Hello Mr. A M Bhatt
As far as I know, Higher prority interrupt can tregger lower priority interrupt. I have made one application which is as followed.
When the system will receive data RI will occur and in interrupt 4 I had written a ISR which will receive data on UART unless it receives ‘*’ on UART.
I had connected a fire sensor on EXT0 and when this interrupt will occur, it will start running one motor.
Here if UART is receiving data and it still hs not received ‘*’ and if EXT0 will receive interrupt, it will stop running ISR of interrupt4 and will go to ISR 1. After completting ISR1, it will return to ISR4 and will wait till ‘*’ has been received.
Check with such conditions.
I may be wrong but this is what I had tried and it was working fine.