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Hi, I am using Keil microvision 3 and using the NXP MCU LPC2103 . Now whenever i am writing somthing to the pin connect block P0SEL0 (.30 an .31 the value written is 0x40000000) to select the functionality of EXT INT2 then i am getting external interrupt (that is my code is branching to the ISR of EXT INT2).
But the thing is that i have not connected anything to the external interrupt pin (that is P0.15).
The board i am using is MCB2103.
Please help me in this regard. (any pointer to some example code is highly appreciated).
Thanks in advance kaushik
Is the P0.15 perhaps floating. What happens when you connect a pull-up resistor.
No. It is connected to a FPGA board interrupt line but the FPGA is not powered up at all.
thanks kaushik
You have connected an interrupt line to a separate chip that isn't powered up, and you don't have a pull-up?
First of all - be careful about powering only parts of your solution. The FPGA may get voltages way about it's VCC (since it's VCC is zero if not powered up) and that is outside the specifications. unless the FPGA pins are specifically designaed for such use.
Add a serial resistor between FPGA and ARM, and then a pull-up or pull-down resistor depending on what levels you like to have the signals when the FPGA isn't there and driving them.