QN908x Enter ISP Programatically

[joseraffucci]

Is there a way to jump to ISP mode from code?  The user's manual implies that it can only be done by booting with the CHIP_MODE pin pulled low. 

I will not have a switch or access to the PCB.  I want to have a way to flash the device over USB in case I can't use OTAP.

[gerardo_rodriguez]

Hello Jose Raffucci,

Technically speaking, it may be possible to jump to the start address of the ISP bootloader in ROM, but since the ISP bootloader checks for the CHIP_MODE pin, you would need to bypass this verification somehow or jump to the address after the verification. This task will be complicated since the ISP bootloader source code is not available.

Another thing to keep in mind is that the ISP bootloader expects all the peripherals to be in the reset state, so you would need to deinitialize all your peripherals and clock configuration before jumping to the bootloader.

Regards,

Gerardo

[joseraffucci]

This task will be complicated since the ISP bootloader source code is not available.

That's kind of the point of asking, no?  The correct address to jump to would be a very helpful place to start.