It seems that modules HE910G and UL865 are unable to run their bootloader in FullSpeed USB mode, though main program does it well.
How could that be??
This is correct, as reported in the HW User Guide, in USB section “In case of a Firmware upgrade using the USB port, it could be done only using an USB 2.0 HS device”.
In fact in bootmode, functionalities are limited and only USB HS driver is loaded. It is a limitation of the Intel chipset.
The thing is our board has only FS USB PHY, so when the USB power (VBUS) is up and HE910G appears on D+ and D-, the HOST started the enumeration process. Since HE910G doesn’t support FS mode, the process leads to the HOST sending DATA OUT packet and receiving NACK response in an endless loop.
1. Is there any workaround to make HE910G bootloader disconnect and run main firmware??
2. What are the conditions for the bootloader to start main firmware??
the only possible workaround is to supply VUSB after 5s from ON/OFF pulse to turn on the module. In this way you power on the USB when the module is already operative.
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