Boot problem with G120SoM


I have problems to boot my G120 standalone. Plug in the power supply, my system doesn’t boot. After pushing the Reset button, everything works normal.

Now I found an table at the G120 Manual (Image)

My LDR0 and LDR1 are connected to GND by an pinheader. If a Jumper is set, the Pins are connected to GND, if not, the will float, like the schematic at the FEZ Cobra II.

Should i set a HIGH signal on LDR1 Pin 14 with an pullup-resistence to get into the right boot mode?

Thanks :slight_smile:

Thank you andre,

unfortunetly it does’nt work. :frowning:
I give a high signal on LDR1 but the system just start. After an Reset everything is working fine. By the way. To get faster in the boot mode I connected LDR0 to LDR1. Is this a problem? Probably not, because the table told me that a High Signal on LDR 0 doesn’t care.

The FEZ Cobra also have no HIGH Signal on LDR1. How does it work? Is this a software problem? The new Bootloader and Firmaware are installed.



@ Stefan, can you tell us what your device actually does when it boots ? Probably the best way is to describe what device appears in Device Manager in the different boot scenarios

Thanks Brett,

The Pin 8 LDR0 and Pin 14LDR1 are internal HIGH on G120, so I don’t need to set a own HIGH Signal on this Pins.

I tried some things. I started the Device Manager and switch on the supply. LDR0 and LDR1 are HIGH (3.294V), but the Device Manager don’t show me the GHI NETMF Interface. If I press the Reset button on my device, the G120 will boot and I see GHI NETMF Interface in my Device Manager.

LDR0 and LDR1 set on LOW -> Power On -> Reset, LDR0, LDR1 to HIGH -> Bootloader on COM3 is loading in the Device Manager

So for me every importent state is running. The 3V3 Voltage are okay. I don’t know why I have to use the Reset Button.

Could it be a problem with my circuit?

@ Stefan Kraus - Can you reflash the loader and firmware on the device and see if the issue persists?

@ John - Yes I tried, but this didn’t solve the problem.

Maybe I can make a Hardware Reset at starting the G120
But my question is, which Capacity is on the Reset button at the FEZ Cobra II
This isn’t clear in the schematic. I use a 10n 0603 capacity. What does you use?

Thanks you!

This is a part of my schematic

My problem is solved. Now I’m using a 10uF 0804 capacity at my reset-button. This brings a longer LOW Signal to the Reset-Pin. The boot time is 1-2 second longer, but this is okay and it works fine. Now my system starts automatically.

Thank you guys for your help.

We never needed this in our designs but your power supply had a long raise time.