RT1020 FlexSPI NOR speed Configuration.

[harikrishnan_ch]

we have a project with Flexspi NOR flash for XIP.

The default Serial NOR configuration block provided by project setup is as shown below.

 const flexspi_nor_config_t qspiflash_config = {
  .memConfig =
  {
   .tag = FLEXSPI_CFG_BLK_TAG,
   .version = FLEXSPI_CFG_BLK_VERSION,
   .readSampleClksrc=kFlexSPIReadSampleClk_LoopbackFromDqsPad,
   .csHoldTime = 3u,
   .csSetupTime = 3u,
   // Enable DDR mode, Wordaddassable, Safe configuration, Differential     clock
   .sflashPadType = kSerialFlash_4Pads,
   .serialClkFreq = kFlexSpiSerialClk_100MHz,
   .sflashA1Size = 8u * 1024u * 1024u,
   .lookupTable =
   {
    // Read LUTs
    FLEXSPI_LUT_SEQ(CMD_SDR, FLEXSPI_1PAD, 0xEB, RADDR_SDR, FLEXSPI_4PAD,    0x18),
    FLEXSPI_LUT_SEQ(DUMMY_SDR, FLEXSPI_4PAD, 0x06, READ_SDR, FLEXSPI_4PAD, 0x04),
   },
 },
 .pageSize = 256u,
 .sectorSize = 4u * 1024u,
 .blockSize = 256u * 1024u,
 .isUniformBlockSize = false,
};

By changing Fexspi clock frequency to following .serialClkFreq = kFlexSpiSerialClk_133MHz

there is no significant change in SPI clock fequency.

Both with 100Mhz and 133 Mhz setting the Flexspi colck frequence is some where around 127 Mhz 

Could any one provide information? 

thanks and regards

Harikrishnan C

[diego_charles · Accepted solution]

Hi @harikrishnan_ch 

Thank you for reaching out! 

Are you measuring after loading the program over a debug session? If yes,  I want to rule out any influence from the debugger and get your help by not using, letting the MCU boot without any intervention from the debugger. Something similar appeared on this thread Flex Spi Serial Clk not running at the requested speed 100MHz after ROM configuration of the CCM

Could you reproduce this using our i.MX RT1020 EVK?

Would be possible for you to test with another frequency? For example  30 MHz or 50 MHz?

All the best, 

Diego