MSP430FR6989: External ACLK source stops working. What is happening

tunguskar

Part Number: MSP430FR6989

Tool/software:

Hi,

We are getting devices back which completely stopped working. There is also no possibility to connect to the chip at all. Also resets didn`t work. I have devices which worked again after one night.

Question:

We have attached an external ACLK source.

1: What is happening if this one is stop working?

2: What is the MSP doing in this case?

3: Does the MSP switch automatically to the internal clock source?

4: What happens if the external clock source starts working again? Does the MSP switch back automatically

over 1 year ago

0 Johnson He over 1 year ago

TI__Mastermind 29746 points

Hi Tunguskar,

See those description in User Guide for FR6989:

1: What is happening if this one is stop working?

2: What is the MSP doing in this case?

3: Does the MSP switch automatically to the internal clock source?

[ANS] Will switch ACK source from LFXT to LFMODCLK

4: What happens if the external clock source starts working again? Does the MSP switch back automatically

[ANS] No, you need clear fault flag, then colck will switch back to LFXT due to the SELA, SELM, SELA not be changed int his progress. But it you clear fault flag, then the fault occur again, ACLK will slao switch to LFMODCLK.

Thanks!

Best Regards

Johnson

0 tunguskar over 1 year ago in reply to Johnson He

Intellectual 430 points

Hi Johnson, thanks for the answer.

I also read in the datasheet that the internal low frequency clock consumes additional 25uA of current. Is this really the case?

And how does the clock fault detection work. What has to happen that the msp switches to the internal clock?

0 Johnson He over 1 year ago in reply to tunguskar

TI__Mastermind 29746 points

Hi Tunguskar,

Correct, MODSOC will keep 25uA current consumption:

For fault detection, you can check the flag or set the interrupt here:

Thansk!

Best Regards

Johnson

0 tunguskar over 1 year ago in reply to Johnson He

Intellectual 430 points

Thanks for now, but I really need the functionality when the external LF clock is flagged as "not working". I know the flag (LFXTOFFG) but what leads to setting this error flag despite a POR? We see field devices which switch to internal clock despite perfect surrounding conditions.

0 tunguskar over 1 year ago in reply to tunguskar

Intellectual 430 points

Any news on this?

0 Johnson He over 1 year ago in reply to tunguskar

TI__Mastermind 29746 points

Hi，

The LFXTOFFG will be set after POR, this is the default status:

And you need to clear this bit in your code, like this example:

https://dev.ti.com/tirex/explore/node?node=A__ANyHb0-OTMIFl-x-ARraFQ__msp430ware__IOGqZri__LATEST

Thansk!

Best Regards

Johnson

0 tunguskar over 1 year ago in reply to Johnson He

Intellectual 430 points

I said, that POR is known. But there is also mentioned that there could be fault conditions. What fault conditions could be recognized by this peripheral?

0 Johnson He over 1 year ago in reply to tunguskar

TI__Mastermind 29746 points

Hi,

When the LFXT frequency less than 3.5KHz, this fault will be trigger:

Thanks!

Best Regards

Johnson

**Attention** This is a public forum

MSP low-power microcontrollers

MSP low-power microcontroller forum

MSP430FR6989: External ACLK source stops working. What is happening