Using simple hardware timer with event

[witc]

Hi,

For my app (using zephyr and nrf52840) I want to use hardware Timer like that, is there any manual or example how to do that?  

Need able to set period of timer from 1 to about 100 ms.

1) Set Capture/Compare  reg.

2) Set CLK div for the timer.

3) Set callback (IRQ) for timer event.

4) Run the timer.

Thank you. Jan.

[JamesDougherty]

Hello witc - See if this helps https://devzone.nordicsemi.com/f/nordic-q-a/91996/counter-timer-or-rtc-sample-using-nrf52

[witc]

Thank you, 

I am a novice in the Nordic world. I have gone throught NRF Dev academy, but there is still a lot of unknow. E.G. now I am struggling how to use a peripheral like Timer. I want to call IRQ function every 1 seconds with the hardware timer (in datasheet is written it has 5 Timers). How should I do that? I have found example Alarm, but it can not help me much. 

I tried to modify the example Alarm to find out how to use counter API.

1) In the example is Timer defined according to MCU like that: Unfortunatelly my nrf52840 is not in that list - how can I bind it with my mcu?

#if defined(CONFIG_BOARD_ATSAMD20_XPRO)
#define TIMER DT_LABEL(DT_NODELABEL(tc4))
#elif defined(CONFIG_SOC_FAMILY_SAM)
#define TIMER DT_LABEL(DT_NODELABEL(tc0))
#elif defined(CONFIG_COUNTER_MICROCHIP_MCP7940N)
#define TIMER DT_LABEL(DT_NODELABEL(extrtc0))
#elif defined(CONFIG_COUNTER_RTC0)
#define TIMER DT_LABEL(DT_NODELABEL(rtc0))
#elif defined(CONFIG_COUNTER_RTC_STM32)
#define TIMER DT_LABEL(DT_INST(0, st_stm32_rtc))

2) In example is called 

counter_start

 before it has been initialized - why that?

Finally there is some timer settings  and running the channel: 

alarm_cfg.flags = 0;
alarm_cfg.ticks = counter_us_to_ticks(counter_dev, 2000);
alarm_cfg.callback = timerCallback;
alarm_cfg.user_data = &alarm_cfg;

err = counter_set_channel_alarm(counter_dev, 0,	&alarm_cfg);

Thank you fo the clarification. Jan

[witc]

Here it is, http://leteckaposta.cz/683986250 

I really appreciate the help!

[JamesDougherty]

In main.c change this:

/* Timer for LED toogling */
const struct device *counter_dev;
//counter_dev = device_get_binding(TIMER); // <-- Remove this
counter_dev = DEVICE_DT_GET(TIMER);        // <-- Add this
if (counter_dev == NULL) {
	printk("Device not found\n");
	return;
}
counter_start(counter_dev);

[witc]

Great thanks! Now I can blink with my led by using timer 

Perhaps a bit of a shame that compiler did not point me to this line of code.

Now I am going to elaborate more with peripherals...

[JamesDougherty]

That's interesting, VS Code actually showed red squiggly line under it for me and when I hover it gives the same error you were seeing. 

 

Either way, you're more than welcome and I'm glad I was able to help!

[witc]

not sure if I should establish a new thread... But

1) How can I set if the timer/counter will work in periodic or single mode? 

2) When debugging in VS code, is there any options for stoping the timer when I am currently on the breakpoint? (I do not want my timer to be running when I am on the breakpoint).