hi…
Can anyone tell me about the input change interrupts in ARM7.
How can i implement them???
The I/O specifics vary by vendor.
The NXP LPC21xx has external interrupt bits that can be level or edge triggered. (Edge triggered aren’t in the early chip versions).
See the user manual for the LPC21xx for instructions on how to use them.
Essentially, you setup an interrupt for the condition you want. In the ISR, you might alter the condition, e,g., interrupt on rising then falling edge, or some such.
Beware level sensitive, ISR needs to change the condition else there can be an interrupt loop if the bit stays in that state.
Yep, there is no standardization here, even within the same vendors lines of chips.
The LPC2xxx usually allow interrupts on P2.10-12. Some chips allow those to be remapped to some other pins. A bit confusing, but basically this series of parts has up to 4 functions on a pin, one is always the GPIO, and then 3 other functions, like UART, SPI, or EINT0-2 which are the interrupts.
The LPC17xx parts allow interrupts on most any of the P0 and P2 port pins in addition to EINT0-2. It also allows combinations of pins.
The LPC11xx and LPC13xx are yet again different, but similar to each other.
You reference is NXPs user manual. At least for the Cortex parts (11,13,17 series) interrupt code is very simple as each device has a seperate vector, so all you need do is point the vector to your code, and clear the interrupt inside your ISR and do whatever else. As Steve says if you use level interrupts and your code re-enables the interrupt while that level is still true, your code will sit there spinning continually trying to respond to that interrupt.
Thanx u for suggestion…but i am using AT91SAM7S256. So,pl tell me that how can i implement input change interrupt???