RTC calendar

RE: RTC calendar

Ivan Gómez — Thu, 07 Aug 2014 11:02:21 GMT

Hi, I'm trying to get a timestamp based in a RTC calendar, but I don't understand very good how to manage the timers, interruptions and all this staff. Is there any example recommended in order to understand it? I purchased the nRF51822 BLUETOOTH SMART BEACON KIT, so I don't have more example than the one included to show de iBeacon behavior, so any help will be very welcome. I tried using strftime to get the timestamp, and I actually get it but the days behave like seconds almost... they pass really fast, so the seconds are like usecs. Regards.

RE: RTC calendar

Håkon Alseth — Mon, 29 Jul 2013 11:50:49 GMT

Hi,

Note; the app_timer is a library that is softdevice-compatible, but it does not store softdevice events. This library will only run the events setup to use the RTC TICK in your application.

The MAX_TIMERS define will set how many instances you can have called through the app_timer library, meaning battery_handler, hrm_handler, or other handlers that you may have in your application.

The OP_QUEUE_SIZE will give you how many of these pending events that you can have queued up at the time. However, this does not mean that you will have many events queued up, as this is application specific. The app_timer library runs in interrupt priority low, on both RTC and software interrupt, so they cannot interrupt each other. If you have other IRQ-sources running on same priority, which consume more time, then you can build up queue-size.

If you have a situation where your queue size is eaten up, you will get a NRF_ERROR_NO_MEM back

RE: RTC calendar

cocoa — Fri, 26 Jul 2013 22:30:14 GMT

Thank you, but I've not so sure to have understood . Supposing that there are ten events that want to start a timer , OP_QUEUES_SIZE = 10, MAZ_TIMER= 1, softdevice will store all events in a queue, but if the events will be 11, the queue will be corrupted ? (Will be raised an exception or an assert?) Again, with a max timer = 10 and a queue = 11, the 12th event will raise a corruption if all 10 timers are working and nobody of them can accept the 12th event ?

RE: RTC calendar

Håkon Alseth — Fri, 26 Jul 2013 07:41:29 GMT

Forgot to mention; The latter define is application specific and based on the timing of all of your running tasks, and if you are using scheduler or not. You will have to run tests and see what number works for your application

-H

RE: RTC calendar

Håkon Alseth — Fri, 26 Jul 2013 07:39:25 GMT

Hi,

First of I have to say that I have no experience with objc (I'm more of a firmware guy), so I cannot comment on that.

Most of the ble_* examples uses app_timer, mostly without scheduler. "ble_app_template" uses the scheduler, and is more or less a empty shell. Look at that project, and how HRM sets it up to see the difference.

The "OP_QUEUE_SIZE" defines how many operations you can have queued. Lets say you have a situation where you get events are are queueing up (starting a one-time timer) then this define says how many you can have queued before corruption will happen.

BR Håkon

RE: RTC calendar

cocoa — Thu, 25 Jul 2013 19:33:25 GMT

Hi Håkon, seizing upon the answer, I would ask you how exactly is , in APP_TIMER_INIT macro, the OP_QUEUES_SIZE parameter. Is a timer operation like a ObjC block passed to a thread ? How can I set the right size for it ? Can you show me an example ? (best if with and without Scheduler)

Thank you.

-cocoa

RE: RTC calendar

Håkon Alseth — Thu, 25 Jul 2013 08:30:20 GMT

Hi Steven,

This can be achieved by using the app_timer library. If you have alook at any of the ble-examples, all of these use the app_timer library. What you need to adjust is this define: #define APP_TIMER_MAX_TIMERS

This define must be equal or greater to the amount of times "app_timer_create" function is called. If this is not done, the library will not allocate the sufficient amount of RAM to run the added timer function. You create like this: app_timer_create(&m_my_timer_id, APP_TIMER_MODE_REPEATED, my_timeout_handler);

my_timeout_handler is your RTC timer function which is called based on the interval that you set when starting this.

You start the timer by running this function: app_timer_start(m_my_timer_id, INTERVAL, NULL);

For storing information to flash, you can use one of these libraries:

ble_flash
nrf_nvmc

Best regards Håkon