Hello, I see in the schematics, that there is a supervisory circuit handle by the APX823-31W5 ( U117 ) chip. By reading the datasheet of this chip, it's written that the WDI signal ( in udoo case it's WDT_TRG ) has to be periodically triggered by a positive or negative transition to avoid the reset of the system ( because the RESET# pin is connected to the IMX_PORB of the imx6 ). I wonder how this is handle in u-boot ? I've seen this function : Code: static iomux_v3_cfg_t const wdog_pads[] = { MX6_PAD_EIM_A24__GPIO_5_4 | MUX_PAD_CTRL(NO_PAD_CTRL), MX6_PAD_EIM_D19__GPIO_3_19, }; static void setup_iomux_wdog(void) { imx_iomux_v3_setup_multiple_pads(wdog_pads, ARRAY_SIZE(wdog_pads)); gpio_direction_output(WDT_TRG, 0); gpio_direction_output(WDT_EN, 1); gpio_direction_input(WDT_TRG); } But i don't understand why WDT_TRG is in input and how u-boot trigger WDT_TRG periodically... Someone can explain me ? Thanks
Hello raphui, I think that's due to that "Leaving WDI unconnected disables the watchdog" (source: the chip datasheet). So when this pin becomes an input it acts as it's unconnected. I hope that to be helpful. Regards, Abdelrahman
