MSP430F6747IPEU, RTC stop working

David Chen2

Here has RTC stop running on our new product design with MSP430F6747IPEU.

We using MCU's internal RTC as our real-time counter.

Quesion descripton: when using the main battery as power supply for RTC module, the RTC runing very good.

But if remove main battery and using coin battery as power supply for RTC module, the MCU's internal RTC stop runnng. (Coin battery can switch automatically to the power supply pin AUXVCC3 when main power turn off)

what is the solution to solve this issue when main power and coin battery switching? need software setting?

thanks,

david

over 9 years ago

0 Jens-Michael Gross over 9 years ago

Guru 227245 points

I’m not sure I correctly understand your hardware setup. However, the RTC and the XT1 crystal are always running from AUXVCC3. So it is not enough to power AUXVCC3 only when main power fails. It needs to be powered (and current is drawn from it) all the time.

0 Ritesh Naik over 9 years ago

Prodigy 10 points

HI,

You have to enable AUXVCC3 supply by setting AUX3CHCTL.

Example>> AUX3CHCTL = AUXCHKEY | AUXCHC_1 | AUXCHV_1 | AUXCHEN;

Thanks,

Ritesh

0 Sheik M over 9 years ago in reply to Ritesh Naik

Prodigy 110 points

Hi Ritesh,

The register AUX3CHCTL which you have mentioned should be used when we use charger circuit to recharge our battery. But David is using a coin battery for AUXVCC3 for RTC. So do we really need to control this register ?

**Attention** This is a public forum

MSP low-power microcontrollers

MSP low-power microcontroller forum

MSP430F6747IPEU, RTC stop working