RTC question

Log in or register to post comments
Go To Last Post
7 posts / 0 new
Author
Message
user0123
user0123's picture
Level: New Member
Joined: Thu. May 27, 2010
Posts: 5 View posts
#1
Posted by user0123: Wed. Jan 16, 2019 - 01:51 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi,

 

I'm using RTC on Atmega4808 with this settings

 

	RTC.CTRLA = RTC_PRESCALER_DIV1_gc   /* 1 */
	            | 1 << RTC_RTCEN_bp     /* Enable: enabled */
	            | 0 << RTC_RUNSTDBY_bp; /* Run In Standby: disabled */

	RTC.CLKSEL = RTC_CLKSEL_INT1K_gc; /* 32KHz divided by 32 */

	RTC.INTCTRL = 0 << RTC_CMP_bp    /* Compare Match Interrupt enable: disabled */
	              | 1 << RTC_OVF_bp; /* Overflow Interrupt enable: enabled */

 

The OVF ISR will be called in each 1 ms or in each 65.535s? So with this setup PER=0. RTC will increment CNT at first or will check CNT and call ISR?

 

 

 

 

Tags:

AVR Microcontrollers, megaAVR and tinyAVR
Top
Moe123
Moe123's picture
Level: Resident
Joined: Tue. Aug 7, 2018
Posts: 786 View posts
Posted by Moe123: Wed. Jan 16, 2019 - 03:23 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi,

Refer to this as you are just showing the initialization and part of your code, I cant see where to start.

 

This documentation might help you to get through RTC with OVF interrupt.

http://ww1.microchip.com/downloa...

 

some hints:

- you have to make CCP in order to control the CLK, otherwise your settings will net get through, how to do this ? refer to the datasheet CCP part. try to work around, otherwise post a complete code and show what you really want to do, then you might get some help,

 

regards

Top
user0123
user0123's picture
Level: New Member
Joined: Thu. May 27, 2010
Posts: 5 View posts
Posted by user0123: Wed. Jan 16, 2019 - 03:50 PM (Reply to #2)
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi,

 

My question is about the RTC module.

 

What does this module when PER=0 (period)?

 

When RTC gets the clock can do the following (two scenario)

 

1. Increments CNT. When CNT reaches PER it calls the ISR (assume it is enabled) and sets CNT to 0. In this scenario the ISR will be called at each 65536 clock (because PER is a16bit register).

2. CNT == PER? Yes, because CNT=0 at start and PER=0. In this scenario ISR will be called (CNT will set to 0) at each clock

 

What is the correct?

 

 

 

Top
ki0bk
ki0bk's picture
Level: 10k+ Postman
Joined: Mon. Sep 8, 2014
Posts: 10649 View posts
Location: Over the rainbow
Posted by ki0bk: Wed. Jan 16, 2019 - 03:56 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 1

Moe123 wrote:
otherwise post a complete code and show what you really want to do, then you might get some help,

What if the OP does not want to show his complete code?

 

 

FF = PI > S.E.T

 

Top
user0123
user0123's picture
Level: New Member
Joined: Thu. May 27, 2010
Posts: 5 View posts
Posted by user0123: Wed. Jan 16, 2019 - 04:02 PM (Reply to #4)
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

The complete code is too big.

I'm studying the 

 

http://start.atmel.com/#examples...

AVR IOT WG sensor Node.

 

timeout.c file

 

 

 

Top
Moe123
Moe123's picture
Level: Resident
Joined: Tue. Aug 7, 2018
Posts: 786 View posts
Posted by Moe123: Thu. Jan 17, 2019 - 07:06 AM (Reply to #4)
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 1

ki0bk wrote:

Moe123 wrote:

otherwise post a complete code and show what you really want to do, then you might get some help,

 

What if the OP does not want to show his complete code?

 

 

Freaks never ask for complete code, just a small complete program that demos the problem, often performing this request the OP will discover his own answer.

 

PS: nice catch, ;)

Top
GermanFranz
GermanFranz's picture
Level: Hangaround
Joined: Tue. Feb 27, 2018
Posts: 257 View posts
Location: Germany
Posted by GermanFranz: Mon. Jan 28, 2019 - 12:04 AM (Reply to #6)
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Attention: RTC (Interrupts) using internal 32 kHz oscillator must not be initialized too early because then this oscillator maybe not ready yet.

Top