RTC initialisation fails

qxc

Hi,

I'm using come RTC code that bases on the example for the Beaglebone black and found that it does not work, function RTCModuleClkConfig() out of platform/beaglebone/rtc.c never returns. Reason can be found in line 183:

while(CM_WKUP_CM_L3_AON_CLKSTCTRL_CLKTRCTRL_SW_WKUP !=
      (HWREG(SOC_CM_WKUP_REGS + CM_WKUP_CM_L3_AON_CLKSTCTRL) &
       CM_WKUP_CM_L3_AON_CLKSTCTRL_CLKTRCTRL));

This condition is never fulfilled and therefore blocks the initialisation. Simply removig this code solved the problem and RTC is working fine now.

So: what is this code for?

over 8 years ago

0 qxc over 8 years ago

Genius 5820 points

So...nobody from TI knows why they have written this strange piece of code?

0 Lalindra Jayatilleke over 8 years ago in reply to qxc

TI__Mastermind 30365 points

qxc,

I tried this example from C:\ti\AM335X_StarterWare_02_00_01_01\build\armv7a\cgt_ccs\am335x\beaglebone\rtc and it seemed return from RTCModuleClkConfig() on a BBB. Which version of Starterware are you on?

Lali

0 qxc over 8 years ago in reply to Lalindra Jayatilleke

Genius 5820 points

I'm using exactly this version with BeagleBone-patch on an recent BeagleBone Black.

To get a bit closer: what is the exact purpose of this while-loop?

0 Lalindra Jayatilleke over 8 years ago in reply to qxc

TI__Mastermind 30365 points

qxc,

As you may have already noticed, it is a while loop waiting on the CLKTRCTRL to complete setting to 0x2 "Start a software forced wake-up transition on the domain".
According to the TRM pg 1232 a 0x2 wakes-up the clock domain; address 0x44E00418 bits 0 & 1.

Lali

0 qxc over 8 years ago in reply to Lalindra Jayatilleke

Genius 5820 points

OK, so assumed there is no wakeup necessary because the domain is already active - what happens with this loop?

0 Lalindra Jayatilleke over 8 years ago in reply to qxc

TI__Mastermind 30365 points

qxc,

In that case, it may not be needed. It depends on how the application is setup.

Lali

0 qxc over 8 years ago in reply to Lalindra Jayatilleke

Genius 5820 points

OK, and what happens in this case? Would the while-loop block or simply go through?

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RTC initialisation fails