Hi Andy Neil

Since I want to extend interrupt sources and only want use one 8051

An interrupt expander, whatever the type, is usually a bad choice (in a '51 environment).

where can you get more interrupts?
* every timer can be made an external interrupt.
* every comparator, with interrupt associated, can be used as a logical interrupt.
* A PCA can give you 5 additional external interrupts.
* and A/D with limit interrupts, can be used as a locical interrupt.

So, whith something like a SILabs F12x you can have about 15 external interrupts.


an example of converting an interrupt to "external":
configure a timer as a counter, load it with ffff and the very first clock on the input pin gives an interrupt.

Erik

Since I want to extend interrupt sources and only want use one 8051

An interrupt expander, whatever the type, is usually a bad choice (in a '51 environment).

where can you get more interrupts?
* every timer can be made an external interrupt.
* every comparator, with interrupt associated, can be used as a logical interrupt.
* A PCA can give you 5 additional external interrupts.
* and A/D with limit interrupts, can be used as a locical interrupt.

So, whith something like a SILabs F12x you can have about 15 external interrupts.


an example of converting an interrupt to "external":
configure a timer as a counter, load it with ffff and the very first clock on the input pin gives an interrupt.

Erik