topic Re: RT1020 flash operation SDK example Question in i.MX Processors

RT1020 flash operation SDK example Question

Seongyon_Jeong — Tue, 09 Jan 2024 06:21:06 GMT

from flash SDK example,

My question is About flexspi_clock_init.

static inline void flexspi_clock_init()
{
#if defined(XIP_EXTERNAL_FLASH) && (XIP_EXTERNAL_FLASH == 1)
    /* Switch to PLL2 for XIP to avoid hardfault during re-initialize clock. */
    CLOCK_InitSysPfd(kCLOCK_Pfd2, 24); /* Set PLL2 PFD2 clock 396MHZ. */
    CLOCK_SetMux(kCLOCK_FlexspiMux, 0x2); /* Choose PLL2 PFD2 clock as flexspi source clock. */
    CLOCK_SetDiv(kCLOCK_FlexspiDiv, 2); /* flexspi clock 133M. */
#else
   ~~~~
#endif
}

In this function , flexspi clock is 132Mz , isn`t it ? why 133,000,000 ?,

Does not it make wrong action ?

/*******************************************************************************
* Code
******************************************************************************/
flexspi_device_config_t deviceconfig = {
.flexspiRootClk = 133000000,
.flashSize = FLASH_SIZE,
.CSIntervalUnit = kFLEXSPI_CsIntervalUnit1SckCycle,
.CSInterval = 2,

Re: RT1020 flash operation SDK example Question

EdwinHz — Tue, 09 Jan 2024 23:09:27 GMT

Hi @Seongyon_Jeong,

The output from the flexspi_clock_init() should be 133MHz. Are you seeing a 131MHz output from your board? Or how are you determining that your output is different from the intended frequency?

BR,
Edwin.

Re: RT1020 flash operation SDK example Question

Seongyon_Jeong — Wed, 10 Jan 2024 00:13:15 GMT

I didn`t check the frequency [directly - physically] using scope.

Just only, with Software description.,

CLOCK_InitSysPfd(kCLOCK_Pfd2, 24); => PLL2 PFD2 clock 396 Mhz
CLOCK_SetMux(kCLOCK_FlexspiMux, 0x2); /* Choose PLL2 PFD2 clock as flexspi source clock. */
CLOCK_SetDiv(kCLOCK_FlexspiDiv, 2);
=> Exactly [ PLL2 PFD2 clock 396 Mhz ] / 3 = 132Mhz , why Say 396 / 3 = 133Mhz ???

Re: RT1020 flash operation SDK example Question

EdwinHz — Wed, 10 Jan 2024 20:28:38 GMT

Hi @Seongyon_Jeong,

You are correct. From the software description it does seem to be 132MHz, but after replicating the setup on ConfigTools' Clocks tool, I also got the same 132MHz. I believe 133MHz is one of the standard values supported from flash devices. However, most likely for simplicity the flexspi_clock_init() routine initially sets it to a near acceptable value of 132MHz. That said, I will comment about this internally to chance the comment to the appropriate frequency.

Thanks for reporting this.

BR,
Edwin.

Re: RT1020 flash operation SDK example Question

Seongyon_Jeong — Thu, 11 Jan 2024 00:10:04 GMT

thanks for your explanation.