TM4C129ENCPDT: Program question

Dustin Sun

Expert 1040 points

Part Number: TM4C129ENCPDT

Hi Expert :

Regarding the TM4C129EN MCU crystal, will it oscillate before program ? or just oscillate when programing.

over 5 years ago

0 Ralph Jacobi over 5 years ago

TI__Guru*** 128125 points

Hello Dustin,

Do you mean an external crystal attached to OSC0 and OSC1, or the internal 16 MHz Precision Oscillator (PIOSC)?

0 Dustin Sun over 5 years ago in reply to Ralph Jacobi

Expert 1040 points

Hi Jacobi :
yes, please help to check it~
thanks

0 Ralph Jacobi over 5 years ago in reply to Dustin Sun

TI__Guru*** 128125 points

Hello Dustin,

You still haven't clarified which oscillator you are asking about.

0 Dustin Sun over 5 years ago in reply to Ralph Jacobi

Expert 1040 points

Hi Jacobi :
sorry,
My meaning is external crystal attached to OSC0 and OSC1

0 Ralph Jacobi over 5 years ago in reply to Dustin Sun

TI__Guru*** 128125 points

Hello Dustin,

At POR, the PIOSC is the clock being used. For the external oscillator to startup, the NOXTAL bit in the MOSCCTL register needs to be cleared. Depending if it's single-ended vs crystal, PWRDN may also need to be cleared.

See Section 5.3 of the device datasheet for details on this, it talks about the PLL but part of the process is also getting the external crystal running. Datasheet link: www.ti.com/.../tm4c129encpdt.pdf

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TM4C129ENCPDT: Program question