TMS320F28065: How to use external clock?

Hamid Kavian Athar

Part Number: TMS320F28065
Other Parts Discussed in Thread: C2000WARE

Hi forum,

I am going to use external crystal resonator on X1/X2 pin as my clock source. in InitSysCtrl() function I commented IntOsc1Sel() function and added XtalOscSel() function. but I don't know why it doesn't work anymore. could you please tell me what I should do?

thanks in advance

over 2 years ago

+1 Hareesh Janakiraman over 2 years ago

TI__Guru* 95315 points

You need to ensure there is nothing wrong with your crystal oscillator circuit first. Refer to page 73 of www.ti.com/lit/SPRS698. When the XTAL OSC is not disabled, probe the X1 & X2 pins to ensure you see oscillations.

0 Hamid Kavian Athar over 2 years ago in reply to Hareesh Janakiraman

Intellectual 480 points

Thanks for the reply, I am using RH100-20.000-12-1010-EXT-TR crystal. and I also used 12 pF capacitors for CL1 and CL2.

0 Hareesh Janakiraman over 2 years ago in reply to Hamid Kavian Athar

TI__Guru* 95315 points

Did you probe the X1/X2 pins with an oscilloscope? What did you see? You should have seen 20 MHz sinusoidal oscillations. XTAL OSC is on, by default. If not, you need to investigate why. The C2000ware functions are tested functions.

0 Hamid Kavian Athar over 2 years ago in reply to Hareesh Janakiraman

Intellectual 480 points

Yeah, I checked X1/X2 pins, there is no signal. I am sure C2000ware are OK. I know I am doing something wrong. I have only replaced IntOsc1Sel() function by XtalOscSel() in InitSysCtrl function and then when call InitPll(DSP28_PLLCR,DSP28_DIVSEL) function is 9 and DSP28_DIVSEL is 2.

0 Hamid Kavian Athar over 2 years ago in reply to Hareesh Janakiraman

Intellectual 480 points

the voltage On X1/X2 pins it is DC 1.8V.

0 Hareesh Janakiraman over 2 years ago in reply to Hamid Kavian Athar

TI__Guru* 95315 points

You need to investigate the reason why the crystal oscillator is not oscillating. Without access to the hardware, I will not be able to help you there.

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TMS320F28065: How to use external clock?