MIMXRT685SVK Intermittently Fails to Boot From Flash

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MIMXRT685SVK Intermittently Fails to Boot From Flash

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elarsonPN
Contributor I

We have a custom PCB with an RT685 where the architecture is closely modeled off the MIMXRT685-EVK. We are booting from flash by correctly configuring the ISP pins. Intermittently we are seeing failures to boot if we toggle power off and then on with a delay of approximately 0.5 seconds. When this happens, the only way to fix it is to power cycle the system. We have access to the MCU reset, but this has no effect.

We do not have the the MCU and Flash resets tied together, so I burned in the OTP register to correspond to the 2_12 GPIO that asserts the flash reset. This makes it possible to recover by pushing the MCU reset button.

Can you provide guidance on how to debug and recommended timing constraints on the flash reset and reads by the MCU?

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elarsonPN
Contributor I

I changed settings in the flash config file that determines timing and this resolved the intermittent boot issue. Does this change have any unforeseen downstream issues? Since I'm running out of flash would this slow down my code execution?

zephyr\modules\hal\nxp\mcux\mcux-sdk\boards\evkmimxrt685\flash_config\flash_config.cI
 
I changed the csHoldTIme and csSetupTime to 13, previously were set to 3.

 

const flexspi_nor_config_t flexspi_config = {
.memConfig = { .tag = FLASH_CONFIG_BLOCK_TAG,
.version = FLASH_CONFIG_BLOCK_VERSION,
.csHoldTime = 3,
.csSetupTime = 3,
.deviceModeCfgEnable = 1, .deviceModeType = kDeviceConfigCmdType_Generic, .waitTimeCfgCommands = 1,

 

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Gavin_Jia
NXP TechSupport
NXP TechSupport

Hi @elarsonPN ,

Thanks for your interest in NXP MIMXRT series!

Increasing the setup time and hold time does improve the stability of how flash works. This is not directly related to your flash space, if a lot of code is XIP it may have a slight effect, but it is basically negligible.

Best regards,
Gavin

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