type of the buffer or casting it in the NRF_LOG_INFO statement

 

3. In sdk_config.h APP_TIMER_CONFIG_RTC_FREQUENCY 1 (template ) vs 0 (hrs_freertos)  - what is the objectives to use once 0 (32768 Hz) vs  1 (16384 Hz) ?

 

Thanks

[Susheel Nuguru]

First of all, the FreeRTOS is not running on app_timer.c but instead running on app_timer_freertos.c.

Which means that its timings are not dictated by sdk_config.h but instead the define in FreeRTOSConfig.h -> configTICK_RATE_HZ

You are not totally wrong though.

We cannot get the granualarity of 1ms exactly using a 32768 Hz timer. Since configTICK_RATE_HZ = 1024Hz, one tick is equal 1/1024 seconds, which = 0.976ms.

For realtime systems that need that can of granularity you should use portTICK_PERIOD_MS(time_in_ms) as below

#define FIRST_CONN_PARAMS_UPDATE_DELAY      portTICK_PERIOD_MS (5000)           /**< Time from initiating event (connect or start of notification) to first time sd_ble_gap_conn_param_update is called (5 seconds). */

#define NEXT_CONN_PARAMS_UPDATE_DELAY       portTICK_PERIOD_MS (30000)          /**< Time between each call to sd_ble_gap_conn_param_update after the first call (30 seconds). */

 

Even though this is a bit harmless in current conditions, I can see that it could lead to bad results if the user has changed the configTICK_RATE_HZ rate to cause any other tick different than almost 1ms.

Thanks for lettings us know this.

2.

%s specificator for nrf_log_* doesn’t work in ble_app_hrs_freertos

instead of uint8_t define bc_buf2 as char. String literals work with char and not uints

3. 

In sdk_config.h APP_TIMER_CONFIG_RTC_FREQUENCY 1 (template ) vs 0 (hrs_freertos)  - what is the objectives to use once 0 (32768 Hz) vs  1 (16384 Hz) ?

This define should be irrelevant in your use case since with freeRTOS you are not using app_timer.c file where the above mentioned define becomes valid.

Since you should only use app_timer_freertos.c, the value above is not used   

[samsam]

As this thread was not accepting any Replies until now, I already posted a new Question

https://devzone.nordicsemi.com/f/nordic-q-a/55460/ble_app_hrs_freertos-2

which is actually a continuation of this thread. If there is moderator - feel free to merge both if you find it appropriate. Thanks

[Susheel Nuguru]

we can continue the discussion in the other thread.