First i have to say this lenovo is eating my time a lot…
today my friend Jochen and me tested a little bit around to find out where the cut offs for the power of the internal USB port came from. My thoughts are at the input currents for the modem, the step-up controller or the output current from the 3.3V sensor connector.
We also tested with capacitors in the power lines to prevent peaks in the voltage and current lines.
So far we measured that the sensor port has peaks around 550mA when the modem is connected and right after these peaks the modem resets itself and restarts.
So the used current is really important to get a result. This will take some more time to measure where the problem persists at the moment. I will go for this soon.
Even if I did not get it managed I have a „plan b“ to realize the 3G option. At this time I am going much better with the version taking the power from the 3.3V source like I had actually done.
There will be soon a video online with some tests of the internal and OTG ports and the new Huawei E3331 Modem.
stay tuned it will take more than 2 hours to upload…