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WDT2 reset

Frederic DUBOIS
Prodigy 40 points

Hello,

I'm working with x-loader, u-boot and a linux 2.6 kernel on an Am3517-based evaluation board. My goal is  to enable the second watchdog.

 

All three pieces of software disable the second watchdog. I modified x-loader so that it enables it with sufficient period so that the board has enough time to boot and launch the app. I removed the code that disables WDT2 in u-boot, and I configured he Linux kernel so that the watchdog driver is a module. These modifications lead to desired behavior, that is if I don't do anything, WDT2 triggers and the card reboots.

The problem is that the board is not  correctly reset: normally, it is supposed to boot from an mmc, and falls back to a nand flash if it fails. When the board reboots due to WDT2, the x-loader from the nand (not the mmc) is launched.

Reset management in WDT2 is quite modular and complex. I have troubles to understand when reading the TRM what can be configured. I would like that a WDT2 reset induce an initialisation of the board as complete as possible (or at least, make it warm-reboot from the mmc, not the nand flash).

What is the correct way to do this?

  • 0
    TI__Genius 16690 points

    Hello Frederic,

    There are two types of reset signal in the device. The 1st reset signal is power on reset (POR) and reset the full logic in the device when the device powers up. The 2nd reset signal is warm reset and occurs when the device is in normal operating state. The warm reset is also a global reset, but it does not affect all the modules in the device. Usually, the device does not require a complete reboot on a warm reset. Several reset sources, such as the global software reset and the watchdog reset, are warm resets.

    The booting sequence is determined by sys_boot pins. However it's different in different reset source. This is described in the section "24.2.3 Boot Configuration" of TRM (SPRUGR0A–October 2009–Revised June 2010). Please refer "Table 24-5. Booting Configuration Pins after a Warm Reset" for the boot sequence after a warm reset from WDT2 and make sure sys_boot pins are configured for MMC boot in first order.

  • 0 in reply to kshin
    Prodigy 40 points

    On SOC8200, Sys_boot 2 & 3 are 1, the rest is 0 except sys_boot 5 that can be 0 or 1 depending on a jumper.

    In this setting, the booting sequence indeed changes bet the cold (POR) and warm boot.