TM4C129 Crystal Parameters

Hello Atsuki,

The tested crystal are mentioned as part of the Electrical Section of the Data Sheet. Setting up the Crystal requires use of the API SysCtlClockFreqSet which takes care of the Crystal Range (Hi or Lo) selection.

Regards
Amit

AmitThank you for your reply.The crystal I selected was not on a Data sheet.
So then I have to optimaze by myself.
Now uC has not loaded a program yet, and I would like to optimaize in this situation. It means uC can not run.
I would like to know whether an oscillator cuircuit inside of uC can drive crystal by hardware without software.
Atsuki

Hello Atsuki,

There is no register setting for controlling the parameters. It is recommended that the optimal C1, C2 and Rs be provided by the crystal manufacturer (since the crystal selection is not as per the table) based on the characterization results with a TM4C129 at the manufacturer facility

Regards
Amit

Amit,I am requesting the optimization C1, C2, Rs to a crystal manufacturer.
The manufacturer asked to me whether registers settinng has an influence on oscillator circuit of a crystal.
Now I got it, there is no influence.Thank you.Atsuki

Hello Atsuki,

The only register that affects the IO is the SYSCTL register bit MOSC.OSCRNG for crystal frequency >10MHz.

Regards
Amit

Amit,
According to a data sheet, ORCRNG bit specifies the frequency range of operation of the oscillator and default value is 0 Low frequency range (<10MHz).
I use a 25MHz crystal. What happens in situation ORCRNG bit is 0 ? Atsuki

Hello Atsuki,

The OSCRNG is used to change the gain of the IO based on the frequency. Since it is post the physical pad it will not affect the case you have.

Regards
Amit