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Hibernate problem of TM4C123GH6PZ

dannel zhang
Prodigy 40 points

hello,

My MCU is TM4C123GH6PZI. My problem about hibernate is as follow:

1. my tool is IAR, frequency of MCU is 12Mhz, it's my own board.

2. code:

SysCtlPeripheralEnable(SYSCTL_PERIPH_HIBERNATE);
HibernateEnableExpClk(SysCtlClockGet());

HibernateRTCEnable();
HibernateRTCSet(0);
HibernateRTCMatchSet(0, 10);
HibernateWakeSet(HIBERNATE_WAKE_RTC);
SysCtlDelay(8000);

HibernateRequest();
while(1){}

3. problem:

When the code run to the "HibernateEnableExpClk(SysCtlClockGet())", it can't run down. it was just after "HWREG(HIB_CTL) |= HIB_CTL_CLK32EN;" th WRC bit is always 0.

i have searched some answers in the forum and i used the VDD3OFF. The VDD3ON bit of HIB_CTL is zero default. Because the VDD3ON bit in the value of HIB_CTL_CLK32EN is zero. So what can i do to solve this problem?

4. schematics:

I used a external 32.768khz crystal.  The HIB_N was connected to a IC to control the power out to the VDD/VDDA as show on the picture2 "VCC3V3". The "+3.3V" was for the VBAT.

I'm looking forward for the reply! Thanks!

Dannel.Zhang

  • 0
    TI__Guru**** 244380 points

    Hello Dannel,

    Why is there a 1M resistor? The System Design Guidelines make's it very clear on the manner in which the crystal needs to be connected.

    Secondly, if the code gets stuck the first time you initialize the device, then it is most likely that the 32K crystal is not starting. You may want to connect a scope and see if it is oscillating or not.

    If on the other hand it goes into Hibernate with VDD3OFF, then your connection of +3.3 and VCC3V3 is correct for VDD3OFF Mode. In this case make sure that the when Hibernate HIB_N signal goes low, the 3.3V is indeed switching off.

    Regards

    Amit

  • 0 in reply to Amit Ashara
    Prodigy 40 points
    the problem is resolved. the 1Mresistor is just the problem. thanks very much! regarding this problem, your answer is the best answer i have see in this forum.