Our customer wants to use the KEA128 Eval-Board in Stand-Alone Mode only powered with a USB Power Supply.
Their board and Software is working fine as long as they have the KEA128 board connected via USB to a PC.
As soon as they replace the PC with a USB Power Supply the board does not start anymore.
They tried to use the on-board Power Connector, but this fails as their add-on boards connected with the KEA128 draw more current than the on-board SBC can support.
The question now is: How can they get their board starting, using only USB Power Supply?
It seems that your USB type 5V power supply can not provide enough current. You said that the KEA128 can not start up even if you use external power supply. What voltage of the external power supply is? do you use 9V or 7V DC power supply? what is the current spec of the external DC power supply?
the USB Power Supply is a 5W Supply. That definitely is good enough for their requirements.
The customer is NOT using the connector for the external Power Supply, but they want to use the connector for the USB.
The issue they discovered is that the Debug MCU seems to somehow turn-off the USB power when it cannot talk to a USB device connected – which obviously is the case if one an external USB power supply is connected.
If the Debug mcu K20 finds out that it can not communicate with host MCU, it does not deassert Reset signal, the KEA128 can not start up I think.
Pls use DC power supply and connect it to P1 Jack, close pin2&3 for J13, have a try.