Welcome in the forum!
specify "flag" as volatile
clear all pending interrupts not only the masked
Do not send back a character within the interrupt handler!!!
What makes you think that your interrupt handler is entered, but not exited??
The LED will change for some µs which you cannot see with the naked eye.
What Cypress kit are you using? -049?
A working solution: Set uart to "Internal interrupt" and in main-loop check PC_SpiUartGetRxBufferSize() for the number of characters received.
Thanks for your reply, Bob!
The command to clear all pending interrupts is: 'RX_isr_ClearPending();'?
I assumed that the interrupt was fired because I put a line to write data to the terminal inside of the CY_ISR(RX_isr).
I'm using the CY8CKIT-049-42xx.
Am I able to receive 6 byte long data using internal interrupt? Thanks