It is technically feasible. You can configure Low /High Voltage interrupt and make use of the ISR. For details on configuring LVD interrupt please have a look at the application note: http://www.cypress.com/documentation/application-notes/an54460-psocr-3-and-psoc-5lp-interrupts
Can you please look into this example. Please let us know if you have any further questions.
Thanks for the remark, I didnt know there was an interrupt for it.
I finished the project now and used the ADC to measure the Vdd and start or skip the bootloader accordingly. I only need to check at startup (bootloader) and not in my bootloadable.
I finished my bootloader and here is my result, in case someone else also needs this.
Bootloader starts (for 2 seconds) only when Vdd=5V. In normal application supply is 3V3 so bootloader is skipped.
I used 2 pins to select an i2c adress for the bootloader because I have more identical modules on the same pcb.
By using my MiniProg3 I can select the voltage for testing.
See attachment for the finished bootloader project
I used AN60317 (I2C Bootloader) and the Bootloader and Bootloadable components PDF