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DRA746: What effect does the system reset have on the device?

John H. Gardner
Guru 52601 points

Part Number: DRA746

Working with the CCS team, we mentioned to the customer the following command to issue a system reset:  GEL_AdvancedReset("System Reset")

We further noted that System Reset is system level warm reset (i.e. not a POR) that should reset all cores on the device (for multi-core devices) and peripherals. It has the same effect of pushing the nRESET pin on the board. In principle, the warm reset resets everything except the debug logic.

However, there is some variance on what exactly a system reset does depending on the device, which is reason for this e2e post. 

As aforementioned "System reset" is equivalent to pushing the nReset pin.

Does it mean that if the customer has bootloader in QSPI (and the default boot option is QSPI), such system reset will result in executing bootloader?  

  • 0
    TI__Mastermind 42515 points
    Hi John,

    I have forwarded your question to an expert for comment.

    Regards,
    Yordan
  • 0
    TI__Mastermind 19320 points
    HI John,
    You are right, warm reset will not reset everything. Warm reset is there to skip some steps that are already done during power up - DPLL lock, e-fuse load, pinmux, etc.
    And as you said, Debug logic needs to be intact, and some peripherals may not need to be reset (they can be reset-isolated) e.g. Ethernet switch.

    Regarding ROM boot, there exist 2 differences important to user:
    - sysboot pins are sampled after POR. After warm resets they are not checked and POR-sampled values are used
    - Removable devices are not scanned for boot image after warm resets. I.e. SD card, UART, and USB are not polled. All other (incl. QSPI) are considered permanent by ROM and boot will be attempted.

    Everything above is how it should be working, however a silicon bug prevents from using warm resets. Please see erratum i862 Reset Should Use PORz.

    Hope this will be of some help.
    Regards,
    Stan