CC430F5137 XT1 HF mode

From the datasheet the CC430F5137 can only support low frequency watch crystals on XT1.

http://www.ti.com/lit/ds/symlink/cc430f5137.pdf

Tony

HI Tony,

Thank you for your prompt response..I'm glad you reply to my question even if TI employes are not so far....

I agree, the datasheet for the CC430F5137 (slas554E) does not mention the HF mode for the XT1 but Its all over the place in the USER MANUAL (slau259b) of the CC430 family including the CC430F613x, CC430F612x, CC430F513x.

So whats is considered HF mode for the XT1 on CC430F5137.

I agree the user manual (slau259b) is confusing about XT1 HF mode. Based upon the user manual I think the CC430 devices don't support a HF crystal for XT1 since:

1) Figure 3-1. UCS Block Diagram only shows a LF oscillator symbol for XT1:

2) The only mention in section 3.2.4 XT1 Oscillator of  HF mode is feeding in an external clock signal:

XT1 may be used with an external clock signal on the XIN pin in either LF or HF mode by setting XT1BYPASS. When used with an external signal, the external frequency must meet the data sheet parameters for the chosen mode. XT1 is powered down when used in bypass mode.

Even if you don't get an answer from a TI employee on this thread I suggest submitting a document feedback request on slau259b

Hi Chester,

Yes the oscillator block diagram shows the LF symbol. But puzzle me its that I'm also trying their Bypass mode in HF and still does not work. 

According to the user manual, if the bypass mode is used the XT1 is powered down. In that case one should only make sure the square wave clock into the XIN should meets the digital input's specs of the MSP430.

I have tried the latter and many other configuration without success.....;(

David

Can you post your code which attempts to configure XIN for HF bypass mode?

void
UCS_bypassXT1 ( unsigned int baseAddress,
    unsigned char highOrLowFrequency
    )
{
    ASSERT((UCS_XT1_LOW_FREQUENCY == highOrLowFrequency) ||
        (UCS_XT1_HIGH_FREQUENCY == highOrLowFrequency )
        );

    //Enable HF/LF mode
    HWREG(baseAddress + OFS_UCSCTL6) &= ~XTS;
    HWREG(baseAddress + OFS_UCSCTL6) |= highOrLowFrequency;

    //Switch OFF XT1 oscillator and enable BYPASS mode
    HWREG(baseAddress + OFS_UCSCTL6) |= (XT1BYPASS + XT1OFF);

   
    if (UCS_XT1_LOW_FREQUENCY == highOrLowFrequency){
      while (HWREGB(baseAddress + OFS_UCSCTL7) & (XT1LFOFFG)) {
        //Clear OSC flaut Flags fault flags
        HWREGB(baseAddress + OFS_UCSCTL7) &= ~(XT1LFOFFG);
        
        // Clear the global fault flag. In case the XT1 caused the global fault
        // flag to get set this will clear the global error condition. If any
        // error condition persists, global flag will get again.
        HWREGB(SFR_BASEADDRESS + OFS_SFRIFG1) &= ~OFIFG;
      }
    } else   {
        while (HWREGB(baseAddress + OFS_UCSCTL7) & (XT1HFOFFG)) {
          //Clear OSC flaut Flags fault flags
          HWREGB(baseAddress + OFS_UCSCTL7) &= ~(XT1HFOFFG);
          
          //Clear the global fault flag. In case the XT1 caused the global fault
          //flag to get set this will clear the global error condition. If any
          //error condition persists, global flag will get again.
          HWREGB(SFR_BASEADDRESS + OFS_SFRIFG1) &= ~OFIFG;
        }
      }
 
}

Hi team,

Is there an update available for this inquiry?

Regards,

M

Table 54. Port P5 (P5.0 and P5.1) Pin Functions of the CC430F5137 datasheet SLAS554F shows that the P5SEL.0 bit must be set to use P5.0 as XIN bypass mode. Does your code do that?

Since you seem to be using driverlib the following could be used:

GPIO_setAsPeripheralModuleFunctionInputPin (__MSP430_BASEADDRESS_PORT5_R__, GPIO_PORT_P5, GPIO_PIN0); //XIN
 

If you look at "Crystal Oscillator, XT1, Low-Frequency Mode" in the CC430F5137 datasheet, it specifically states that the square wave in bypass mode should be between 10 and 50kHz. To my knowledge it has no support for XT1 HF.

TonyKao said:

If you look at "Crystal Oscillator, XT1, Low-Frequency Mode" in the CC430F5137 datasheet, it specifically states that the square wave in bypass mode should be between 10 and 50kHz. To my knowledge it has no support for XT1 HF.

On the G2 chips, the situation is similar., However, in bypass mode, it accepts the full frequency range on these chips, even though the datasheet shows the very same limitation.
So it is worth a try.

Suggestion: try with 50kHz first, and ensure that it works (code is corect). if it then doesn't work with higher frequencies, then it simply doesn't work. Period.

Oh that's very interesting. I know that for the F2 chips datasheet states LFXT1 inputs can accept up to 16MHz when put in bypass mode, but this is absent on the G2 and the CC430F5 datasheets (however it is present on F5438a). I wonder why that is?

All devices that have a HF mode on XT1 (including the 5438A and many 2x devices) do accept the same HF in bypass mode too. On G2x, this is probably still working, so only HF oscillator has been removed from the 'full' implementation avialable on most F2x devices.

On the CC, as this is a rather individual design, the XT1 part seems to be built from scratch, only supporting the low frequency even in bypass mode.

Hi Dave,

Sorry to hear the bad news. I don't know what your requirements are, but have you considered sourcing the clock from XT2CLK (the RF clock)? It can source ACLK/MCLK/SMCLK directly or divided, or you can use the FLL to tune the DCO to reasonably accurate arbitrary frequencies. Maybe that's a workable alternative to provide a second HF clock?

Tony