Hi all,
In one of our products which has been in the field for more than 5 years, we have observed a problem with the microcontroller P87LPC764 behaviour of late. The IR input from an IR receiver is connected to the External interrupt1 of the microcontroller with External interrupt 0 being used for another function. We find that in some of the micros the External interrupt 1 gets disabled on repeated operation with an IR remote at the rate of 200 - 300 ms continuously. The external interrupt 0 is working under this situation and the firmware is in loop with other functions working normally. Once the micro goes to this state, only power off & on enables the micro to recognize the interrupt again. Software restart / interrupt enable does not help in recovery. We have observed that the IR pulses are received at the interrupt pin normally but the micro is not recognising it whereas it is reading Ext int 0.(I have tried to restart the micro by branching to start under this condition, but the interrupt remains disabled until power is cycled to the micro)

This phenomenon has been observed in some devices and we are also seeing that some other ICs never go to this state even after hours of continuous testing with IR remote at this rate. Can anyone please give some clues in this regard? I have not been able to see any errata published in NXP website in this regard.

The fault is traced down to micro as we see a few ICs where the faulty condition never occurs and a few others where the fault occurs. We already have more than 1000 units in the field and so far we have never received any complaint as no one will be operating the remote at this rate. In case this problem arises,it requires the AC power to be cycled through Mains ON / OFF which is not possible at the customer end.
Has anyone faced similar issues with LPC764? Any suggestions?
Thanks in advance
Santhi