MSP430FR2155: Using External 5MHz Oscillator On XT1

Gabriel Moskovitch

Part Number: MSP430FR2155
Other Parts Discussed in Thread: MSP430FR2355, LP-MSPM0G3507

Tool/software:

My Current Code to test setting up the oscillator is as follows:

int main(void) {
    WDT_A_hold(WDT_A_BASE);
//Configure MCLOCK OUtput Pin
    GPIO_setAsPeripheralModuleFunctionOutputPin(
                        GPIO_PORT_P3,
                        GPIO_PIN0,
                        GPIO_PRIMARY_MODULE_FUNCTION
                        );
//Configure XIN and XOUT pins
    GPIO_setAsPeripheralModuleFunctionInputPin(
               GPIO_PORT_P2,
               GPIO_PIN7,
               GPIO_SECONDARY_MODULE_FUNCTION
           );
//Turn on bypass mode
    CS_bypassXT1();
//source MCLOCK from XT1
    CS_initClockSignal(CS_MCLK,CS_XT1CLK_SELECT,CS_CLOCK_DIVIDER_1);
//Clear flags after starting oscillator
    CS_clearAllOscFlagsWithTimeout(1000);
    
    while(1){

    }
}

When run this code gets stuck trying to call CS_bypassXT1(). It gets stuck on the following while statement in cs.c:

while (HWREG8(CS_BASE + OFS_CSCTL7) & (XT1OFFG)) {
    //Clear OSC fault flags
    HWREG8(CS_BASE + OFS_CSCTL7) &= ~(XT1OFFG);

    // 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.
    HWREG8(SFR_BASE + OFS_SFRIFG1) &= ~OFIFG;
}

Any help would be appreciated

over 1 year ago

0 Gary Gao over 1 year ago

TI__Mastermind 41950 points

Have you try the register level code? Or could you share the whole project zip file here?

0 Gabriel Moskovitch over 1 year ago in reply to Gary Gao

Prodigy 20 points

Clock Test.zip

I've looked through the register level. It seems to get an oscillator fault flag, but I haven't been able to find a specific explanation as to what could cause that.

0 zero_cool over 1 year ago in reply to Gabriel Moskovitch

Prodigy 105 points

It seems like we are facing a very similar issue with the external clock connected to Xin, which causes the MSP to lock up. Initially, we thought the MSP was locking when clearing the global oscillator fault flag. However, after further investigation, we found that the MSP430FR2355 gets stuck when switching from the internal DCO (800kHz) to the external clock.

The MCU can remain in this state for some time, and we observed that this behavior is temperature-dependent. After a while, the CPU starts working normally with the external clock. The external clock is not interrupted, and it does not appear to be the cause of the problem.

Our post from last week: MSP430FR2355: MCU Lockup, Clock Issue?"

0 Gabriel Moskovitch over 1 year ago in reply to zero_cool

Prodigy 20 points

I think you may be right. By stuck do you mean endlessly looping your line:

while (HWREG8(SFR_BASE + OFS_SFRIFG1) & OFIFG);

I also have not been able to replicate your temperature issues. I temperature cycled it with a less elegant freeze spray and heat gun but it never escaped the loop.

0 zero_cool over 1 year ago in reply to Gabriel Moskovitch

Prodigy 105 points

Yes, we also first noticed the behavior using freeze spray and a heat gun. Then we placed the hardware into a temperature chamber.

We also tried the following: you can enable MCLK output on a pin. In normal operation, you should first see the internal clock at around 800kHz, and then it should switch to the external clock. However, in our case, sometimes the switch happens, and sometimes it doesn’t.

To test if our code gets stuck in the oscillator fault while loop:

    do
    {
        GPIO_setOutputLowOnPin(GPIO_PORT_P4, GPIO_PIN1);
        //Clear XT1 and DCO fault flags
        HWREG8(CS_BASE + OFS_CSCTL7) &= ~(XT1OFFG | DCOFFG);

        // 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.
        HWREG8(SFR_BASE + OFS_SFRIFG1) &= ~OFIFG;
        GPIO_setOutputHighOnPin(GPIO_PORT_P4, GPIO_PIN1);
    } while (HWREG8(SFR_BASE + OFS_SFRIFG1) & OFIFG);              // Test oscillator fault flag

we simply used a GPIO pin and toggled it.

To reroute MCLK to an output pin, you can use the following code:

P2SEL0 |= BIT6;                     // Select P2.6 as MCLK out
P2SEL1 &= ~(BIT6);                  // Select P2.6 as MCLK out
// Output MCLK on P2.6
P2DIR |= BIT6;                      // Configure P2.6 as output direction pin

When observing the signal waveform on the oscilloscope, we see that our code gets stuck at the point where it needs to switch from the internal 800kHz clock to the 24MHz external clock. This issue lasts for a while before resuming normal operation.

at this point:

CSCTL4 = SELMS__XT1CLK | SELA__REFOCLK;

Image from the oscilloscope when the code gets stuck:

MCLK: Output from the MCLK pin. It starts at around 800kHz and then stays high, but it should switch to 24MHz.
Reset signal: High.
P1.4 pin: Toggles when checking for oscillator faults
Xin: 24MHz.

If you apply a little heat to the MCU with a heat gun, or simply allow the device to warm up, it starts working normally from the point where it was stuck

Sometimes the MCU gets stuck, while other times it works correctly after a reset. This is the waveform from the oscilloscope when everything is functioning properly, a we can see a change from 800 kHz to 24 MHz in the MCLK waveform

Definitely, TI experts should step in to review and provide feedback on both your and our actions. In our case, we cannot explain why it happens, why it gets stuck for a while and then starts working again, but does not reset itself. Perhaps the GPIO pin could help you identify the point where it gets stuck, it could be a great tricks in troubleshooting.

0 Gary Gao over 1 year ago in reply to zero_cool

TI__Mastermind 41950 points

Few comments from myside:

1. could you help to capture the in clock signal capture to make sure the quality is good?

2. You can try this code, I have verify it with a 5.333MHz signal input(generate by a LP-MSPM0G3507 that from a timer's PWM output the duty cycle is 57%) with no issue to a MSP430FR2355

Fullscreen 6518.main.c Download

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 *******************************************************************************
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 * for an API functional library-approach to peripheral configuration.
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//******************************************************************************
//  MSP430FR235x Demo - Configure MCLK for 16MHz operation, and XT1 sourcing
//                                     FLLREF and ACLK.
//
//  Description: Configure MCLK for 16MHz. FLL reference clock is XT1. At this
//                    speed, the FRAM requires wait states.
//                    ACLK = XT1 ~32768Hz, SMCLK = MCLK = 16MHz.
//                    Toggle LED to indicate that the program is running.
//
//           MSP430FR2355
//         ---------------
//        |               |
//        |            XIN|--
//     /|\|               |  ~32768Hz
//      | |           XOUT|--
//      --|RST            |
//        |          P1.2 |---> LED
//        |               |
//        |          P1.0 |---> SMCLK = 16MHz
//        |          P1.1 |---> ACLK  = 32768Hz
//
//
//   Darren Lu
//   Texas Instruments Inc.
//   Oct. 2016
//   Built with IAR Embedded Workbench v6.50 & Code Composer Studio v6.2
//******************************************************************************
#include <msp430.h>

int main(void)
{
    WDTCTL = WDTPW | WDTHOLD;                    // Stop watchdog timer

    // Configure one FRAM waitstate as required by the device datasheet for MCLK
    // operation beyond 8MHz _before_ configuring the clock system.
    FRCTL0 = FRCTLPW | NWAITS_1;

    P2SEL1 |= BIT7;                       // P2.6~P2.7: crystal pins

    CSCTL6 |= XTS_1 | XT1BYPASS | XT1HFFREQ_1 | XT1AGCOFF;

    do
    {
        CSCTL7 &= ~(XT1OFFG | DCOFFG);           // Clear XT1 and DCO fault flag
        SFRIFG1 &= ~OFIFG;
    } while (SFRIFG1 & OFIFG);                   // Test oscillator fault flag



    CSCTL4 = SELMS__XT1CLK | SELA__REFOCLK;   // set XT1 (~32768Hz) as ACLK source, ACLK = 32768Hz
                                                 // default DCOCLKDIV as MCLK and SMCLK source

    P1DIR |= BIT0 | BIT1 | BIT2;                 // set ACLK SMCLK and LED pin as output
    P1SEL1 |= BIT0 | BIT1;                       // set ACLK and  SMCLK pin as second function

    PM5CTL0 &= ~LOCKLPM5;                        // Disable the GPIO power-on default high-impedance mode
                                                 // to activate previously configured port settings

    while(1)
    {
        P1OUT ^= BIT2;                           // Toggle P1.2 using exclusive-OR
        __delay_cycles(8000000);                 // Delay for 80000*(1/MCLK)=0.5s
    }
}

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MSP430FR2155: Using External 5MHz Oscillator On XT1