Hi, I have a problem with production Nano module. It programs and works fine on a development board from an Auvidea company, but won’t boot on our carrier board. There are similar topics to this, but my case is different in that there is no output on the console at all.
The carrier board was designed according to the design guide and available schematics. I am attaching the power sequence. SYS_RST signal looks fine (goes high about 40ms after POWER_EN), but that’s it. The module doesn’t wake up, the power LED (GPIO4) doesn’t light up, there is nothing on the HDMI output, and nothing on the UART2 (TX is low all the time). The module’s power consumption is initially zero, then spikes at ~1A when raising POWER_EN, and then it settles at 0,4A half a second later, and doesn’t change any more. Nothing changes if I pull POWER_EN down afterwards.
On the screenshot there is PWR_BTN pulse visible, but I also tried without it, and there is no difference.
The 5V supply is stable (10A capability), and all the required caps are mounted near the module. I have measured the supply stability, and there is only a 60mV dip when the POWER_EN goes high (measured directly at the module edge connector pads).
I desoldered almost everything that is connected to the module, and might interfere, and I am out of ideas.
Can anyone tell what could be the reason the module behaves like that?
Does the module require some specific signals or connected peripherals to boot properly?