More interrupt pins

I’d like more interrupt pins. Is there a chip that does the opposite of the 74154 - i.e. when one of 16 pins goes low (or high) it gives a 4-bit address of the device that threw the interrupt?

The 74HC147 will do that.. but it's a priority encoder that outputs the highest interrupt, so you will miss interrupts from lower-priority pins. I think there's a CMOS version too: 40147.

Thank you, Daniel - that's just what I was looking for.

Given the possibility of missing lower priority interrupts, maybe it would be better to have the interrupting device throw a latch which in turn throws the interrupt. Then I just poll the latches to find out who triggered the interrupt. But that sounds a little slow, doesn't it? Not much better than simply polling the devices one by one in a loop and not using interrupts at all. Or I could use the 74HC147 together with latches to save any lower-priority interrupts. Or maybe the Arduino isn't the best choice for a multiple interrupt real-time project, namely a MIDI drum trigger/controller.

At any rate, thanks again for your help. Jesse

A follow-up to this: it seems that the ATMega168 is the solution to this. The I/O pins on this chip can be used as external interrupts, giving you a total of 26, without priority encoding. This, together with the increased flash ram, makes the 168 a very useful part. I'm joining the apparently long list of people waiting for the Bluetooth Arduino.

quick updates

the boards are manufactured and ready for shipment we'll test the bootloader a bit more then the manufacturer will start shipping starting from the customers who have pre-ordered


Where does one go to order one? There doesn't seem to be much about it on the regular arduino web site. No specs, no price.

Where does one go to order one? There doesn't seem to be much about it on the regular arduino web site. No specs, no price.

I think this process take a little time... as you can imagine, a group of unpaid developers does not work the same way as a big Corporation!

But, of course, the unpaid developers build a better product!!!

have a look here for a preview

Seems like the Atmega 168 is soldered in place and cannot be removed anymore.

hey Massimo,

the board looks really good. I am wondering: what kind of connector is that for the DC power? Is it something that one can get plugs for in North America?


It is a industrial connector, frequently used by Remember the picture is still a prototype. I suspect that the production run will have the far inferiour consumer connector again. (Ohh how i hate that plug. try to buy one without the original at hand...)