(1)Make sure that ERI interrupts are not generated due to a reception error.
(2)Check the ICU IEN register, IPR register, IR register, CPU "I" flag, and SCI SCR register.
(3) Make sure that the SCI module stop bit is released.
For products with the write protection function, release the write protection before writing the module stop bit.
(4)Make sure that the SCR.RIE/SCR.RE bit setting procedure is executed as described in the manual.
(5) For products with MPC, it is necessary to set the PMR register of the IO port. For products without MPC, it is necessary to set the ICR register of the IO port. Please check the above register.