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MSP432P401R: external HFXT bypass mode oscillator voltage can not be recognited

Part Number: MSP432P401R

hi  

i am using  MSP432 with the  supply voltage is 2.2V.

and my external active crystal  output square wave with which the VPP voltage is 1.1v,

From data sheet,we can see the digital IO's threshold voltage is 0.99v with  2.2V supply voltage.

so i want to know the crystal pin threshold voltage is 0.99v too?

  • Hello Kissn,

    Can you please share the schematic section of your design which shows the crystal part number and how it is being interfaced to MSP432?
  • Unlikely, I believe it is an analog circuit. If you look at the datasheet 6.12.21 it shows that the crystal connects directly to the pin, bypassing any logic gates.
  • Hello Kissn,

    Can you please provide the crystal part number so that we can check if it meets the requirements for the HFXT specifications?
  • TG2520SBN_en(1).pdf

    hi Amit Ashara

    the active crystal part number is  TG2520SBN (VC-TCXO),and the datasheet is send to you, hope to hear your response soon.

    than you !

  • hi Amit Ashara,
    is there any result about this issue?

    and i found a strange phenomenon, if i using the code which used for configure the passive crystal to configure the active crystal,

    the HFXTIFG clears,and the frequency is exactly correct.

    here is my code(the crystal is active crystal with which part number i have sent to you).





    /* DriverLib Includes */
    #include <ti/devices/msp432p4xx/driverlib/driverlib.h>

    /* Standard Includes */
    #include <stdint.h>
    #include <stdbool.h>

    int main(void)
    {
    /* Halting the Watchdog */
    MAP_WDT_A_holdTimer();

    //![Simple CS Config]
    /* Configuring pins for peripheral/crystal usage and LED for output */
    MAP_GPIO_setAsPeripheralModuleFunctionOutputPin(GPIO_PORT_PJ,
    GPIO_PIN3 | GPIO_PIN2, GPIO_PRIMARY_MODULE_FUNCTION);
    MAP_GPIO_setAsOutputPin(GPIO_PORT_P1, GPIO_PIN0);

    /* Just in case the user wants to use the getACLK, getMCLK, etc. functions,
    * let's set the clock frequency in the code.
    */
    CS_setExternalClockSourceFrequency(32000,48000000);

    /* Starting HFXT in non-bypass mode without a timeout. Before we start
    * we have to change VCORE to 1 to support the 48MHz frequency */
    MAP_PCM_setCoreVoltageLevel(PCM_VCORE1);
    MAP_FlashCtl_setWaitState(FLASH_BANK0, 2);
    MAP_FlashCtl_setWaitState(FLASH_BANK1, 2);
    CS_startHFXT(false);

    /* Initializing MCLK to HFXT (effectively 48MHz) */
    MAP_CS_initClockSignal(CS_MCLK, CS_HFXTCLK_SELECT, CS_CLOCK_DIVIDER_1);
    //![Simple CS Config]

    /* Configuring SysTick to trigger at 12000000 (MCLK is 48MHz so this will
    * make it toggle every 0.25s) */
    MAP_SysTick_enableModule();
    MAP_SysTick_setPeriod(12000000);
    MAP_Interrupt_enableSleepOnIsrExit();
    MAP_SysTick_enableInterrupt();

    /* Enabling MASTER interrupts */
    MAP_Interrupt_enableMaster();

    while (1)
    {
    MAP_PCM_gotoLPM0();
    }
    }

    void SysTick_Handler(void)
    {
    MAP_GPIO_toggleOutputOnPin(GPIO_PORT_P1, GPIO_PIN0);
    }
  • Hello Kissn

    When providing an external crystal whose output is not in the full scale of the crystal pin, the oscillator must be enabled for the device. On the other hand if you provide a clock source that has a full swing of 0-Vsupply, it should work.
  • i know,is there any way to meet MSP432's  voltage requrement if i use the this crystal?

    and can you give me the reason why i using  passive crystal configuraton works well?

  • Hello Kissn,

    I believe you are stating it the other way around. When you put 'false" as the argument, it configures the oscillator instead of the bypass path.
  • yes i know,so i want know the reason why this configuration works well.  is there any reasonable explain.

    here is the diagram of the crystal circuit, on the other hand,can you tell me the voltage range  that HFXIN/LFXIN pin   can recognize?

  • Hello Kissn.

    With a small input signal the non-bypass path uses the 2 buffers to bring the output of the crystal to the device voltage swing allowing the crystal to work as expected.
  • if i use this method ,did it work well all the time. any risk?
  • Hello Kissn

    I don't see an issue with using it all the time.

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