Kinetis MicrocontrollersのトピックRe: K64F RTC Hard fault during initialization

K64F RTC Hard fault during initialization

priyankb — Sat, 16 Dec 2017 11:16:39 GMT

Hi, I am using MK64FN1M0VLL12 processor and working on RTC. But in the first line itself getting a hard fault. I tried to solve it but failed. can anyone help to solve this problem. External 32.768KHz crystal, Battery connected. Open to any suggestion.

This my initialization code. Thank you.

void rtc_init(void)

{

volatile uint32_t i;

SIM->SCGC6 |= SIM_SCGC6_RTC_MASK;

RTC->SR &= ~RTC_SR_TCE_MASK;

RTC->CR &= ~RTC_CR_OSCE_MASK;

RTC->CR |= RTC_CR_OSCE_MASK;

for(i=0;i<0x60000;i++)

{ }

RTC->SR |= RTC_SR_TCE_MASK;

}

Re: K64F RTC Hard fault during initialization

kerryzhou — Mon, 18 Dec 2017 09:26:09 GMT

Hi Priyank Bhatt,

I suggest you try our official SDK RTC code for K64 at first, these code has been test, it works OK.

Please download the KSDK code from this link:

Welcome | MCUXpresso SDK Builder

Download the SDK_2.3_FRDM-K64F, then you can find the RTC project in this folder:

SDK_2.3_FRDM-K64F\boards\frdmk64f\driver_examples\rtc

If you still have problem after you test it, please kindly let me know!

Have a great day,
Kerry

-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

Re: K64F RTC Hard fault during initialization

priyankb — Mon, 18 Dec 2017 11:29:13 GMT

Thank you Kerry Zhou for replying. Downloaded KSDK 2.3 but no luck.

I noticed one thing. Whenever I try to perform any operation (whether it is read or write) on RTC registers hard fault occurs. So basically clock enable using

SIM_SCGC6 |= SIM_SCGC6_RTC_MASK;

doesn't give any error. But as soon as I try to read/write a register hard fault occur be it software reset on RTC_CR ( RTC_CR |= RTC_CR_SWR_MASK; ) or trying to disable time counter in RTC_SR ( RTC_SR &= ~RTC_SR_TCE_MASK; ).

Now I have few doubts on hardware part:

1. Do I have to always keep the battery connected?

2. Do I need to use external capacitors and resistor while using 32.768KHz crystal oscillator?

One more thing, the default values of the registers associated to RTC are not same as described in the reference manual.

Thank you.

Re: K64F RTC Hard fault during initialization

mjbcswitzerland — Mon, 18 Dec 2017 13:58:02 GMT

A problem with a hard fault on attempted access to the RTC, even after its clock is unmasked in SCGC6, is likely to be a missing VBAT voltage; without the dedicated power supply the RTC is not powered and thus accesses hard-fault.

Regards

Mark

Kinetis: http://www.utasker.com/kinetis.html
Kinetis K64:
- http://www.utasker.com/kinetis/FRDM-K64F.html
- http://www.utasker.com/kinetis/TWR-K64F120M.html
- http://www.utasker.com/kinetis/TEENSY_3.5.html
- http://www.utasker.com/kinetis/Hexiwear-K64F.html
RTC and time keeping: http://www.utasker.com/docs/uTasker/uTasker_Time.pdf

Free Open Source solution: https://github.com/uTasker/uTasker-Kinetis
Working project in 15 minutes video: https://youtu.be/K8ScSgpgQ6M

Professional Kinetis support, one-on-one training and complete fast-track project solutions: http://www.utasker.com/support.html

Re: K64F RTC Hard fault during initialization

priyankb — Tue, 19 Dec 2017 09:40:01 GMT

Thank you Mark, you were correct.

VBAT wasn't getting adequate voltage. Changed some hardware, problem solved.

Thank you once again.

Re: K64F RTC Hard fault during initialization

kevinyuthermo — Thu, 31 May 2018 06:47:48 GMT

How to detect VBAT?

We would like to initialize RTC if VBAT is present, otherwise, skip to init RTC to avoid hard fault.

But there isn't a easy way to detect battery is on or missing, any suggestions?

Re: K64F RTC Hard fault during initialization

mjbcswitzerland — Thu, 31 May 2018 18:49:11 GMT

Kevin

You can use an ADC input to measure the voltage.

But, you can also use the hard fault to detect the lack of VBAT too - your hard fault handler however will need to be able to allow the fault to recover when it occurs so that the code can continue and avoid further use of the RTC.
Since recovery from a hard fault made by the CPU is a little fiddly the simplest method is to set up a DMA transfer from or to it and check whether the DMA channel errors or not. If it doesn't error it can be read/written - if it errors it means that the DMA controller experienced a hard fault (this doesn't need to be recovered from and so is simple to use).

Regards

Mark

uTasker developer and supporter (+5'000 hours experience on +60 Kinetis derivatives in +80 product developments)
Kinetis: http://www.utasker.com/kinetis.html

Re: K64F RTC Hard fault during initialization

priyankb — Mon, 11 Jun 2018 07:12:51 GMT

Kevin

Mark suggested a great option.

Another one could be that you connect VDD and battery to Schottky Diode. The output of diode to VBAT. This way even if your battery is down you will get voltage from Vdd. In this way there is never a problem of hard fault.

Detection: You can detect the battery(down) by reading RTC register. It will always start from 0 every time you start the board and battery is down.

Re: K64F RTC Hard fault during initialization

priyankb — Mon, 11 Jun 2018 07:16:30 GMT

Kevin

@Mark suggested a great option.

Detection: You can detect the battery(down) by reading RTC register. It will always start from 0 every time you start the board and battery is down.

If you aren't able to understand I am attaching a picture of the circuit.

Re: K64F RTC Hard fault during initialization

mjbcswitzerland — Wed, 16 Jan 2019 03:16:28 GMT

Here's the link to the verified uTasker solution:

http://www.utasker.com/forum/index.php?topic=2017.0

Regards

Mark