EK-TM4C1294XL external clock

Hello Mei,

Regardless of the uC you would need to perform the test as per the required specification for the application (in this case high pressure test). There are a class of TI uC meant for functional safety application (though high pressure I am not sure, but definitely safety critical)

www.ti.com/.../overview.page

For TM4C129x family of devices a single ended clock source can be used to provide external clock. For single ended clock the OSC0 pin is used. More details can be found in the System Control chapter of the data sheet.

Regards
Amit

Hi Amit,

Thank you for replying. I have a further question.

Can I use the PIOSC as the single system clock, but not connect any external clock to the OSC0 and RTCOSC?

Thank you.

Best regards,

Mei

Hello Mei,

Yes, that can be done. However ensure that the OSC0 pin is connected to GND as per System Design Guideline. Te only disadvantage of not having RTCOSC will be PIOSC trim correction, if the PIOSC drifts larger than +/-3% or if the application requires a stable clock source. Besides that USB and Ethernet usage would require external crystal or single ended stable clock as per ppm requirements.

Regards
Amit

Hi  Amit,

That brings me more question.

The manual says the RTCOSC can be used as the system clock source. Is there any disadvantages to use RTCOSC as the single clock source? Can I use external 32.768kHz clock source rather than an oscillator to connect to the xosc0?

Can I use a resonator as clock source for MOSC and RTCOSC?

Thank you very much.

Best regards,

Mei

Hello Mei

Using RTCOSC as the system clock source would mean

1. The System will work with a 32K clock making it extremely slow in processing and rendering most peripheral usage like I2C, UART, useless due to baud rate or external clock requirements.
2. The PLL cannot be used with a 32K clock

Yes, you can use an external 32KHz single ended clock for the Hibernate Module. I am not sure if resonators have been tested

Regards
Amit

Thank you, Amit.

Best regards,
Mei

Hello Amit,

I have a further question about the Hibernation Clock Source. Is there any difference to use an internal and external 32.768kHz oscillator?

Thank you,

Best regards,

Mei

Hello Mei,

Yes. The Internal clock source for Hibernate is not accurate as the 32.768KHz oscillator. The electrical section of the data sheet would reveal that it can vary from 10 to 90KHz.

Regards
Amit

Hello Amit,
I think I got confused about the 32.786 Oscillator on the figure 7-1, 'Hibernation Module Block diagram'. I thought it was an internal oscillator, but it just indicates where the Oscillator should be connected to, isn't it? Thank you. :)
Best regards,

Mei

Hello Mei

That is the external 32K Oscillator at XOSC0 and XOSC1. The Internal oscillator is marked as "Low Frequency Oscillator"

Regards
Amit

Thank you, Amit.
Mei