Crystal selection

subaananthan T

Other Parts Discussed in Thread: TM4C1231D5PM

In TM4c1231d5PM, if i use a 4Mhz or 8Mhz external crystal, what is the maximum system frequency that can be derived? please explain how to calculate it.

In the same controller, i want to use CAN. as CAN in this controller works on system frequency, how much minimum System frequency is required to operate it at 1Mbps?

over 9 years ago

0 Amit Ashara over 9 years ago

TI__Guru**** 244440 points

Hello Subaanathan,

The maximum system frequency from the list of supported crystal (and frequency range) for TM4C123x is 80MHz. You need to pass the correct crystal value to the SysCtlClockSet API.

Regards
Amit

0 subaananthan T over 9 years ago in reply to Amit Ashara

Prodigy 145 points

Hi Amit

Even with 4Mhz is it possible to get 80Mhz system clock with the API?

Thanks and regards

subaananthan

0 Amit Ashara over 9 years ago in reply to subaananthan T

TI__Guru**** 244440 points

Hello Subaananthan

Yes, it is possible to get 80MHz from 4MHz when using the PLL

Regards
Amit

0 subaananthan T over 9 years ago in reply to Amit Ashara

Prodigy 145 points

Hi amit, thanks for the replay.
If we are able to get the maximum system clock with 4Mhz crystal itself, then why 16Mhz crystal is used in Evaluation board (TM4C123gxl)?

0 Amit Ashara over 9 years ago in reply to subaananthan T

TI__Guru**** 244440 points

Hello Subaananthan,

16MHz is more popular than 4MHz and that USB requires 16MHz.

Regards
Amit

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Crystal selection